Re: Help diagnosing no transmit problem.

All I know is... I had the same problem that he had back in like
Dec 2001.  I was using the radio... and then all of sudden... no
output power on ANY band.  For my radio... the finals were fine.

Now... he said he was thinking it was the PA transistors... so he
replaced them... and still nothing.  So my guess would be that
his other PA transistors are still fine.

So... this is why I said to transmit and look at the ALC meter.
If the ALC is messed up causing no output power... then you
may not get the results you're expecting when you try to adjust
the bias on the new transistors.

Since I had my radio repaired back in May 2010 (yes... I went
just over 8 years with the radio not working until I found out
what was wrong with it and what fixed it)... quite a few other
people in this group have had no output power on any band,
their ALC was high, setting Menus 11 and 12 in the service
menu up to 255 gave them full power output... and replacing
those 6 SMD resistors fixed their problem.

Mike - N1EVH


On 5/9/2018 12:29 PM, Mike Maiorana [email protected] [FT100] wrote:
>
>
> Mike,
> He said that the bias adjustment for the finals didn't have an affect 
> on the supply current. If this was the ALC problem would it behave 
> like that?
> Regards,
> Mike M.
> KU4QO
>
> On Wed, May 9, 2018 at 12:15 PM, '[email protected] 
> <mailto:[email protected]>' [email protected] 
> <mailto:[email protected]> [FT100] <[email protected] 
> <mailto:[email protected]>> wrote:
>
>     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]
>     <mailto:[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 .....>
>>
>
>
>
>
>