EMRFD Message Archive 6586
Message Date From Subject 6586 2011-09-08 23:26:05 Ray WWV 10 MHz Receiver
I started out using the NE602 internal oscillator with a 18 MHz crystal. But the receiver had too much background noise. Thinking the noise could be due to using the internal oscillator, I built a single transistor crystal oscillator and used it to drive pin 6 on the NE602. I didn't really notice any noise reduction.
I am actually using an original NE602 (not the A version) that I purchased back in the mid-80s. Could that be the source of the noise?
Using my FRG7 for comparison purposes on the same antenna, the signal is stronger and quieter on the FRG7. Would I be better off to discard the NE602 and just go to a low gain RF amp into a SBL-1?
Ray
AB7HE6587 2011-09-09 03:43:30 ehydra Re: WWV 10 MHz Receiver
How do you come from 10MHz to 6MHz?
What is the noise-floor at 18MHz?
In a AppNote is the circuit to compensate the NE602 feed-thru:
http://ehydra.dyndns.info/NG/emrfd/
- Henry
--
ehydra.dyndns.info
Ray schrieb:
> I just finished breadboarding (Manhattan style) a WWV receiver using an NE602. The NE602 drives a MC1350 that drives a diode detector into a LM386 amp. The NE602 has a toroid resonated to 6 MHz that drives the MC1350. I have a 2-crystal 6.0 MHz filter between the NE602 and the MC1350.
>
> I started out using the NE602 internal oscillator with a 18 MHz crystal. But the receiver had too much background noise. Thinking the noise could be due to using the internal oscillator, I built a single transistor crystal oscillator and used it to drive pin 6 on the NE602. I didn't really notice any noise reduction.
>
> I am actually using an original NE602 (not the A version) that I purchased back in the mid-80s. Could that be the source of the noise?
>
> Using my FRG7 for comparison purposes on the same antenna, the signal is stronger and quieter on the FRG7. Would I be better off to discard the NE602 and just go to a low gain RF amp into a SBL-1?6588 2011-09-09 06:27:39 Ray Re: WWV 10 MHz Receiver 6589 2011-09-09 07:25:52 Leon Re: WWV 10 MHz Receiver 6590 2011-09-09 07:58:06 Tim Re: WWV 10 MHz Receiver
In my experience: AM BCB or SW stations coming in as intermod are often identifiable as voice modulation. If the AM station reduces power at night you might hear a substantial reduction in intermod.
And VHF FM or TV induced intermod are often continuous and don't have any obvious voice modulation.
You might just want a simple single-tuned circuit or double-tuned circuit in in front of the NE602 to clean up out of band intermod.
9MHz SW intermod can be a little tougher to simply filter out. 6MHz vicinity SW broadcasts can also leak into your 6MHz IF.
IF amplifiers can also have parasitic oscillation that shows up as noise. You could try to differentiate by seeing if the noise comes and goes as you remove the antenna. You might want to simply disable the MC1350's AGC for such testing and re-enable it only when your happy with performance without AGC.
The NE602 crystal oscillator is actually pretty decent and simple and probably worthy of emulation :-)
The FRG7 is revered but it's front end is nothing really to write home about. What it has that your NE602 receiver may lack, is filtering in the front end that reduces AM BCB and VHF levels before the mixer. It also has ceramic filters well suited for AM audio - your two crystal setup is not a bad approximation to overall bandwidth but it won't have the shape factor of the FRG7's ceramic filters which are really pretty good.
Many ham rigs ignore the fine points of AM AGC, demodulation and bandwidth requirements. Things the FRG7 did get right. It's not hard to build a good simple AM receiver (they were made by the millions for the past century) but there are some fine points in their design and listenability that simply aren't applicable to CW or SSB communications.
Most NE602 receivers use a double tuned circuit between the antenna and the NE602. 10.7 MHz IF transformers work well and are easily repurposed for 10MHz applications. But others use transformers wound on ir6591 2011-09-09 09:02:30 Paul Daulton Re: WWV 10 MHz Receiver
will eliminate much of the noise, try a 0.005(0.0047)uf to ground
between the diode and the lm386 or a 0.01uf. this will cut off the high
freq hiss.
Paul k5wms
Quoting Ray :
I just finished breadboarding (Manhattan style) a WWV receiver using
an NE602. The NE602 drives a MC1350 that drives a diode detector into a
LM386 amp. The NE602 has a toroid resonated to 6 MHz that drives the
MC1350. I have a 2-crystal 6.0 MHz filter between the NE602 and the
MC1350.
I started out using the NE602 internal oscillator with a 18 MHz
crystal. But the receiver had too much background noise. Thinking the
noise could be due to using the internal oscillator, I built a single
transistor crystal oscillator and used it to drive pin 6 on the NE602.
I didn't really notice any noise reduction.
I am actually using an original NE602 (not the A version) that I
purchased back in the mid-80s. Could that be the source of the noise?
Using my FRG7 for comparison purposes on the same antenna, the signal
is stronger and quieter on the FRG7. Would I be better off to discard
the NE602 and just go to a low gain RF amp into a SBL-1?
Ray
AB7HE
Paul Daulton K5WMS
beacon WMS 185.302 khz qrss30/slow 24/7
Jacksonville,Ar 72076
em34wu
[Non-text portions of this message have been removed]6592 2011-09-09 09:16:58 Ray Re: WWV 10 MHz Receiver 6593 2011-09-09 09:29:45 Fernando Krouwel Re: WWV 10 MHz Receiver
Try the anti hiss circuit (it works and uses only one 10K ohm resistor and one 10nF capacitor in series and connected between pin 8 and the live wire of the speaker terminal) for the LM386 amplifier on the following link:
http://www.zerobeat.net/g3ycc/hiss.htm
Will improve a little.
73�s
Fernando - PY2ETT
[Non-text portions of this message have been removed]6594 2011-09-09 10:40:48 Tim Re: WWV 10 MHz Receiver
In a textbook HF DTC it's remarkably easy for it to have a lot of VHF leakage due to stray inductances. A low pass filter in addition can make a big difference.
With your 16 MHz LO... wondering if the 5x or 7x harmonic of 16 MHz might be mixing with a local TV or FM station to make your noise. LO filtering won't help much for the odd harmonics. Good low pass filtering between antenna and NE602 will help. I'm trying to steer you away from the LO as a source of the noise, it's really hard to make a crystal oscillator be noisy to that extreme, and the NE602 oscillator just works so well in so many applications.
And it isn't even necessarily distortion happening in the NE602. Having a VHF station blow by the NE602 and get into the crystal filter (crystal filters that will likely let through not just 6 MHz but the high harmonics of 6 MHz) and then present itself at the demodulator could be the issue. If you unhook the antenna from the antenna input, and just clip your antenna or a random length of wire onto the input to the crystal filter, does the noise sound the same?
When I've had VHF or FM stations break through into my homebrew stuff it sounds somewhere between buzzy and swishy and fuzzy. Not sure if any of those sound like what you're hearing.
