[Collins] 30L-1 Repair

[w7fe]

You are quite correct, Tom, to suspect a component issue in the 20M input 
circuit, most likely the capacitor.  It is not uncommon for those capacitors 
to wander out of tolerance, usually well below the stated value, to the 
point that the circuit will no longer resonate in the 20M range.

Another possibility is that sometime in its life, your 30L-1 might have seen 
an instance of input overdriving or applying a non-20M signal while the 
bandswitch is set to 20M (nobody would ever do that, would they? --  hihi), 
either of which could have damaged the capacitor  --  or possibly the 20M 
bandswitch contacts.  You might want to check them out while you're in 
there, too.

73 de Stu, W7FE
Henderson, NV

----- Original Message ----- 
From: "Tom" <url4603rd at comcast.net>
To: "Collins Mail" <collins at mailman.qth.net>
Sent: Thursday, July 03, 2014 2:30 PM
Subject: [Collins] 30L-1 Repair


> Hi All,
>
>     Posted here before about this but have a follow up question.
>
>     I've been told that the problem is not the tuned input ckt. but the 
> 811 tubes. I fully admit that I'm not an expert on RF Amps, BUT it has 
> good output on all bands except 20M. The tuned input on 20M will not go 
> below 4 or 5 : 1 , all other inputs go to 1:1.  I kind of think that if 
> the problem is isolated to just the 20M tuned input that the logical 
> "suspect" is one of the caps in the tuned input ckt. or am I incorrect and 
> the 811's are the suspect?  I "do realize" that the 811's are easier to 
> change out, but it still doesn't compute in my ole brain.
>
>      Thanks for everyone's feedback on this.
>
> Tom W1ALZ
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