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July 16, 2024. Baby needs a new pair of shoes!

 I guess for those who "shoot craps" the title is part of a common vernacular associated with that game. But it seems like ham radio is like shooting craps. We always are thinking a new pair of shoes, is like a new radio on the bench. Shoes in ham vernacular of old meant a linear amp following the normal station transmitter.

Something I had been meaning to test was the 40M MMIC CW transceiver. I had a bit of an issue with the original IRF510 (which was removed) and added one small RF amp stage in the transmitter, a BFR106, and changed the final to just the 2N5109. The power output is just shy of 750 milliwatts. 





Using the Reverse Beacon Network on 40M at 750mw, midday, I was spotted in San Jose, CA and Phoenix AZ. The Phoenix spot was about 400 miles away. Of note the San Jose station was W6YX at Stanford University.

Then the test last night at about 2000 PDST on 40M involved running the 40M MMIC at 750 mw and then with a pair of shoes with 25 watts output. 

At the lower power level again spots in the 400-mile range. At 25 watts suddenly N6QW is spotted out to 1500 miles. So, our signal went from 28.75 dBm to 44 dBm. I was driving a CCI amp and at 750 milliwatts of drive had a gain of 15 db. [17 Volts Peak to Peak = 722.5 milliwatts. ]

Thus, the conclusion is that at 750 milliwatts (28.75 dBm) will yield many contacts and a far cry from 200 milliwatts of the RCA transistor transmitter of several posts ago, which is only 23 dBm. Even better is getting the power output up in the 20-watt range which is well worth the effort.  

There are lots of ways to get to 20-25 watts of RF and much depends on your resources and skill set. There are some kit type amps like the Hard Rock 50 and CCI sells a kit (>$100). There are lots of Chinese kits for about $20-25 dollars or you could roll your own. 

Don't overlook brewing up a small tube amp with tubes like a 6DQ6 or a 6DQ5. A 2E26 will get you 15 watts or its big brother a 6146 will certainly deliver 25 watts. 


TYGNYB.

73's
Pete N6QW



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