The neat thing about using a LC oscillator instead of a crystal LO in your receiver is that you now have a tuning knob :-). Radios with tuning knobs are so much more fun than receivers without! You can get a little tuning around 16 MHz with the NE602 and a 16MHz crystal, with a small trimmer or even a couple different fixed capacitors in series with the 16MHz crystal. I'm wondering if your noise is not really noise but is due to the passband not being centered exactly right. Your 6 MHz crystal filter if built with "30 pF parallel" microcessor crystals probably probably really has a center frequency closer to 5.998 MHz (the series resonant frequency) and having the filter off-kilter on an AM signal can sound like noise and distorti6595 2011-09-09 10:46:43 Ray Re: WWV 10 MHz Receiver
The noise is not coming from the LM386. It is coming from the RF circuits. With no antenna connected and volume at maximum level the speaker hiss is barely audible. I have a 10k resistor and .01uF cap6596 2011-09-09 10:56:31 Ray Re: WWV 10 MHz Receiver 6597 2011-09-09 11:02:12 bobtbobbo Re: WWV 10 MHz Receiver
Bob, K1AO6598 2011-09-09 13:00:46 Paul Daulton Re: WWV 10 MHz Receiver
atmosperic noise. Your simple rec has a wide bandwidth, there fore it
will pass a wide range of audio frequencies. Cutting down the high freq
response will decrease the noise by a large factor. I observe the same
thing on a couple of DC and superhet receivers I have using the ne602.
With no hifreq bypass there is a high background noise( which
dissapears when I disconnect the antenna). Adding a .005 bypass in the
audio line does away with the annoiance.Fernando has a good solution
also.
Good luck and let us know when you find a solution.
Paul k5wms
Quoting Ray :
Paul and Fernando,
The noise is not coming from the LM386. It is coming from the RF
circuits. With no antenna connected and volume at maximum level the
speaker hiss is barely audible. I have a 10k resistor and .01uF cap6599 2011-09-09 13:14:04 Chris Trask Re: WWV 10 MHz Receiver
> I just finished breadboarding (Manhattan style) a WWV receiver using
> an NE602. The NE602 drives a MC1350 that drives a diode detector into
> a LM386 amp. The NE602 has a toroid resonated to 6 MHz that drives the
> MC1350. I have a 2-crystal 6.0 MHz filter between the NE602 and the
> MC1350.
>
> I started out using the NE602 internal oscillator with a 18 MHz crystal.
> But the receiver had too much background noise. Thinking the noise could
> be due to using the internal oscillator, I built a single transistor
> crystal oscillator and used it to drive pin 6 on the NE602. I didn't
> really notice any noise reduction.
>
receiver? I've been toying with some sketches since this topic started and
thought I'd ask before I go about reinventing the wheel.
Chris Trask
N7ZWY / WDX3HLB
Senior Member IEEE
http://www.home.earthlink.net/~christrask/6600 2011-09-09 13:57:53 Graham / KE9H Re: WWV 10 MHz Receiver 6601 2011-09-09 14:02:33 Ray Re: WWV 10 MHz Receiver
6602 2011-09-09 14:06:21 Ray Re: WWV 10 MHz Receiver 6603 2011-09-09 14:25:29 Chris Trask Re: WWV 10 MHz Receiver
> > Here's a question: Has anyone ever made a direct-conversion
> > WWV receiver? I've been toying with some sketches since this
> > topic started and thought I'd ask before I go about reinventing
> > the wheel.
> >
>
>
> I built a TRF one last week based on the information at the
> QRP.pops.net site that VE7BPO describes. I wasn't completely
> satisfied with it's performance even though it was fairly good.
> That is why I started down the superhet path.
>
the crystal for the LO is a problem. Making a direct conversion homodyne
with an NE604 has other difficulties. I've made quite a few homodyne AM
receivers using those parts, but they are no longer available in DIP form.
Instead, I have an idea for a synchrodyne version that uses the NE602 as
it's core and a simple 10MHz parallel-resonant crystal.
Chris Trask
N7ZWY / WDX3HLB
Senior Member IEEE
http://www.home.earthlink.net/~christrask/6604 2011-09-09 14:39:37 William Carver Re: WWV 10 MHz Receiver
properly demodulate DSB, whether with carrier (AM) or suppressed carrier
("DSB").
Actually, it's not terribly difficult.
When you have signal applied to the NE602 inputs, and oscillator at the
carrier frequency, the two output pins have a DC level with demodulated
audio superimposed on them. Not just audio. The two outputs go all the
way to DC.
You can connect the differential inputs of an op amp directly to the
NE602 output pins, with a feedback resistor from op amp output back to
the NE602/"-" input of the op amp, and an identical resistor from the
NE602/"+" input of the op amp to ground.
The op amp output acts both as an amplifying for demodulated audio and
produces dc proportional to the phase difference between the oscillator
the carrier. Audio and phase detection by virtue of being direct coupled
to the NE602.
A second op amp to integrate and LPF that DC and drives a varicap to
lock the local oscillator to the original carrier.
Without AGC both audio and DC depends upon signal amplitude. So in a
minimalist SWBC receiver I made (several eons ago, without AGC, I had to
manually change the gain to keep it locked up when there was QSB. The
phase locked audio was gorgeous
If you aren't going for absolute minimal complexity and can dedicate the
NE602 to the phase lock function, then the lock function is better if
you can overdrive the phase detector so its DC output depends only upon
phase, doesn't depend upon amplitude. Classical PLL design applies in
this case. The audio portion will be heavily clipped, though, so you
need to duplicate the detector without overdriving to generate audio.
I just used NE602 for first mixer, single J310 for IF amplifier, then
NE602 detector and a couple of low power op amps and an LM386. Ran off
NiCads for weeks at a time. With a MC1350 you have lots more gain and
signal. MC1350 has two outputs so you could use one MC1350 output to
drive a NE602 product detector, the other output to OVERDRIVE a second
NE602 to generate the dc voltage. The locked BFO drives BOTH NE602
detectors.
Great fun, eh?
W7AAZ6605 2011-09-09 14:48:28 Chris Trask Re: WWV 10 MHz Receiver
> You need to phase lock your BFO to the phase of the incoming signal to
> properly demodulate DSB, whether with carrier (AM) or suppressed carrier
> ("DSB").
>
> Actually, it's not terribly difficult.
>
> When you have signal applied to the NE602 inputs, and oscillator at the
> carrier frequency, the two output pins have a DC level with demodulated
> audio superimposed on them. Not just audio. The two outputs go all the
> way to DC.
>
> You can connect the differential inputs of an op amp directly to the
> NE602 output pins, with a feedback resistor from op amp output back to
> the NE602/"-" input of the op amp, and an identical resistor from the
> NE602/"+" input of the op amp to ground.
>
> The op amp output acts both as an amplifying for demodulated audio and
> produces dc proportional to the phase difference between the oscillator
> the carrier. Audio and phase detection by virtue of being direct coupled
> to the NE602.
>
> A second op amp to integrate and LPF that DC and drives a varicap to
> lock the local oscillator to the original carrier.
>
>
That's pretty much what I had in mind, except to use one opamp as a
differential integrator driving the varactor in a VCXO, and a second opamp
as an audio amplifier/LPF. An LM386 will take care of the rest of the
audio, and perhaps a single stage of RF amplification to make the
sensitivity reasonable.
Chris6606 2011-09-09 15:16:36 William Carver Re: WWV 10 MHz Receiver
> differential integrator driving the varactor in a VCXO, and a second opamp
> as an audio amplifier/LPF. An LM386 will take care of the rest of the
> audio, and perhaps a single stage of RF amplification to make the
> sensitivity reasonable.
>
> Chris
tuning voltage doesn't depends only on phase, not signal amplitude so
its a classical PLL.
