Northpoint CBS-1000 help with Low output please?

[Adamf]

Hi all, I picked up a Northpoint CBS-1000 to play with and find AM output is about 1 watt ( no real audio swing) and SSB is like 8-10 watts. I tried to adjust RV4 and the AM coils (L38, L42 etc) but can't raise AM past that. On SSB I tried adjusting RV14 and no real improvement. Hopefully someone out there can help and tell me what to try (some other adjustment, replacing any parts). I would really appreciate it. I know the Northpoint is the same as several other radios (Cherokee, Albrecht, etc). Thanks, Adam in Florida

 

[nomadradio]

Seems to me RV14 sets the SSB peak power limit. AM carrier level should be RV4.

I think.

If it's the same as the "Cherokee" CBS1000.

73

 

[Adamf]

Yes, if you read my post I specifically mention that I tried to adjust those exact trimmers but it did not help.

Anyway, can anyone out there help please? Thank to all who respond. Adam

 

[nomadradio]

I tried to adjust those exact trimmers but it did not help.

Yep, I should read more carefully. Next thing I would try calls for a steady audio tone into the mike, keyed on sideband with the mike gain turned down to 1 or 2 Watts. There are five tuning slugs that affect transmit only. L42, L43, L44, L45 and the one between 44 and 45. My copy of the diagram blurs the callout for that coil. The peak setting for each of these tuning slugs is easier to see on a wattmeter at the low power level. If one or more of those adjustments is not set for peak power, that could cause this trouble.

73

 

[Adamf]

Hi, as mentioned I tried adjusting the trimmers but no help. Does anybody out theter know what else I can try, I am thinking possibly drivers or finals and hoping someone is familiar with this specific radio and can help. Thanks, Adam

 

[SuperLid]

Just part it out and sell it on eBay for ridiculous prices.

SL

 

[AudioShockwav]

Hi, as mentioned I tried adjusting the trimmers but no help. Does anybody out theter know what else I can try, I am thinking possibly drivers or finals and hoping someone is familiar with this specific radio and can help. Thanks, Adam

You adjusted the Variable Resistors but have you tried peaking the Inductors that Nomad called out above?


73
Jeff

 

[Adamf]

Hi Jeff, YES, please read my original post, I SPECIFICALLY mention that. Thanks, Adam

 

[nomadradio]

Is it possible that some prior repair has installed the wrong final transistor?

73

 

[Adamf]

Now that was a good suggestion, I just checked but parts are correct, they match service manual but I am guessing 1 or more is bad. Thanks! Adam