Galaxy Melaka No am Mod

[harlyworkr]

I have never seen this one b4. I have no modulation on Am only. I have it everywhere else including lsb, usb, cw, pa and fm. Any suggestions? This is driving me crazy

Thanx
Mike

 

[sp5it]

AM linear modulator to replace.
Very common failure
EPT3600-14B it is TR51
Mike

 

[harlyworkr]

Can you direct me to this please?

 

[harlyworkr]

TR51 in this radio is #A1012 Which is a
Silicon Complementary Transistor Power Amp Driver, Output, Switch. Is this what you are talking about?

 

[sp5it]

Show me photo of mainboard, element side.
That transistor have 12V from power socket on emitter and collector goes to driver/finals.
That is the one you found.
In AM, on collector you should have circa 6-8V, SSB 13.8
When in am is full power supply voltage, it is shorted.
Mike

 

[nomadradio]

Do you have a wattmeter in the coax line with this radio?

It would be helpful to know if the carrier is jammed to 15 or 20 Watts on AM.

This model doesn't have a carrier-power knob on the front. Seeing what happens when you turn that knob on the other models is a helpful diagnostic clue.

But this radio doesn't have that.

Do you know where to find the type number for the printed circuit board? It will start with "EPT3600", followed by two more digits and a letter.

Knowing which circuit board is in your radio could be helpful, as well.

Very good chance that sp5it has the root of the problem already itentified, especially if the AM carrier is over 12 Watts.

73

 

[harlyworkr]

I want to thank you all, the radio has been repaired. It was indeed the 2sa1012 transistor. It is back in it's place of honor.

Thanks again
Mike