The flaw in my receiver (which I still have out in the garage) was
having too little gain, no limiting, so the lock function was weaker
than it could have been. But I was shooting for a hand-carried
battery-operated RX and counting every mA.
You can direct-couple a second-order op amp filter (which has the
integration function) directly to the NE602. At the time I used miniDIP
NE602, and miniDIP op amp, so just stuck them in one 16 pin DIP socket
and almost all point-to-point wiring at the socket. A dc balance
circuit, recently posted as a suggestion for cleaning up the noise
problem in a NE602 mixer, is needed as a zero adjustment for the phase
detector.
The audio detector is the same circuit and construction, except its
NE602 input isn't overdriven, and the op amp is a dc coupled amp with a
shunt capacitor on the feedback resistor to roll off the audio response
instead of an integrator. Just a slightly different arrangement of a few
RC components.
With a modified Collins PTO stretched to tune 4.5-6.5 MHz, the classic
dual-365 pF manual preselector and a simple homebrew 1 MHz IF with a
single-xtal filter, it tuned 3.5-7.5 MHz continuously.6607 2011-09-09 15:21:06 ehydra Re: WWV 10 MHz Receiver
uncorrelated samples of SA602 variants. They were between -15mV and
+5mV. They were older devices: Date codes about 10 years back.
I wondered much about such big offsets and where they would come in a
fully on-chip differential symmetrical design? Mask alignment errors?
Meantime I got fresh ones from digikey out of a single package. Would be
interesting if the newer ones will be closer one to another. This is
work for the weekend.
Interestingly this devices have encrypted date codes. I guess to protect
against chinese relabeling work.
You my wonder why this is important for me?! Because I use the SA602 as
a low-frequency multiplier in this specific design.
- Henry
--
ehydra.dyndns.info
Chris Trask schrieb:
> That's pretty much what I had in mind, except to use one opamp as a
> differential integrator driving the varactor in a VCXO, and a second opamp
> as an audio amplifier/LPF. An LM386 will take care of the rest of the
> audio, and perhaps a single stage of RF amplification to make the
> sensitivity reasonable.6608 2011-09-09 15:38:53 William Carver Re: WWV 10 MHz Receiver
> As I said, it's best to have the phase detector overdriven so theShould have typed "so the output tuning voltage depends only on
> output tuning voltage doesn't depends only on phase, not signal
> amplitude so its a classical PLL.
phase..."
W7AAZ6609 2011-09-09 15:46:20 William Carver Re: WWV 10 MHz Receiver
>The intended application of second mixer in cell phones didn't need DC
> BTW: I measured the output differential offset voltage of various
> uncorrelated samples of SA602 variants. They were between -15mV and
> +5mV. They were older devices: Date codes about 10 years back.
>
> I wondered much about such big offsets and where they would come in a
> fully on-chip differential symmetrical design? Mask alignment errors?
stability but you'd expect the Gilbert cell structure to be pretty
good.
DC offset and stability are important if used as a phase detector. The
offset was easily corrected and as I recall it didn't drift much.
I just looked in my junkbox to get a date code. I know I still have some
(at least 25 years old) but didn't spot which plastic drawer had them.
W7AAZ6610 2011-09-09 16:02:10 Tim Re: WWV 10 MHz Receiver
Laser trimmed gilbert cell parts (e.g. MPY634, AD633) have typical output offsets of low mV too (of course the laser trimming is there to optimize a lot of other parameters too - typically done to minimize full scale error.) SA602's are way too cheap to expect them to be laser trimmed.
6611 2011-09-09 16:09:49 ehydra Re: WWV 10 MHz Receiver
the SA602 does not suppress supply noise anymore.
In the end I think it is better to increase the(/my) ADC resolution at
the output of the SA602 stage and remove the offset in software.
But it always depend on what you intend.
- Henry
William Carver schrieb:
> DC offset and stability are important if used as a phase detector. The--
> offset was easily corrected and as I recall it didn't drift much.
ehydra.dyndns.info6612 2011-09-09 16:28:44 kb1gmx Re: WWV 10 MHz Receiver 6613 2011-09-09 17:10:56 Chris Trask Re: WWV 10 MHz Receiver
> You need to phase lock your BFO to the phase of the incoming signal to
> properly demodulate DSB, whether with carrier (AM) or suppressed carrier
> ("DSB").
>
> Actually, it's not terribly difficult.
>
limiter to ensure adequate signal for the PLL, you might as well simplify
things and use the limited signal for the BFO. This is what I have been
doing with the NE/SA604 and NE/SA605 (a 604 with a 602 included) with
repeatable and satisfactory results. But, since the DIP version is no
longer available I need to consider an alternative approach.
Since WWV at 10MHz is a fairly reliable signal in North America, we can
afford to simplify things. For instance, the RF input impedance of the 602
is such that we can get quite a bit of voltage gain in a properly designed
input circuit consisting of nothing more than two capacitors and a variable
inductor (plus a bypass capacitor). And then the 602 itself will have quite
a bit of conversion gain, so there is little need for any RF stage.
The CA3046 was mentioned earlier, and it would be a good choice for an
RF amplifier with AGC capability using the differential pair and one of the
isolated transistors. The other two transistors can be used for audio
amplification and AGC detection.
But, how good would the bare-bones 602 with a dual opamp and an LM386
audio amplifier perform as a fixed frequency WWV receiver?
>Yes, and that's what this is all about. Make it work well with minimal
> Great fun, eh?
>
cost and readily available parts. Too bad they don't teach this approach to
design anymore. Or any form of design for that matter. Where's Victor
Papanek when you really need him?
Chris Trask
N7ZWY / WDX3HLB
Senior Member IEEE
http://www.home.earthlink.net/~christrask/6614 2011-09-09 18:00:26 Ray Re: WWV 10 MHz Receiver 6615 2011-09-09 19:08:46 William Carver Re: WWV 10 MHz Receiver
> limiter to ensure adequate signal for the PLL, you might as well simplify
> things and use the limited signal for the BFO. This is what I have been
> doing with the NE/SA604 and NE/SA605 (a 604 with a 602 included) with
> repeatable and satisfactory results. But, since the DIP version is no
> longer available I need to consider an alternative approach.
CONSTANT so the output voltage only changes when the relative phase of
the two signals changes.
A PLL doesn't need the carrier, it can lock on the (double) sidebands
alone. Even with a carrier, it's cheaper/simpler/better than limiting
IMHO unless you happen to already have a narrow carrier bandpass filter
already.
There are lots of ways to do a fixed frequency receiver, especially one
like WWV that is often quite strong. Depends upon your design background
and your junkbox as much as esoteric design issues. I wasn't trying to
suggest a different topology, he has it running already, just wants to
make it work better, hi.
W7AAZ6616 2011-09-09 19:23:13 William Carver Re: WWV 10 MHz Receiver
instability. But there is a lot of gain there so it's possible it could
be oscillating due to subtle power supply bypassing issues, position of
nearby wires, etc. Anyway happy to hear it's tamed/quieted down.
6 KHz is wide enough for AM. The 10 KHz ceramic filter will probably
sound nicer, though. A lot depends on YOUR ears. Mine prefer wider IF
bandwidths so they can sort things out for themselves.
The Murata center frequency does put your back to the wall as far as Lo
goes. You need 10,455 or 9,545 KHz and have zero wiggle room. But if you
like the resulting receiver with an analog VFO, but can't get it stable
eough. you might consider one of Kees Talin's Si570 kits. It's not much
more expensive than a one-off "special" from a crystal company and you
might love having it on the bench when you're not listening to WWV.
