EMRFD Message Archive 14309

Message Date From Subject
14309 2017-09-17 11:15:40 bwbangerter AD8307 based power meter

I am planning to build an AD8307-based rf power meter, as many others have done.  To this end, I bought ten of these chips, from China, on ebay, at a price that seemed too good to be true.  Alas, they are certainly not what they are claimed to be - no surprise.  The AD9308 from Mouser or Digikey in unit quantity is $13 and change.  Ouch.  Has anyone found a less costly yet reliable source for this part?


Ben, K0IKR

14310 2017-09-17 12:39:51 Gary Re: AD8307 based power meter
Are you sure?
My chinese ones worked fine.
73,
Gary


Sent from my iPhone

14311 2017-09-17 12:59:45 Phil Sittner Re: AD8307 based power meter

I can second Gary's comment having made purchases three of four times and all of them performed well.

Phil, KD6RM


14312 2017-09-17 16:52:47 bwbangerter Re: AD8307 based power meter
It appears I spoke too soon.  I purchased ten parts, in SOP-8 packages, in tape and reel.  I mounted two parts on dip carriers, using antistatic procedures and a grounded soldering iron. In my test circuit, the first sample gave an output of ~ 200 mV independent of rf input level (below 0 dbm) and the second gave 0 mV.  After seeing your responses and being encouraged to try another sample, the third time was the charm.  That one performed perfectly.  I'm pretty sure I handled all three samples in the same way.  Odd.

Ben, K0IKR
14313 2017-09-17 18:59:37 Gary Re: AD8307 based power meter
I would check the soldering.  I have had probs myself!  My old eyes!
73,
Gary
WB6OGD


Sent from my iPhone

14314 2017-09-17 19:09:05 Ken Chase Re: AD8307 based power meter
Yes the chinese ones do work, at least the 30 I bought for a buildathon.

73

VA3ABN

14315 2017-09-17 20:21:32 Dana Myers Re: AD8307 based power meter
14316 2017-09-17 20:27:50 K5ESS Re: AD8307 based power meter

I think why so many of these parts are available at very low price is that they were manufactured some time ago and are not ROHS compliant.  Large manufacturers can’t use them if they have to meet ROHS requirements. 

Mike

K5ESS

 

14317 2017-09-17 20:33:47 DuWayne Schmidlko... Re: AD8307 based power meter

One of the explanations I read was that many of these type parts are not RoHS compliant, and they are were not able to sell them to new equipment manufactures doing business with EU countries.  Another is that they were left over from manufacturing runs and sold to resellers.  Either way I am not complaining about the ones that I have gotten for a fraction of the normal price.

DuWayne KV4QB


14318 2017-09-17 20:38:40 Dana Myers Re: AD8307 based power meter
14319 2017-09-17 20:39:16 Dana Myers Re: AD8307 based power meter
14321 2017-09-17 21:21:30 K5ESS Re: AD8307 based power meter

ROHS compliant means (maybe among other things) that there is no lead in the product. These cheap items are electrically identical to ROHS compliant parts but the leads are not tinned with lead bearing solders.

Mike

K5ESS

 

14322 2017-09-17 21:47:09 DuWayne Schmidlko... Re: AD8307 based power meter

The parts were within spec when manufactured, but may have been manufactured before the RoHS requirements. The issue with non RoHS is usually that the leads are tinned with lead, but that does not make much difference to most hobbyists.  Some of these are from auto insertion tape reels. The manufacture may have had an order for 2000 items but had to buy a reel of 2500 parts to get a price break. After the run they sell the unused parts to re-sellers who cut the tape reel in to small lots, and sell to the hobby market.

DuWayne KV4QB


14323 2017-09-17 22:02:35 Dana Myers Re: AD8307 based power meter
14324 2017-09-17 22:19:28 DuWayne Schmidlko... Re: AD8307 based power meter

Another thing specific to the AD8307, is that it is a fairly old device.  For most new applications it has been replaced with the AD8310.  Which has slightly different but mostly  better overall specifications.

DuWayne KV4QB


14325 2017-09-18 00:30:40 gi0gdp Re: AD8307 based power meter
Hi Ben,
I'am fairly certain that AD make a point that if the at rest output voltage is greater than 200 mW it's
because you have a bad pcb layout. Where all 3 built on different chip carriers?, the thing is the problem
could equally have been with decoupling caps,
Geoff
GI0GDP
14326 2017-09-18 03:44:18 Steve Dick Re: AD8307 based power meter
No, but if you’re starting from scratch and making a new layout, you might want to consider using the AD8310. It only cost $9.82 instead of $13.14. It is a newer generation device, having a 95dB dynamic range and a built-in output buffer amp with better linearity at slightly less bandwidth. It has  DC to 440 MHz operation, ±0.4 dB linearity compared to the AD8307, which is spec’d at  DC to 500 MHz operation, ±1 dB linearity Unfortunately though, it does not have the same pinout as the AD8307.
 
