Electrophone GME TX840B SSB Low Power

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Joined: Monday 31st Dec 2012, 11:56
First Name: Warren
Location: Brisbane Australia

Electrophone GME TX840B SSB Low Power

Post by Wazza1954 » Monday 31st Dec 2012, 13:55

Radio Make and Model: Electrophone GME TX840B
PCB Number:
PLL Number: toshiba TC9106BP
Test gear available: Multimeter, Power Meter, Dummy Load
Symptoms: only 2 watts output power on SSB full 5 Watts on AM

What is working:Everything works on the radio it just has low power output on SSB TX

What has been tried: Marked all the Trimmers ( VR's) with marking pen first then tried turning each VR clockwise one at a time while TX on SSB and speaking inti Mic as in a long AHH or Ola, no increase in SSB TX Powr, however full 12 Wall on whistle, obviously the radio has been tuned in the factory with a high pitch audio oscillator, a bit silly when the Human voice is a lot lower in frequency.

Did it suddenly happen ?: The Radio is Brand New out of the box, yes , has been in storage since purchased and first given to Son-In-Law about 10 to 15 years ago, has never been used until a week ago, it is still in as new condition ( Mint Condition.

Anything else that may be of help?: What I need is to know exactly which VR's do what and also Coils etc. Alignment Proceedure, I have looked for this info for hours on the net to no avail, GME website only have the User Manual to download no Service Manual available , the only other solution that I can think of is using a Power Mic to drive it harder as a high pitch whistle into the Mic makes the old dear boogie, Human voice is too low in frequency to drive it like a whistle does, anyway hopefully someone here can suggest a fix, many thanks for reading my post, cheers for now and Happy New Year to all de Wazza

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The Defpom
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Re: Electrophone GME TX840B SSB Low Power

Post by The Defpom » Tuesday 15th Jan 2013, 20:43

I dont have any info on that model myself, but it sounds more like a bad capacitor (or a few of them) in the audio path, effectively hi-passing the audio, cutting off the lower tones.

An incorrect SSB offset calibrations could also be possible, resulting in the frequencies being cut by the IF filter.

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