Or....you could make the receiver work on 5, 10 and 15 MHz with the
Si570. Ain't homebrewing great?
W7AAZ6617 2011-09-09 19:42:38 Chris Trask Re: WWV 10 MHz Receiver
> > Quite right in all regards. But if you are going to resort to using a
> > limiter to ensure adequate signal for the PLL, you might as well
> > things and use the limited signal for the BFO. This is what I have beenYes again. A slick method that you don't see much of is injection
> > doing with the NE/SA604 and NE/SA605 (a 604 with a 602 included) with
> > repeatable and satisfactory results. But, since the DIP version is no
> > longer available I need to consider an alternative approach.
>
> The limiter isn't to ensure adequate signal for the PLL, it's to make it
> CONSTANT so the output voltage only changes when the relative phase of
> the two signals changes.
>
> A PLL doesn't need the carrier, it can lock on the (double) sidebands
> alone. Even with a carrier, it's cheaper/simpler/better than limiting
> IMHO unless you happen to already have a narrow carrier bandpass filter
> already.
>
locking, but it requires a fairly high level signal to get a good lock. I
saw this method used in a British vacuum tube receiver where a heptode was
injection locked to the IF signal carrier. It's a neat way to make a
synthesizer with tubes.
One method I was considering was coupling the limiter of an NE/SA604 to
the antenna terminal (or the amplifier stage output) by way of a
series-resonant crystal. That's about as narrow-band as you can get. A
limiter could also be fashioned with some HCMOS inverters, but each stage
requires two diodes, a resistor, and a capacitor (or crystal).
Chris Trask
N7ZWY / WDX3HLB
Senior Member IEEE
http://www.home.earthlink.net/~christrask/6618 2011-09-09 19:55:26 Craig Smith Re: WWV 10 MHz Receiver
I've enjoyed reading about your WWV receiver project. I'm in the beginning stages of building a BCB AM receiver and have found your comments and associated feedback quite useful.
I'm probably doing a single conversion superhet with a high level mixer preceded by a LP filter as a front end. Most likely a 455 KHz IF. The 6 pole Murata ceramic filters with a bandpass suitable for AM are indeed compelling at $4 each from Mouser last time I checked. I've been pretty successful at building HB Xtal filters for CW at various IF frequencies, but things get more difficult with larger bandwidths. So the Murata approach is the plan unless some kind of problem arises.
Please continue to keep us posted on your progress - always much more to learn!
73. Craig AC0DS
>[Non-text portions of this message have been removed]
6619 2011-09-09 20:13:32 Ray Re: WWV 10 MHz Receiver
Homebrewing is great. But I wonder at times if that is why I have a lot less hair than I used to have. :-)
Ray
AB7HE
6620 2011-09-09 20:45:10 William Carver Re: WWV 10 MHz Receiver
indication.
For super freq-standard receivers they eschew xtal/narrowband filters
because they don't have stable time delay v.s. time and temperature. But
at 10 MHz, looking for perhaps 1x10-8 at best, that's probably not an
issue.
If the goal is a lot more than 1x10-8 then probably better to grab a
Thunderbolt or one of the hp GPS-disciplined oscillators and forget HF.
But we're assuming a whole hell of a lot, Chris. We've babbled on
without really knowing what RAY'S goal is.
W7AAZ6621 2011-09-09 21:04:02 Chris Trask Re: WWV 10 MHz Receiver
> But we're assuming a whole hell of a lot, Chris. We've babbled on
> without really knowing what RAY'S goal is.
>
Chris6623 2011-09-10 07:00:38 Tom Re: WWV 10 MHz Receiver 6624 2011-09-10 08:04:36 Gian Re: WWV 10 MHz Receiver
in my 10000 and one projects (one completed...hi) I have, somewhere, a project on paper for a 10MHz AM receiver for WWWV to synchronize my super counter. Stability and noise here I believe are major problems.
My design was set as follows:
1) 10MHz RF xtal filter (2 to 4 xtals)
2) Following the filter, a chain of 3 cascode DGM amplifier with output LC tuned circuit
3) A diode (schottky or old Ge Gold) envelope detector
4) Low noise OPA
No oscillator and mixer.
Why I thought about this solution?
When I was working in UK, in the middle of 60s, I had to test refurbished Direction Finding Receivers from WW II. These were valve receivers that had no LO to tune from MW to SW. They had valve RF amplifiers in cascade and the tuning was done on all the LC tuned circuits. Clean reception was usually performed. The first stage was noisy... it had too much gain ... so I modified it ... the best DF units.... hi
Maybe you can try my solution and if it does not work...I'll pay a coffey (only one for many)
Have a nice weekend and I am near all for 9/11 anniversary
73
Gian
I7SWX6625 2011-09-10 08:48:04 Ray Re: WWV 10 MHz Receiver 6626 2011-09-10 09:59:17 Justin Pinnix Re: WWV 10 MHz Receiver
If you haven't already, please read http://tf.nist.gov/general/pdf/453.pdf .
It lists several methods for frequency calibration against WWV.
73 de aj4mj
6628 2011-09-10 12:18:37 Chris Trask Re: WWV 10 MHz Receiver
> > Nothing exceeds like excess. :{b
> >
> >
>
> I was going to use it to align my frequency counters. I have one that is
> about 5 years old and a Simpson 710 that is about 35 years old. Neither
> one has ever been aligned. They agree with each other to within about
> 100 Hz at 10 MHz. My guess is the Simpson is more accurate since the
> other one is a Chinese made unit. I was going to feed the audio from the
> WWV receiver into my sound card. Then turn my 10 MHz VCTXCO on with a
> short piece of wire on the output. The WWV receiver will hear that and I
> will use Spectran or Spectrum Lab to zero beat the two signals. I will
> be able to get to within 1 or 2 Hz and then use the VCTXCO to calibrate
> my counters.
>
asked about direct-conversion receivers, I had never considered using an
NE602 as a PLL synchrodyne demodulator. If it works, I'll add a buffer to
the NE602 oscillator so as to use it as a reference source, even though it
will be dirty.
My initial interest in a WWV receiver was to use it to listen to the
time hacks.
Chris Trask
N7ZWY / WDX3HLB
Senior Member IEEE
http://www.home.earthlink.net/~christrask/6632 2011-09-10 15:50:07 ehydra Re: WWV 10 MHz Receiver
-11.4mV. This looks as that uptodate parts are not better. They have
encrypted date codes, so I cannot post the manufacturing date. The
mentioned old parts where from 1991 to 1994 (all Signetics logo). So a
'little' older than 10 years :-)
As we know, SA602 + SA612 + NE602 + NE612 + A-versions are all the same
die. The chip was exactly once improved for better high-frequency
operation somewhere in the past after the burned factory.
- Henry
Tim schrieb:
> An output offset of a couple tens of mV in a NE602 is equivalent to--
> an input offset of a mV or so, and a few mV is entirely typical (not
> worse case) of an untrimmed bipolar op amp or a CA3046 differential
> pair's input offset.
>
ehydra.dyndns.info6633 2011-09-10 22:56:38 victor Re: WWV 10 MHz Receiver 6636 2011-09-11 05:45:55 Chris Trask Re: WWV 10 MHz Receiver
> If you are willing to consider injection locking used in
> a very simple WWV receiver consider this:
> http://sites.google.com/site/kennnick/autodynereceiver
> And:
> http://www.vk2zay.net/article/154
>
I can see what my next project is going to be.
