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Sunday, May 27, 2012

Homebrew QRP Fun on 75 Phone

OK, I take back all of the bad things I said about the 75 meter phone band. I recently finished work on my Kick Panel 75 meter DSB rig.  Last week I took portions of the multiband antenna that Solder-Lexicographer Steve Silverman sent me and turned it into a 75 meter dipole.  It is now suspended in the trees above my house.  With some trepidation I ventured out into the 75 meter ether.  And, to my surprise I found friendly hams willing to give my 3 watt DSB signal a chance.   The first contact was with K2WS.  I had called Billy into the shack, thinking that I was just going to show him the beauty of a Direct Conversion receiver.  To my astonishment I found K2WS calling CQ!  On 75!  Who knew?   I gave him a call and -- BINGO -- we had a wonderful QSO.  Alan is at the other end of the tech spectrum -- he was running a Flex Radio.  With that rig's panoramic display he was able to SEE that I was running DSB.  Very cool.  Billy was duly impressed. 

Yesterday morning I ran into a very congenial bunch of guys from the Gallups Island Radio Club.  They welcomed me into the group and allowed me to join in the roundtable.  Thanks guys! 

Then came the icing on the cake.  This morning I heard a familiar voice calling together the Mid Atlantic chapter of the Quarter Century Wireless Association.  Could it be?  Yes indeed, it as an old friend, Ray, a guy who had brought me into the QCWA group during our previous stint in Northern Virginia. I checked into the net and had a great time. 

Above you can see the latest version of this long-evolving rig.  It has a built-in speaker.   Below you can see it with the top off. 

Three cheers for 75! 

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  1. Now there's something you don't see every day! Upper left corner of the open-box picture.

  2. "Film at 11"

    73.......Steve Smith WB6TNL
    "Snort Rosin"

  3. Now I have to redouble my efforts to get some DSB on 75M Bill. I've already built a DC receiver using an ADE-1 mixer which will work a treat when I can get the VFO to behave. After that, all I have to do is squirt some audio into the DBM, add a driver and IRF510 final and - badabing badabong - a DSB rig on 75.

    After seeing your Kickpanel DSB rig I have begun my rebuild of the VFO in my little monster and hope to join you on 75M DSB soon!



  4. Hi Bill -

    Just finished rebuilding the VFO in my direct conversion RX, and it's working gangbusters on 75/80. It has a VFO tuned by an air-spaced variable cap and using 2 x J310's feeding an ADE-1 diode ring mixer package. The AF amp is 2 x 2N3904's in the preamp feeding an LM380 (sorry about the chip) and it sounds really, really good. I'm sitting here marveling at how good a simple direct conversion receiver can sound. There are no microphonics, no broadcast band breakthrough and the VFO is stable.

    The next steps will be to add a mic preamp and a driver and IRF510 final, and 75M DSB here we come.

    Thanks for the inspiration Bill!



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