142 gtl no receive

[Handy Andy]

I have not heard your answer on TP3 - do you get anything?

You should - you have TX - but how's your signal route from TR22 2nd IF to it?

That shows up on TP3.

You would also have a voltage on that Test Point in RX - it so it can power (turn on) the Base of TR13 - but if it's above 4V - then TR13 just might need replacement. Its Base might be shot. If it's flat (no voltages) - gotta' find out why you don't have RX voltage, there is a tap off of the RX line R33/R31/R28 nice little squiggly stuff in that spot - but you should have voltages branching off to TR13 from every direction in there - so those 3 resistors will show voltages to TR13 from R33 tapping off that line - being a 1K (or thereabouts)

To help further - we need a Board number.

 

[kaos513]

tp3 reads 1.276 vdc

 

[Handy Andy]

Good sign...

Board number to help guide you?

 

[kaos513]

PC-385AC

 

[Handy Andy]

Ok, I see you're still working on some of those earlier projects...

Might want to back probe the power line FROM the IF coupling coil that feeds any particular transistor in the IF strip (like a Probe to Test voltages per a voltage chart) - to see if one cans' coil has opened up - killing the receive - no power and no signal - but there is enough ambient noise being made and getting sent thru to still allow the rest of the strip to function.

It's why I asked about D15 - The RF Gain feeds voltage to the Base of this "common Base" Amplifier they use as a current amplifier (matching stage) to get the signal to the right level of drive for the IF Mixer to "select" the right range of frequencies that make up that "channel" to discern and get thru.

So big question here to help...

You say you get noise - but do you HEAR any strong signal from another radio set - using a dummy load on THAT set - leaking-or better term, getting thru and into and if you change the channel on the "dummied" radio - so you still hear it?

Because this will lead us into a better path...

For...

• If you can hear another station - weakly - just means the IF is working and we are getting enough RF from that station signal to get processed...

• When you change the channel on the radio sending the signal - and now the signal disappears - then we now know more about the radio you have is capable of hearing and imaging that signal
  • - because we no longer hear the different frequency the other radio is on - so it's not leaking in...

Which helps us develop a better idea of perhaps the RF amp - transistor used and the RF Gain control - are more likely the problems...

See where I'm going with this?

 

[kaos513]

i dont hear my self using my test radio any other stations just here hiss noises

 

[nomadradio]

C193 comes to mind. If it fails open, receiver gain takes a plunge.

Simple enough to test. Touch the leads of a good 1uf 50V cap to the solder pads under C193. If receiver gain jumps up, you found it.

73

 

[kaos513]

Nothing happens

 

[kaos513]

I ohmed out all the cans they seem to be fine

 

[kaos513]

Getting tone now on ssb usb and lsb but very fainted also on am as well now.

 

[Handy Andy]

Ohm'ed out all the cans may be ok or "fine" but are you doing voltage checks?
​

That is what I was getting at, see if any foil traces opened up - or worse - jumped up because the part they feed is blown open...

 

[kaos513]

That will be my next step

 

[kaos513]

Still working on the transistors so far the voltages are correct will continue my journey , still have more to test