Chris Trask
N7ZWY / WDX3HLB
Senior Member IEEE
http://www.home.earthlink.net/~christrask/6639 2011-09-11 14:39:31 Ray Re: WWV 10 MHz Receiver 6640 2011-09-11 16:43:41 Chris Trask Re: WWV 10 MHz Receiver
> >
> > >
> > > If you are willing to consider injection locking used in
> > > a very simple WWV receiver consider this:
> > > http://sites.google.com/site/kennnick/autodynereceiver
> > > And:
> > > http://www.vk2zay.net/article/154
> > >
> >
> > Now THAT is simple, even simpler than what I was considering.
> > I might simplify it further by removing the varactor, etc., replace C6
> > with a trimmer capacitor, and replace C8 with a series-resonant 10MHz
> > crystal. Or replace C6 with a 10MHz parallel-resonant crystal.
> >
> > I can see what my next project is going to be.
> >
>
> Let me know if you build this and what your results are. The antenna I
> am using is in the attic. WWV seems to be strongest between about 4pm
> and 8pm. Since you are in the same location it will be interesting to
> see if the signal is strong enough for it to lock. It may require an RF
> amp with a few dB of gain to get the signal level up.
>
to understand why there are so many parts in the oscillator feedback loop.
It may be that the designer(s) encountered the same problem that I did with
my crystal test test, being that the closed loop gain has to be just barely
above unity. If the closed loop gain is too high, a large RF input signal
might be required to achieve lock.
I'm going to set the idea of injection-locking aside for now and stay
with the NE602 circuit that some of us have been kicking around. I'm a bit
more comfortable with it, and I would like to see how well it performs as a
synchrodyne demodulator. I have some TLC2272 dual opamps that should work
for the loop integrator and audio preamplifier, as well as some MV209
varactors. I don't have any parallel-resonant 10MHz crystals (?!?!?!?!), so
I'm going to use a series-resonant crystal between pin 7 and the oscillator
tank tap, which is often referred to as a series-resonant Colpitts crystal
oscillator.
Chris6643 2011-09-12 12:46:09 Tim Re: WWV 10 MHz Receiver
I've been dinking around with it6644 2011-09-12 14:37:23 Chris Trask Re: WWV 10 MHz Receiver
> As long as we're talking about AM receivers and NE602's: W7AAZ has a neat
> circuit for AM demodulation using the NE602. It uses the NE602 with an
> op-amp as a squarer. EMRFD figure 6.47(D). Maybe this is what you're
> talking at.
>
work best if one of the ports, particularly pin 6 was the recovered carrier.
Still, if the signl level is high enough and the modulation is not fully
100% it will work to a good degree.
>I found that Circuit Specialists, just a few miles away from me,
> I've been dinking around with it on the bench, trying to use this for
> high-speed feed-forward AGC or at least noise blanking. I'm not gonna
> claim complete success there, but it makes a dang good sounding low-level
> (mV) AM detector. I'm not sure I've heard anything else quite so clean.
>
supposedly has 10MHz parallel-resonant crystals. I'll find out tomorrow. I
was surprised that I did not have some already.
Chris Trask
N7ZWY / WDX3HLB
Senior Member IEEE
http://www.home.earthlink.net/~christrask/6645 2011-09-12 14:58:46 William Carver Re: WWV 10 MHz Receiver
>I'll be darned. That's the AM/CW/SSB detector in my little receiver.
> As long as we're talking about AM receivers and NE602's: W7AAZ has a
> neat circuit for AM demodulation using the NE602. It uses the NE602
> with an op-amp as a squarer. EMRFD figure 6.47(D). Maybe this is what
> you're talking at.
Forgot that circuit was even in there. The DC out is used to voltage
tune the PTO a few hundred Hz to phase lock to the carrier if it's AM.
The "2320" was an early lower power op amp, long obsolete, but "low
power" then was 2 mA. There are better, lot lower power amps with the
same pinout, and virtually any of them will work fine.
W7AAZ6646 2011-09-12 15:37:14 William Carver Re: WWV 10 MHz Receiver
The collector resistors inside the NE602 are, to best of my memory,
nominally 1.5K. So with a 220K feedback resistor the AC+DC gain of the
op amp is about 150. And the NE602 has conversion gain.
The rest of the receiver is two coupled tuned circuits with dual 365 pF
capacitor as used for many decades in handbook receivers for 80m/40m
reception. Then NE602 first mixer, some 1.0 MHz tuned circuits and a
1-pole 1 MHz xtal filter for CW, a J310 for a low gain IF amp, then the
detector of 6.47D. There was close to 20 dB gain between the antenna and
this detector. It had sub-microvolt sensitivity and did NOT require
large signals.
The handbook scheme used a 1700 KHz i.f. and with a 5.2-5.7 MHz VFO and
it tuned 80m/40m ham bands only.
Instead I have 1 MHz i.f. The LO is a Collins PTO with its parallel
capacitance reduced to tune 4.5-6.5 MHz and a Jackson Brothers vernier
to produce a very slow tuning rate. With the antenna filter on the low
side of the LO that LO range gave 3.5-5.5 MHz reception and when tuned
on the high side of the LO it tuned 5.5-7.5 MHz. Voila, 3.5-7.5 MHz
without any gaps. But, I must confess, quite a few turns of the tuning
knob to go from 3525 KHz to 7025 KHz!
A simple digital counter dial shows LO freq: you either added or
subtracted 1 MHz to know where you were tuned. That was before character
LCDs, dial was a MOS counter chip driving the segments of an LED. That
circuit has a bug in it, and every once in a while the dial doesn't work
(Gnash gnash).
Due to the local BFO phase locked to the incoming signal (when its AM)
it does not have any problem with 100% modulated signals. In fact it's
superb listening to SWBC stations because there's no audio distortion
even when heavy QSB causes the carrier amplitude to momentarily drop
below the amplitude of the sidbands. This scheme used to be called
"exalted carrier" detection. Most AM receivers DO distort badly in QSB
when the carrier strength dips below the sideband amplitude.
I remember having that radio next to my bed during the first Gulf War,
listening to the BBC reports in the wee hours.
W7AAZ6649 2011-09-13 01:16:15 ha5rxz Re: WWV 10 MHz Receiver
I've had my EMRFD for years, I wonder how I missed this little gem?
Peter HA5RXZ
6664 2011-09-14 17:24:40 Ray Re: WWV 10 MHz Receiver 6665 2011-09-14 18:06:02 Chris Trask Re: WWV 10 MHz Receiver
> > I'm going to set the idea of injection-locking aside for now and
> > with the NE602 circuit that some of us have been kicking around. I'm abit
> > more comfortable with it, and I would like to see how well it performsas a
> > synchrodyne demodulator. I have some TLC2272 dual opamps that shouldwork
> > for the loop integrator and audio preamplifier, as well as some MV209(?!?!?!?!), so
> > varactors. I don't have any parallel-resonant 10MHz crystals
> > I'm going to use a series-resonant crystal between pin 7 and theoscillator
> > tank tap, which is often referred to as a series-resonant Colpittscrystal
> > oscillator.circuit
>
>
>
> I built the autodyne(VK2ZAY) circuit up ugly style on a small piece of
> board material. So far I haven't been able to get the oscillator to run.Not
> sure what the problem is at this point.I just got the NE602 portion of my synchrodyne circuit running. Need to
>
make a couple of adjustments before I move on to the next portion.