Steve K1RF
 
14327 2017-09-18 13:36:10 byteboy12 Re: AD8307 based power meter
A complete module:

http://tinyurl.com/ycqgh242

Henry - PA0HJA


On 18-9-2017 12:44, 'Steve Dick' sbdick@optonline.net [emrfd] wrote:
No, but if you’re starting from scratch and making a new layout, you might want to consider using the AD8310. It only cost $9.82 instead of $13.14. It is a newer generation device, having a 95dB dynamic range and a built-in output buffer amp with better linearity at slightly less bandwidth. It has  DC to 440 MHz operation, ±0.4 dB linearity compared to the AD8307, which is spec’d at  DC to 500 MHz operation, ±1 dB linearity Unfortunately though, it does not have the same pinout as the AD8307.
 
Steve K1RF
 
14328 2017-09-18 15:55:33 Steve Dick Re: AD8307 based power meter
That AD8307 module is an excellent value and the AD8307 is already soldered in for you. Just be cautious of the following: Depending on vendor, the input terminating resistor may be 100 ohms instead of 50 ohms. Measure it with an ohmmeter. If it is 100 ohms, parallel it with an 0805 size SMD 100 ohm resistor and verify the parallel combination is 50 ohms. Or just replace with a 50 ohm resistor. The board also does not have output buffering if that is needed in your design.
-Steve K1RF
 
14330 2017-09-18 16:56:57 K5ESS Re: AD8307 based power meter

Steve,

The module is actually an AD8310 module which I believe incorporates an output buffer on the chip.

Mike

K5ESS

 

14331 2017-09-18 21:47:37 bwbangerter Re: AD8307 based power meter
I want to thank everyone who has contributed to this thread.  I appreciate your comments and suggestions, and believe I have learned quite a lot about the sources of the attractively priced parts available from Asian vendors. The two failed parts may have been outliers, and perhaps victims of my mishandling.  I now have several AD8307 chips that are working properly, and my project is moving forward!

Ben, K0IKR

14332 2017-09-19 03:39:43 Steve Dick Re: AD8307 based power meter
Thanks Mike – missed that. Think I’ll buy one to try out
 
14333 2017-09-19 04:03:58 Steve Dick Re: AD8307 based power meter
The seller for that AD8310 module, Ali Express, wants your cell phone number or doesn’t let you proceed.  I don’t like that. Ebay also has it. There are 7 listings. Six of them all have the same blurry picture of the module.  One seller has an in-focus picture but is charging twice as much as the others.  I went with one of the ebay ones.
-Steve K1RF
 
14339 2017-09-20 20:35:47 Jim Strohm Re: AD8307 based power meter
Steve,

How do alibadbad verify your celphone number? 

800-555-1212 is a perfectly good phone number to give out.

73
Jim N6OTQ

14340 2017-09-20 21:46:30 Phil Sittner Re: AD8307 based power meter

I have had requests for my phone number when ordering PC boards from offshore vendors. They provide the number to DHL for notification purposes. Is it possible that the same condition exists in your case?

Phil


14342 2017-09-21 11:42:36 Jim Strohm Re: AD8307 based power meter
Does DHL actually come to your shipping address to deliver, or does the package show up in your mailbox?

USPS doesn't care about your phone number for routine deliveries, and anything that ends up in the hands of USPS -- the original shipper's chain of custody ends when the packages goes into USPS' hands so they would never need your phone number.

Except to sell it to the phone SPAMmers, of course, who pay good money for live numbers when bundled by the millions.

73
Jim N6OTQ

14343 2017-09-21 12:47:28 Phil Sittner Re: AD8307 based power meter

Jim-

DHL does actually show at your doorstep and calls prior to attempting the delivery. They typically make the delivery one day prior to what they tell you.

Phil


14348 2017-09-23 03:33:04 Steve Dick Re: AD8307 based power meter
Hi Jim. The point is, They shouldn’t be asking for one to prevent ordering to proceed. It should be an optional entry, or they shouldn’t be asking at all.
 
14349 2017-09-23 09:17:43 Raj Re: AD8307 based power meter
Here in India/Asia:

They ask for it to message you the order details. Non availability or delays or refunds etc.
They print it on the label for the delivery chaps to call you if they can't find you or no one is home.
If there is a customs problem they call you.

Generally speeds up things!

Raj

At 23/09/2017, you wrote:
 

Hi Jim. The point is, They shouldn’t be asking for one to prevent ordering to proceed. It should be an optional entry, or they shouldn’t be asking at all.
 
14350 2017-09-23 10:00:51 Jim Strohm Re: AD8307 based power meter
Hmm, they "need" a phone number.  That's kinda like requiring an email address when one is unnecessary.  For that, I always give something like "root@dev.null" or "127.0.0.1@dev.null," both of which resolve as "good" email addresses, even though both merely loop back to the local console of the idiots who "need" an email address.

Thus, 800-555-1212.  Or the number of the local McDonald's.  Or the switchboard at Congress.

And for the "mortar and bricks" retailers who need a zip code at the checkout register, if I'm not a frequent customer with them, I give them "90210."

It is worth mentioning, back in the 80s when I sold computers over the phone, I did have a few good customers in 90210.

73
Jim N6OTQ

14351 2017-09-23 19:13:46 augustinetez Re: AD8307 based power meter
We're starting to get a few businesses in Australia that are asking for phone numbers etc.

I flatly refuse to give it to them and make them the offer of selling me the item without those details or losing the sale altogether.

Can't say that I have struck it in online purchases yet, but my policy is not to deal with places like that.

Terry VK5TM