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Thursday, November 10, 2016

Two Gel Cells and a Heat Sink -- BITX40 Power Hack

I blame Pete for this.  And Farhan.  Pete has been leading us astray with all his talk of high power linear amplifiers ("Two 813s kid, that's all you need!").  And Farhan practically pushed us beyond QRP limits by placing a separate DC power connector for the IRF510 final amplifier on his new BITX 40 Module board.  Farhan writes: 

There are jump-points from where you can add more modules like the DDS, more bands, better audio amplifier, etc. Imagination is your limit. You can separately increase the power amplifier's supply voltage to 25 volts to be more than 20 watts of power : You will have to add a better heat sink. The mods are on the way! (from hfsigs.com)

A while back Chris KD4PBJ sent me some very nice heat sinks -- one of those would fit quite nicely on the PA side of the BITX40 board.  And I just happen to have two 12V Gel cell batteries. One will power the board and the two together will power the IRF510.  With 20 watts out to my dipole I feel confident that I will WIN the upcoming ARRL Phone Sweepstakes (in my category: Homebrew VFO, Northern Virginia).  


  1. Hi Bill,

    Who said" Once you try it, you will never go back?" Frankly why stop at 20 watts? When I get my Bitx 40 the plan is to adapt one of the linear amps I have so it will have an input attenuator pad (only needs about 2 watts) and then I can have 5 watts,100 watts or 700 watts. With another revolution around the sun coming up shortly for me---Life indeed may be too short for QRP!

    Pete N6QW

  2. Going QRO is easy. Just write your wattage up in mW to make it sound big, or kW to make it sound impressive. 20,000mW or 0.02kW. Worth a few more S Points?

  3. I have been having a great deal of fun with the Bitx 40m SSB Transceiver. I find the VCO drifts like crazy, but that is part of the charm. I will add a synth to it eventually.

    Currently I am adding CW to it. Not by tone injection, but by sharing the receiver and having a separate 10w CW transmitter, with RX muting and additional TX/RX switching.

    Bitx is huge fun, thanks for sharing and keep the stories and inspiration coming.


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