This is fun!
Chris Trask
N7ZWY / WDX3HLB
Senior Member IEEE
http://www.home.earthlink.net/~christrask/6668 2011-09-15 16:15:46 Chris Trask Re: WWV 10 MHz Receiver
> >
> > > I'm going to set the idea of injection-locking aside for now and
> > > stay with the NE602 circuit that some of us have been kicking around.
> > > I'm a bit more comfortable with it, and I would like to see how well
> > > it performs as a synchrodyne demodulator. I have some TLC2272 dual
> > > opamps that should work for the loop integrator and audio
> > > preamplifier, as well as some MV209 varactors. I don't have any
> > > parallel-resonant 10MHz crystals (?!?!?!?!), so I'm going to use a
> > > series-resonant crystal between pin 7 and the oscillator tank tap,
> > > which is often referred to as a series-resonant Colpitts crystal
> > > oscillator.
> >
> >
> >
> > I built the autodyne(VK2ZAY) circuit up ugly style on a small piece of
> > circuit board material. So far I haven't been able to get the oscillator
> > to run. Not sure what the problem is at this point.
> >
>
> I just got the NE602 portion of my synchrodyne circuit running. Need
> to make a couple of adjustments before I move on to the next portion.
>
to work, but it required about -20dNm of input signal to get it to lock up.
And the varactor had to be changed to an MV2101 so as to reduce the runing
range, otherwise it would stop oscillating if it got too far away from the
crystal resonant frequency.
I might have the loop integrator too heavily damped. I'll open it up
and see if there's any improvement.
Chris6669 2011-09-15 16:58:14 ehydra Re: WWV 10 MHz Receiver
Some people add a external resistor in parallel to the internal resistor
between pin 7 and GND.
- Henry
--
ehydra.dyndns.info
Chris Trask schrieb:
> Hmmm... A bit disappointing here also. I did get the NE602 synchrodyne
> to work, but it required about -20dNm of input signal to get it to lock up.
> And the varactor had to be changed to an MV2101 so as to reduce the runing
> range, otherwise it would stop oscillating if it got too far away from the
> crystal resonant frequency.6670 2011-09-15 17:30:52 Chris Trask Re: WWV 10 MHz Receiver
> The NE602 is very sensitive to Q and stops of it is not high enough.
> Some people add a external resistor in parallel to the internal resistor
> between pin 7 and GND.
>
varactor to an MV2101. The problem overall was that using it as a
synchrodyne required more input signal to achieve lock than was practical.
It worked reasonably well when in lock, but wasn't sensitive enough to be
practical.
I've set that aside for now, and am now looking at using the NE604 as a
homodyne receiver. I've done this many times in the past, so it's a known
quantity. What's different here is that I'm coupling the IF amplifier
output to the limiter input by way of a series resonant crystal. The IF
amplifier has a gain of 30dB, and I can get additional gain by way of the
input coupling circuitry.
Chris Trask
N7ZWY / WDX3HLB
Senior Member IEEE
http://www.home.earthlink.net/~christrask/6671 2011-09-15 18:30:27 Ray Re: WWV 10 MHz Receiver
I then connected a 10 MHz source at -20 dB and it locked up immediately. So I put a DTC 10 MHz bandpass filter in front of it. I set the MV2109 pot to mid range and peaked the 8-40pF cap for maximum signal out of the RF amplifier that is to drive the frequency counter.
I don't know what the minimum level required is for it to lock up since the output of my 10 MHz source is fixed. I believe it is probably close to -20 dB though. If I connect a one foot wire to the source output and lay it6672 2011-09-15 18:36:45 Chris Trask Re: WWV 10 MHz Receiver
> >
> > The NE602 is very sensitive to Q and stops of it is not high enough.
> > Some people add a external resistor in parallel to the internal resistor
> > between pin 7 and GND.
> >
>
> The Q of the tank and crystal was not a problem after I changed the
> varactor to an MV2101. The problem overall was that using it as a
> synchrodyne required more input signal to achieve lock than was practical.
> It worked reasonably well when in lock, but wasn't sensitive enough to be
> practical.
>
> I've set that aside for now, and am now looking at using the NE604 as
> homodyne receiver. I've done this many times in the past, so it's a knownThat didn't take long. A series-resonant crystal between two 1.5K
> quantity. What's different here is that I'm coupling the IF amplifier
> output to the limiter input by way of a series resonant crystal. The IF
> amplifier has a gain of 30dB, and I can get additional gain by way of the
> input coupling circuitry.
>
impedances does not give very good selectivity, and I was hoping it would be
sufficient to just pass the 10MHz carrier. Instead, the 60dB gain limiter
is clamping on everything 1MHz either side of centre. So much for that
idea.
Chris6673 2011-09-15 18:57:57 William Carver Re: WWV 10 MHz Receiver
> impedances does not give very good selectivity, and I was hoping it would be
> sufficient to just pass the 10MHz carrier. Instead, the 60dB gain limiter
> is clamping on everything 1MHz either side of centre. So much for that
> idea.
parallel capacitance is only 3.0K ohms. You NE604 doesn't have a chance!
So make two autotransformers, resonate them to 10 MHz and put the 10 Mhz
crystla between low-impedance taps so the xtal has a chance. And instead
of a single xtal make a proper ladder filter. There won't be more than a
few dB of loss and the blowby of even a two-xtal filter will be
dramatically reduced.
By the way Chris, do you happen to know of a source of NOS NE604 or
NE605? They are great for HF and were a tiny faction of the price of
Analog Devices GHz devices. They even came with pins so you could use
them without etching a PCB.
W7AAZ6674 2011-09-15 19:14:25 Dave Re: WWV 10 MHz Receiver
Mouser has both the SA605 and the SA604, but not in DIP packages.
They are in the SOIC package(surface mount .05 inch spacing).
Dave - WB6DHW
<http://wb6dhw.com>
6675 2011-09-15 19:41:26 Chris Trask Re: WWV 10 MHz Receiver
> > That didn't take long. A series-resonant crystal between two 1.5K
> > impedances does not give very good selectivity, and I was hoping it
> > sufficient to just pass the 10MHz carrier. Instead, the 60dB gainlimiter
> > is clamping on everything 1MHz either side of centre. So much for thatI've been kicking a few ideas around, and that was one of them. I was
> > idea.
>
> At 1.5K ohms you can't expect much out of a single xtal, 5 pF of
> parallel capacitance is only 3.0K ohms. You NE604 doesn't have a chance!
>
> So make two autotransformers, resonate them to 10 MHz and put the 10 Mhz
> crystla between low-impedance taps so the xtal has a chance. And instead
> of a single xtal make a proper ladder filter. There won't be more than a
> few dB of loss and the blowby of even a two-xtal filter will be
> dramatically reduced.
>
trying to avoid making a crystal filter as that is what Ray is up against.
I was trying to come up with something less complicated. The NE602
synchrodyne just wasn't sensitive enough to be useful.
>I would love to know of a source. I have less than a dozen of each in
> By the way Chris, do you happen to know of a source of NOS NE604 or
> NE605? They are great for HF and were a tiny faction of the price of
> Analog Devices GHz devices. They even came with pins so you could use
> them without etching a PCB.
