Service Manual for Palomar SSB-500?

[Robb]

Local guy wants me to work on his radio and fix a few things. Yes, it needs caps too. But I cannot seem to find a service manual for it. CB Tricks has the schematic for it; but no SM.

Anyone have one, or a link to one?

Thanks!

 

[loosecannon]

not sure but i think there were two different versions of this radio.

if it's the one that's like an 858 SSB chassis with an MC145106 PLL in it then i have the SAMS for it. #284
let me know if this is the right one.
LC

 

[Robb]

Yep, it has the 145106 pll in it.
Thanks!

AM receive is dead; tx is ok.

Any particular tips about this one?

 

[Robb]

Ha! Took me long enough to realize that this is basically the same chassis as a TRC-449. Duh! Difference is, that it uses a 145106 for the pll stage instead of a 858 pll.

Still would like to get that SM if you have it available.
Can you PM it to me LC?
Would appreciate it.

Never seen one of these until just recently. Thing is all hacked up. Still no AM receive.

Handy Andy, have you any experience with this little bugger?

 

[kopcicle]

EL CAPO , unit_399 is the guru here (understatement) but in his absence ...

first , http://unit399.wixsite.com/858ssb
Then I'll dig through my shiznit for the schema and "
follow along at home"
Basics first
AM osc?
Bandswitch/deoxit
DC test points

More when I'm not running out the door...

 

[Robb]

Quick viddy to show the device under test.

Here are a couple of snaps of the PLL section as per request:

 

[loosecannon]

what the heck blew out the back of that pot!? LOL
LC

 

[ExitThirteen]

Check the mode switch, and see if it's getting voltage thru it in AM mode. Let us know how you get on.


~Cheers~

 

[Handy Andy]

He prolly' got it from a guy that ran an amp...

This one is unique, the AM IF is interesting...

Ok, for some simple checks - Locate IC3 and probe Pin 7 - it's the mixer for Mic Amp - but it "taps" the line for AM mode. But that same line use the AM Detectors near the back of the radio to help determine AGC values - it affects the amount of signal that AM RX uses when strong AM signals are present.

Make sure all the caps are in correctly - ANL inclusive - can may your day because all signal goes thru that filter section. So if that cap isn't right you will not see any signal...SSB is a totally different section.

This whole mess with AM may be from his efforts to keep RF out of the radio from a leaky amp or noisy shack - that's a lot of RF and hash chokes in there.

There is a scary section for the radios' AM modulation using TR22 TX which INJECTS past TR21 but AM and SSB gets amped by TR21 in RX.

So if they modded anything about the area of the Audio amp - they may have been trying to run it full throttle for max swing stuff.

If you can get at TR22 - pull it - see if AM RX returns - for the MODE switch overrides the RX/TX of TR21 stuff

 

[Robb]

@ L.C.:
LOL LC; it is a subbed pot w/ inner and outer 100k pots. The stock squelch pot was ditched. The switch was removed just to use it for adding a variable output along with replacing the stock squelch control.
Told ya this radio is a real hack job . . .

@ Xit13:
Haven't tested the mode sw as yet.
Don't need to, as it does tx in AM mode - just no AM receive.

@ H.A.:
Just recapped the radio, so 30% were outside the acceptable ESR values. Some good info about IC3, will have to check that all out.

 

[Handy Andy]

@ H.A.:
Just recapped the radio, so 30% were outside the acceptable ESR values. Some good info about IC3, will have to check that all out.

The down and dirty way of TR22 - is similar to the Limiter TR32 in Galaxy radios - they always pull that to obtain max mod - but if that kid did some kinda' mod to the clipper/limiter - redirector TR22 - it can toggle on and if it's blown can send a "pinch off" signal into both the AN612-style section as well as the Audio Amp line - forcing full quieting.in RX but screaming audio in TX mode because AM mode will push current into TR22 all the time - whether you have AM mode on, and you're in TX or RX - Receive can't get past it.

That's is the crux of a quirk I had to deal with in a 858-syle chassis a long time ago - so to see all those "Chokes - bought me to think this may be similar problem with TR 22.

Besides - it is a quick check - so pull of see if RX returns, else - replace TR22 if it don't - put it back in there and continue

 

[loosecannon]

Robb, i'm squarely in the shotgunning/guessing phase right now, but my first places to check out would be the mode switch and the relay. especially the relay!

look at the schematic on CBT and look at the lower right corner.
see K3?
it's a relay contact that switches between RX and TX in AM mode.
it switches the audio from T1 to either the driver and final section or to the speaker.
if this contact was making good contact in TX but not in RX, i could see this affecting your AM receive but not the AM TX.
you should be able to jumper across the RX contacts and see if that restores your AM RX.
again, this is a guess.
LC

 

[kopcicle]

^^^^^^^^^^^^!

 

[Robb]

Robb, i'm squarely in the shotgunning/guessing phase right now, but my first places to check out would be the mode switch and the relay. especially the relay!

look at the schematic on CBT and look at the lower right corner.
see K3?
it's a relay contact that switches between RX and TX in AM mode.
it switches the audio from T1 to either the driver and final section or to the speaker.
if this contact was making good contact in TX but not in RX, i could see this affecting your AM receive but not the AM TX.
you should be able to jumper across the RX contacts and see if that restores your AM RX.
again, this is a guess.
LC

Doesn't SSB use the same relay for receive? Because it receives fine in SSB mode.

 

[Handy Andy]

I'm still here, but If TR22 shows ok, the only other amp I see that even uses this "pole" of MODE for AM is TR7 - right off the IF filter FT001. D7 should be checked - tested - both Band and Anode in TX mode and RX mode - if D7 goes "off" in RX mode - there may be a problem related to the RF diode routing used to send AM or SSB IF thru that Crystal Filter FT-001.

Now there are RF switching diodes used to "quench" a circuit using AM mode, but there is also in interesting way to default to AM if you're not in the other two modes.

TR41 uses S402 to "starve" the AM Oscillator TR39 - so if any sort of TX/RX Clarifier Unlock has been done - it can affect the AM MODE to NOT even allow TR39 to work. TX may work because it receives power to resonate - but if the TX voltage is supposed to switch over to RX - and there should be about 4.5 to 5 volts to power the Base of TR39 thru a 11.2850MHz Xtal- So check to see if that RX Clarifier voltage gets to AM TR39 thru L23.

Now if L23 does not get power in RX mode then D29 or D30 and the potential damages from a botched Unlock conversion may need to researched.