Re: Help diagnosing no transmit problem.

Sounds like you might have the dreaded IC ALC problem with
your radio.  When you try to transmit on SSB... look at your ALC
meter.  Does it go up pretty high???

Go into the service menu by pressing the A, B, and C buttons
while turning the radio on.  Go to Menu numbers 11 and 12
(HF IC ALC and V/UHF IC ALC).  Make note of what those
values are.  Trun those value all the way up to 255 and see if
you have any output power.  My radio had this problem... my
ALC meter had like 7 or 8 bars to it.  Turning these up gave me
full power output.

If you get power output... then there are 6 SMD resistors that
need to be replaced.  I'll go into that more.

Mike - N1EVH


On 5/9/2018 11:38 AM, [email protected] [FT100] wrote:
>
>
> My old FT-100D has worked well for years (original owner) and, 
> suddenly, zero output on HF and VHF.
>
> Thinking it was the PA transistors I replaced the MRF755's with NOS 
> ones but problem remained the same.
>
> Using a shortwave radio I hear perfect SSB TX on HF when held close to 
> the unit, and I also hear perfect VHF FM TX when an HT is held close 
> to the set. Levels are VERY low.
>
> The idle current is 1.2A in RCV, which is normal. The current 
> increases to about 2.4A in transmit, both HF and VHF. Bias adjustment 
> in HF has no effect for the PA transistors.
>
> I've removed the PA deck and checked the resistors on the underside, 
> that, for some, were a problem. It 'seems' to me that there is some 
> 'master' shutoff that is closing ALL the transmit higher power 
> circuits in both HF and in VHF/UHF.
>
> Is there a circuit as I described?
>
> Is there a part failure that would cause both RF amps to become 
> inoperative?
>
> What voltages should I look for? I used to be a whiz at this but find 
> that my skills have diminished with disuse!
>
> Bummer.
>
> Any help, or guidance, or reference to other sources, would be appreciated
>
> Mike VE3EQP .....>
>
>
>
>