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Thomas Walsh
Extra Class
W2CO Ham Since 1969
United States

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Other Callsigns
WN2BXS 1969-71, WB2BXS 1971-85, N0DYR 1985-95, W2CO 1995-present, also GROL w/Ship Radar 1991

My Ham Radio Interests
Active in HF CW, HF Digital Modes, HF DXing, Satellite operations - VHF/UHF/MW now active on ISS APRS packet, Satellites worked in the past - AO-10 mode B, AO-13 mode B, AO-40 mode U/L/S.

Collins, Drake, Kenwood, Icom, Yaesu, Ten Tec, Hallicrafters, Alpha among others.

Other Interests
Classic Cars and Motorcycles, Original Music Composition

Check out our music page at

We're #2 for instrumental locally

Some of our music has cw and other ham radio sounds incorporated into the songs. See if you can copy them.


Repairing Icom IC-751A

From W2CO

12/1/2019 5:26:19 PM (2 comments) Add a commentAdd Comment

Upgraded rf amp to J310 jfets in RF board, PLL good except missing 2lo output, changing 2sc383's in 2lo output circuit.
Pics to follow..

Read the 2 comments after the break below.


by WB4IUY 12/7/2019 7:18:03 PM

Great t hear the progress. What was the improvements with the J310's?


by W2CO 12/8/2019 8:33:15 AM

The reasons for J310 is #1 the 2sk125's are no longer made and are practically unobtanium. I found a few but will not pay the 15-20$ a piece for them. #2 The J310 has a higher D-S max voltage, up to 60v vs. the 20v the 125's had. #3 the J310 have a bit more gain and better noise figure than the 125's. Don't forget the original parts are over 30 years old now, There was no warning.. Actually one of the 125's blew and took out one of the 8v regulators. That was the first problem. The symptom was the RX front end went completely dead! There are two amplifier sections, one for rx and the other for tx. The J310's require some pin swapping, ie; the gate is on the end, (not the middle pin) so one must swap the leads to match the circuit. I used thin heat shrink to avoid them from shorting out. If I remember correctly, the source and gate pins get swapped so the gate is middle, then align the backwards to silkscreen to get S G D .

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