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Vintage Amateur and Military Radio Amateur/military receivers and transmitters, morse, and any other related vintage comms equipment.

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Old 29th Jan 2022, 1:42 pm   #1
John M1JWR
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Join Date: Nov 2018
Location: Carlisle, Cumbria, UK.
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Default PTBM 125a4x eeprom fitting

Hi
Long story with a simple question, i have a tristar 777 that i bought several years ago, when i bought it, it was completely dead at that time i had to replace the vco block, 2sd325 voltage regulator plus coil and diode involved, channel selector and mode switch (big job), do have a scrapper so that was handy,after all that it wouldent switch to tx, initally blamed the tx mixer so replaced that, not the fault, in the end it was the rx/tx switching transistor, anyway after another 3 years lying in a cupboard, ive decided to have another go at it, there was a couple of things i diddent finish off, it is spot on on rx, on tx i had it equal on all 3 blocks but remains a bit low on ssb power out put, that will come in time, i call this a practice radio, its in exellent condition on the outside, but somebody messed with it big time on the inside, so mostly there now.in the case of the mode switch i couldent get a 5 position one 3 tier like the original so had to draw out where all the wires went and a friend gave me a 6 position one so had to wire it with one row blank so to speak and that works fine.
the question is i have a rather nice eeprom that was removed from the scrapper years ago, i know it works, it does ss/low to and including hi bands plus uk 40 plus alphas, when i removed the prom i did draw down all the pins etc where the wires went apart from one which is a white wire which it seems i wasent too clear about, my writing says white to area of r98, i am assuming that its the live feed and the only thing in that area is pin 6 which comes from the vol on/off, the black wire goes to r3 which i think is ground, just need confermation on the white wire, many thanks
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Old 30th Jan 2022, 1:47 am   #2
John M1JWR
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Default Re: PTBM 125a4x eeprom fitting

cancel that, prom is fubared
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Old 30th Jan 2022, 12:59 pm   #3
John M1JWR
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Default Re: PTBM 125a4x eeprom fitting

well radio was fine 3 years ago, dosent work now either, will do some voltage checks and report back, so may be a different subject matter if it comes to that, will report back, switches on, no rx.
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