>
DIP form, and more in some sort of surface mount package. Best bet is eBay,
unfortunately. They are both terrific parts for making simple homodyne AM
receivers.
Speaking of which, decades ago we would have just whipped up an MC145151
and a crude VCO and have an LO in an hour or so.
You have to be REALLY good to be able to design even simple things with
what's readily available now.
Chris6676 2011-09-15 19:46:07 Chris Trask Re: WWV 10 MHz Receiver
> Connecting the antenna to the receiver I get no lock. WWV is not strong
> enough here. I was trying to decide whether to build a 10 MHz RF amp and
> put ahead of the unit. But I'm beginning to think that may just be a
> waste of time.
>
There's a way of doing this, we just haven't thought of it yet.
Doing things simply is not easy. Just takes more effort.
Chris6677 2011-09-15 20:07:27 Chris Trask Re: WWV 10 MHz Receiver
> > Connecting the antenna to the receiver I get no lock. WWV is not strong
> > enough here. I was trying to decide whether to build a 10 MHz RF amp and
> > put ahead of the unit. But I'm beginning to think that may just be a
> > waste of time.
> >
>
> It would move away from a simple solution.
>
> There's a way of doing this, we just haven't thought of it yet.
>
> Doing things simply is not easy. Just takes more effort.
>
between the gain setting pins. That would satisfy the low impedances that
Bill suggested for making the single crystal a more effective very narrow
bandpass filter.
I'll give this a try tomorrow.
Chris6678 2011-09-15 20:52:48 William Carver Re: WWV 10 MHz Receiver
world and very glad to see they are still with us.
Being limiting amplifiers they'll get "captured" by the strongest signal
they see, so some close-in selectivity would be necessary to receive
WWV, but 10 MHz crystals to make a "preselector" cost peanuts.
Thank you again Dave.
W7AAZ
On Thu, 2011-09-15 at 19:14 -0700, Dave wrote:
>
> William:
> Mouser has both the SA605 and the SA604, but not in DIP packages.
> They are in the SOIC package(surface mount .05 inch spacing).
>
> Dave - WB6DHW
> <http://wb6dhw.com>
>
>6679 2011-09-15 21:17:19 William Carver Re: WWV 10 MHz Receiver
available. Mouser has them in stock (NXP). I get really pissed at the
0.5mm spacing of most chips these days, but can work with SOIC on the
bench.
I will have to order some next time I get something from Mouser.
A three pole 10 MHz filter is a piece of cake. Get 20 pF crystals (NOT
series resonant!) so as a rough approximation the center frequency will
be at 10 Mhz. You can fine tune the filter CF 10 Mhz by changing the
impedance level and bandwidth while modelling it on the computer.
I'd only use the limited (and RSSI output!) of the SA604-5. The detector
at the output is single ended, made for AC-coupled audio: it won't have
dc supply rejection or much dc stability to use its output for phase
locking the LO.
I cheated on LO. I bought one of Kees Si570 kits with my own higher
resolution optical shaft encoder substituted for the mechanical cheapie.
This put a "quickie" LO on my bench in one evening. I'll work out the
code to run that chip with an AVR one of these days so it can keep up
with fast spins of the knob.
I had no trouble making a the sychronous NE602 detector work with gain
of a NE602 mixer and a single J310 ahead of it.
W7AAZ6680 2011-09-16 05:02:49 ehydra Re: WWV 10 MHz Receiver
> William:A similar part is the TCA440. Still available in DIP/DIL.
> Mouser has both the SA605 and the SA604, but not in DIP packages.
> They are in the SOIC package(surface mount .05 inch spacing).
- Henry
--
ehydra.dyndns.info6681 2011-09-16 05:04:53 ehydra Re: WWV 10 MHz Receiver
> Here's a thought: Suppose we took a lowly MC1496. Put a 10MHz crystalOr a µA733 or NE592 ? Maybe to noisy, don't know.
> between the gain setting pins. That would satisfy the low impedances that
> Bill suggested for making the single crystal a more effective very narrow
> bandpass filter.
- Henry
--
ehydra.dyndns.info6682 2011-09-16 06:12:17 Chris Trask Re: WWV 10 MHz Receiver
> > Here's a thought: Suppose we took a lowly MC1496.
> > Put a 10MHz crystal between the gain setting pins.
> > That would satisfy the low impedances that Bill
> > suggested for making the single crystal a more
> > effective very narrow bandpass filter.
>
> Or a µA733 or NE592?
>
>The MC1496 was notoriously noisy, but an RF stage ahead of it would take care of that problem.
> Maybe to noisy, don't know.
>
Chris6683 2011-09-16 08:18:07 Chris Trask Re: WWV 10 MHz Receiver
> > Here's a thought: Suppose we took a lowly MC1496.
> > Put a 10MHz crystal between the gain setting pins. That
> > would satisfy the low impedances that Bill suggested for
> > making the single crystal a more effective very narrow
> > bandpass filter.
>
> Or a µA733 or NE592 ? Maybe to noisy, don't know.
>
I'll have to see if I have any of these in the parts dungeon. If not, I'll try getting samples from TI. I particularly like the NE592N8 due to the smaller package.
Chris6684 2011-09-16 14:44:28 ehydra Re: WWV 10 MHz Receiver
> Looks like the NE592 is more readily available and less expensive. Using that, if you put a 1:1 transformer between the upper gain pins you could then select any number of crystals with a single switch, letting you receive all of the WWV frequencies with little effort.Hm. Is there a simple formula for calculating impedance of an crystal
>
> I'll have to see if I have any of these in the parts dungeon. If not, I'll try getting samples from TI. I particularly like the NE592N8 due to the smaller package.
out of the crystal parameters or a generic way just from the frequency?
Looks like antiproportional to f0 of crystal as a first fit.
- Henry
--
ehydra.dyndns.info6685 2011-09-17 12:10:56 Chris Trask Re: WWV 10 MHz Receiver
> >
> > > Here's a thought: Suppose we took a lowly MC1496.
> > > Put a 10MHz crystal between the gain setting pins.
> > > That would satisfy the low impedances that Bill
> > > suggested for making the single crystal a more
> > > effective very narrow bandpass filter.
> >
> > Or a µA733 or NE592?
>
> Yes, those would work as well if you wanted to recover the carrier,
> then use the MC1496 as a demodulator for the audio.
>
still available from Mouser. Same gain characteristics, but significantly
quieter relative to the NE592. I found some on eBay and they should be here
by the middle of next week.
>I did get the MC1496 circuit to work after debugging a biasing problem.
> > Maybe to noisy, don't know.
>
> The MC1496 was notoriously noisy, but an RF stage ahead of it would
> take care of that problem.
>
I had forgotten that you need to maintain at least 2.7V between the
transistors in the stack. After taking care of that little problem it
worked fine, and I did some testing using an HP3556A signal generator.
Advancing the modulation index using the internal 1kHz tone, the demodulated
waveform begins to deteriorate above 80% modulation due to starvation of the
recovered carrier.
With 330 ohm resistors on the MC1496 outputs, the demodulated 1kHz tone
at 80% modulation was 100mV with -20dBm input power, 40mV with -30dBm input
power. At lower input levels the recovered carrier is starved and the
output signal level decrease rapidly. Based on this, I would elect to use
an audio transformer at the output terminals so as to have a higher audio
output signal.
