have 2 980s from 1982,1983
shortly after purchase, yaesu contacted original owners and offered a general transmit board. they asked 9.95$ to cover handling.
easy installation was drop in, solder couple pins into already existing board, connect couple wires. said you needed to use an external low pass filter if ever using the gen for new bands. they had a separate set of wider band pass filter for gen coverage and they would not be adequate for fcc supression.
have the directions somewhere. both still operate properly after all these years
there was a hodge podge mod put together by the ft user group people, but very complicated. probably still have in my ft newsletters from back then
bob donchez
wb3hyb
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On Jun 6, 2020, at 10:21 AM, Dave Thompson <thompson@...> wrote:
?
Fred,
No FT-980 ever had GEN TX unless it was modified by the owner.? I did have one years ago that Phil K4DPK modified? and he did not use the risky Yaesu recommended mod.?
73 Dave K4JRB
-----Original Message-----
From: Fred_N8YX
Sent: Jun 5, 2020 1:30 PM
To: [email protected]
Subject: Re: [Yaesu-FT-980] GEN mode probelm
I did a little research in the Technical Supplement. Short of a circuit malfunction or (unknown) modification, there should be no way that Ham/Gen VFO selection logic should unbalance the various mixers, the Balanced Modulator or alter the BFO frequency.
So, a couple of questions: Did the radio ever work properly? If so, what happened immediately prior to the failure?
One thing I would check is the setting of TC4001 (another member hinted about this). Consult the Technical Supplement for the procedure and the frequency to which it is set. The symptoms are characteristic of a malfunctioning Balanced Modulator; that is, one whose Carrier Null point isn't set properly. Since everything in this rig is tied to a couple of reference oscillators and logically derived from them, we need to figure out if it's an adjustment issue or a logic fault.
73 - Fred, N8YX
