KE7GKM VRX-1 Update

As you may recall in a previous post last December, I made a QSO with, then received a cool e-mail from Bob KE7GKM about his quest to make 100 QSOs using a lashup of a VRX-1 and a homebrew QRP transmitter. Bob kindly sent me an update on his progress:

Hi Jason,

This is just a brief up-date.   I now have a total of 160 qsos with
33states using ur vrx-1.  fun!   My last 60 qsos hv bn on 20meters.

It is too bad that the  vrx-1 “bag of parts kit” is no longer
available to those with weak/novice junk boxes.   (It is hard to do
one-stop shopping when toroids are needed)

My experiment to combine some aspects of the vrx-1 with Campbell’s
Binaural I-Q Receiver worked, but not very satisfactorily  as there
was too much noise and the channels were not balanced.

My next project is to construct a better (I am still amazed at the
vrx1) receiver which is essentially discrete.  Any leads?  I am
thinking along the lines of borrowing the rx design from NorCal’s
2N2/XX Transceiver .


This   P S.  is just a reminder to you of my set up.   Besides the VRX1 I use a
modest transmitter which serves as the exciter at about 1/4 watt.   It
uses a  XFO. My ICOM  or a
frequency counter is used to set the TX and RX frequencies, giving
a 600HZ offset.  My straight key feeds a double pole relay with one
line to the TX and the other to the side tone, which presently is produced by an
HB practice code oscillator.   [3 toriods, 3 bipolar transistors, 1

The  exciter drives  a W6JL RF amp.  The June QST article on this amp
and the chance construction of the  VRX-1 formed the imputes to
complete my HB station.  [4 toriods, 2 bipolar transistors, 2 mosfets,
pwr from a wheelchair battery. ]   (Unless one is very careful,  one
should have spare mosfets handy.)  I was attracted to the push-pull
design, as I had wished to make  a 5 watt push-pull tube amp some day.

I hv  2 fully home brewed stations — one fer 40m es one fer 20m.  They
are essentially the same except for filters and antennas.   When
convenient I like to make two of each home brew project so that I can
judge them by comparison. See attached file for pic of 40 m rig
followed by 20 m rig.  The attache case yields lots of room fer mods,
etc.  Both are portable, using either wheel chair batteries or
emergency automotive starter batteries (presently).  The efficiency of
the TX amp is (presently) poor.

Since we last had a QSO, he has doubled his amount of QSOs. Impressive! He’s also the first person that I’ve heard of who has actually modded a VRX-1 for a band other than 40 meters (I added quite explicit instructions on how to do it in the documentation, so I hope there are more out there). Congratulations Bob on your great homebrew accomplishments! They’re certainly inspiring!

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