In terms of bandwidth, changing the RF frequency of the generator showed
that the -3dB bandwidth of the circuit is 2.5kHz, meaning 1.25kHz either
side of centre. Based on this, there does not appear to be any need for
tweaking the crystal, which in this case was a generic 10.0000MHz series
resonant unit of unknown pedigree.
This makes a pretty spiffy little homodyne receiver, but it obviously
needs more gain up front. Using a TL592, NE592, or uA733 with a crystal
between the gain pins will help with the carrier recovery, and a single
stage of RF gain will take care of the RF signal level.
Chris
------------------------------------
Yahoo! Groups Links6688 2011-09-19 17:32:32 Ray Re: WWV 10 MHz Receiver
I connected the output of my FRG7 to the microphone input on my PC and ran SpecLab and Spectran to try and zero beat WWV. But that doesn't work. I see the WWV ticks and announcements but when I turn on my 10 MHz oscillator, I don't see any indication of it6690 2011-09-19 18:10:29 John Kolb Re: WWV 10 MHz Receiver
AM mode won't work.
Putting the FRG-7 in SSB mode, and tuning so the carrier is producing
a tone that shows up
in SpecLab (200 Hz?, 500 Hz?, 1 kHz?) then introducing the 10 MHz
oscillator as an additional
signal might work. Attenuate the oscillator signal to about match WWV.
A sensitive DC voltmeter on the FRG-7 record output should work once
the beat note is down
around 1 Hz.
John
At 05:32 PM 9/19/2011, you wrote:
>Well, I put an RF amplifier ahead of my autodyne receiver but still
>get no reception from WWV. I guess I will give up on the autodyne.
>
>I connected the output of my FRG7 to the microphone input on my PC
>and ran SpecLab and Spectran to try and zero beat WWV. But that
>doesn't work. I see the WWV ticks and announcements but when I turn
>on my 10 MHz oscillator, I don't see any indication of it6691 2011-09-19 18:11:54 Chris Trask Re: WWV 10 MHz Receiver
> This makes a pretty spiffy little homodyne receiver, but it obviously
> needs more gain up front. Using a TL592, NE592, or uA733 with a crystal
> between the gain pins will help with the carrier recovery, and a single
> stage of RF gain will take care of the RF signal level.
>
basically this at the moment:
1. 12V supply voltage.
2. MC1496 biased at 1mA per leg, 10.0000MHz series-resonant
crystal between the gain pins, 600CT:10K audio transformer
connected to output, 4.7K resistor across output (10K)
winding.
3. TL592, inputs connected directly to the MC1496 carrier pins,
10.0000MHz series-resonant crystal between the gain pins,
transformer coupled (1:2CT) to the MC1496 signal pins.
4. J310 input amplifier biased at 20mA, drain connected to the
prinary of a 1:2CT transformer, secondary connected to the
MC1496 and TL592 input pins (see #3).
With a 10.0000MHz input carrier 90% AM modulated with a 1kHz tone,
output voltage is 50mV p-p with less than -60dBm of input power.
There is a slight parasitic oscillation due to building this on a perf
board, which is alleviated with a 22pF capacitor across the MC1496 carrier
input pins.
Chris Trask
N7ZWY / WDX3HLB
Senior Member IEEE
http://www.home.earthlink.net/~christrask/6692 2011-09-19 19:42:08 Ray Re: WWV 10 MHz Receiver
Ray
6693 2011-09-19 19:53:22 Ray Re: WWV 10 MHz Receiver
Do you think putting a 6 or 8 order 10 MHz bandpass filter followed by an RF amplifier fed into this combinati6694 2011-09-19 19:59:15 Graham / KE9H Re: WWV 10 MHz Receiver
You might want to consider a Soft-Rock 40 tuned to 10 MHz, or
other WWV frequency of your choice. It is probably the easiest
and cheapest way to get a limited frequency range, high dynamic
range receiver going these days. If you run it in through the
audio port on your computer, rather than a separate sound card,
you be be able to get going for less than $30.
--- Graham / KE9H
==
6695 2011-09-19 20:13:02 Chris Trask Re: WWV 10 MHz Receiver
> > >
> > > This makes a pretty spiffy little homodyne receiver, but it
> > > needs more gain up front. Using a TL592, NE592, or uA733 with acrystal
> > > between the gain pins will help with the carrier recovery, and asingle
> > > stage of RF gain will take care of the RF signal level.<
> > >
> >
> > Wow. I had no idea this would work out so well. The circuit is
> > basically this at the moment:
> >
>
>RF
> Do you think putting a 6 or 8 order 10 MHz bandpass filter followed by an
> amplifier fed into this combination would be able to receive WWV? Howwould
> you extract the WWV carrier to feed to the frequency counter?It's already sensitive enough to receive WWV all on it's own. You can
>
probably pick off the 10MHz carrier at the MC1496 gain setting terminals.
Chris6697 2011-09-20 07:30:53 Brooke Clarke Re: WWV 10 MHz Receiver
After replacing all the electrolytic caps in my Heathkit GC-1000
receiver it's now in high spec mode for a few hours per day using only
the built-in 2 foot telescoping whip antenna. When there's no signal it
tries 5, 10 and 15 MHz until the 100 Hz sub carrier is detected. This
is about as simple a receiver that can reliably receive WWV/WWVH as can
be built. It does have AGC which if not needed would not be part of the
design. For more see:
http://www.prc68.com/I/HeathkitGC1000.shtml
--
Have Fun,
Brooke Clarke
http://www.PRC68.com
http://www.End2PartyGovernment.com/6698 2011-09-20 10:16:37 Glen Re: WWV 10 MHz Receiver
Have been monitoring WWV (10 MHz) with a simple regenerative
receiver. At the greyline, often the signal is really strong here,
otherwise it is quite weak. My regen has a L-C tune-able tank, so it
is not particularly temperature-stable.
For strong signals the regen will injection-lock to the carrier as
you tune through zero-beat. To do this, regeneration must be advanced
past the point of oscillation. Once locked, it sounds like an AM
receiver, and is operating similarly to a synchrodyne.
If you sneak off a sample of the regen's oscillator to a frequency
counter, you'll have a zero-beat lock6699 2011-09-20 13:58:10 Ray Re: WWV 10 MHz Receiver
I may give the regen a try if I don't have luck with a couple of other things I am trying. I haven't used a regen since 1964 when I had a Heath Kit six meter lunchbox.
Best time of day for WWV here (Phoenix) is from about 5:30pm to 8pm. That is from just before dark until about an hour after dark. It is fairly strong at that time. If the regen will lock for 30 seconds that would be enough time to adjust the counter clock.
Ray
6700 2011-09-21 07:04:31 Tim Re: WWV 10 MHz Receiver
The Time-Nuts and ARRL FMT fanatics use many of the same techniques spun out to the max. Wow, the FMT accuracies available have improved a lot in the past 40 years :-). I remember getting a postcard telling me I was right to better than 100Hz (but not under the 10ppm needed to be listed in QST) and that was pretty good stuff back when I was a kid!
I would be a little reluctant to presume that a regen tuned to WWV wouldn't pick up atmospheric noise spikes that might result in extra counts on a counter which is counting the regen's tank. I know the regen tank has a high Q and you hope there aren't many spikes showing up on the tank waveform, but all it takes is one rapid fade with a lightning crash (maybe less likely in Phoenix than it is here on the east coast where there's always atmospheric noise) in a counting period.
Tim N3QE