2103	2008-09-22 09:43:17	ter753	micro R1 receiver
Message	Date	From	Subject
I have mislaid my copy of emrfd and was wondering if anyone could post or e-mail me the schematic.Thanks!, terry. ter753@yahoo.ie
2105	2008-09-22 19:33:54	timshoppa	Re: micro R1 receiver

2108	2008-09-22 21:39:08	Rick	Re: micro R1 receiver
The August 1992 article describes the original R1 receiver. It is considerably more complex than the simple microR1 described in chapter 8 of EMRFD. I occasionally re-read both descriptions, and often learn something new while thinking about them--even though I wrote them. I always learn something when I re-read Wes and Bob's sections of the book. I approach direct conversion receivers the same way I approach playing scales on the violin: the simplest ones are always worth reviewing, and there are more complex ones that I am not ready to tackle, yet. I have played with the microR1 circuit many times over the years, and each time I build it a little differently. I just posted a new file on this site that describes a recent variation I built for my RF Design class at Portland State University. The new file does not include any information on the input double tuned circuit, because that was left as a design exercise for my students. Note that the link on the output of the double-tuned circuit is the DC return for the diodes in the mixer, so if you change the input circuit be sure to provide a path to ground at that point. Best Regards, Rick kk7b
2111	2008-09-23 05:12:36	ea3ghs	micro R1 receiver with RA3AAE mixer
Hello, Maybe can be interesting for someone. In my local QRP club we have only 7030khz xtals. I was very interested in digital modes in the 20 meters band, 14070 kHz. One year ago I copied the Rick's receiver but with the RA3AAE or/and Marvin Cohn from Westinghouse doubler mixer. The schema can be seen here: (page 6) http://ea3ghs.googlepages.com/TresReceptoresTresFilosofias.pdf I have received an Australian station (20000km!!) with a small dipole in MFSK16 mode. 73/DX Eduardo EA3GHS
2116	2008-09-23 10:34:35	Rick	Re: micro R1 receiver with RA3AAE mixer
Muy Bueno Eduardo, This is an excellent, well-written article with many interesting ideas and insights. I highly recommend it to anyone in the group with any Spanish at all. Even if you don't read Spanish, the schematics are well worth studying. There are some ideas here I will try the next time I build a simple receiver. Note that the input double tuned circuit values in Eduardo's 40 m version are appropriate for the microR1 schematic that I posted. Muchas Gracias y 73, Rick KK7B > The schema can be seen here: (page 6) > http://ea3ghs.googlepages.com/TresReceptoresTresFilosofias.pdf > I have received an Australian station (20000km!!) with a small dipole > in MFSK16 mode. > > 73/DX Eduardo > EA3GHS >
2117	2008-09-23 11:24:37	k5nwa	Re: micro R1 receiver with RA3AAE mixer
At 12:34 PM 9/23/2008, you wrote: >Muy Bueno Eduardo, > >This is an excellent, well-written article with many interesting >ideas and insights. I highly >recommend it to anyone in the group with any Spanish at all. Even if >you don't read >Spanish, the schematics are well worth studying. There are some >ideas here I will try the >next time I build a simple receiver. > >Note that the input double tuned circuit values in Eduardo's 40 m >version are appropriate >for the microR1 schematic that I posted. > >Muchas Gracias y 73, > >Rick KK7B > > > The schema can be seen here: (page 6) > > > <http://ea3ghs.googlepages.com/TresReceptoresTresFilosofias.pdf>http://ea3ghs.googlepages.com/TresReceptoresTresFilosofias.pdf > > I have received an Australian station (20000km!!) with a small dipole > > in MFSK16 mode. > > > > 73/DX Eduardo > > EA3GHS > > I like circuit #1, and #2, I have always liked balanced mixers but generally I make it more complicated than #1, the author was looking to simplify the circuit and he succeed. In place of the 47 ohm resistor in the emitter I like to use a FET circuit being a constant current source, that increases the gain of the mixer. Usually I feed the differential RF signal to both bases and the LO as a separate circuit to the FET in the emitters. It's quite a bit more complicated but it works slightly better. Good choice on the BC547 transistor, that is a very low noise transistor but inexpensive, very few circuits use that transistor in the U.S. which is a shame. I have about 500 of the BC550 and BC560 transistors. (even more quiet) The 2N4401, and 2N4403 are also excellent and underused. Is the over-coupling of the two input tuned circuits so you can have broader bandwidth? The one thing I question is the diodes clipping the output to +- .7V that is way too low so it limits how strong a signal the circuit can handle, the sound card can usually handle about +- 1.25V. Very good circuits. Cecil K5NWA www.softrockradio.org www.qrpradio.com "Blessed are the cracked, for they shall let in the light." [Non-text portions of this message have been removed]