[AMPS] 30L1 Grid circuit

[Peter Gerba]

Hi Carl;

Thanks for the reply.

My "Instruction Book" is dated (4th Edition) 15 November 1961.

On my page 1-5 I find "The r-f cable supplied for connecting the 32S-1, 
KWM-2/2A, or KWM-1 to the 30L-1 is 20.5 feet long.  DO NOT cut this 
cable. This length is Optimum to maintain the low-distortion figure for 
which the equipment was designed."

It appears there was a change made between 1961 (round) and 1963.  If you 
have any idea as to the change please tell me as I would like to up-date 
my Amp. I've got several Amps here and the 30L-1 is the one I use the most.

pete, kn6bi

Peter Gerba
pgerba@crl.com

On Fri, 16 May 1997 km1h@juno.com wrote:

> 
> On Wed, 14 May 1997 19:50:32 -0700 (PDT) Peter Gerba <pgerba@crl.com>
> writes:
> >I have a 30L1 question... maybe Tom or Carl can help.
> >
> >I have a Round Emblem model. I was told that the RF cable used to 
> >connect  the Xmiter (KWM2 etc) to the input of the 30L1 was of critical
> length. 
> >It  was explained that the Amp could go into runaway on 21 Mhz and above
> 
> >if this cable was not used.
> 
> That is a bunch of BS Pete.  I use a 6' length of RG8X for all my exciter
> (TS-940) to amplifier work on the repair bench. Never any instability.
> Any one who tells you differently obviously doesn't know that amp very
> well.  The only problem in the 30L1 is with Svetlana ceramic base 811A's,
> they have too much output C to tune 10M. 
> 
> One thing you must remember....the 30L1 was designed for broadband
> service, not just the ham bands. Therefore the input circuit is a
> compromise. The 10M band for instance tunes 22-30MHz and the input
> matching values are a compromise; particularly since only the coil is
> variable. That long input cable was just a bit of a fudge factor.  If
> your amp came from the military, it would be advisable to realign all the
> input coils.  
> 
> Another thing...that amp was made in huge quantities; had a damn good
> reliability record and survived the typical non-technical military
> operator. How many thousand are still in operation??  Tells you something
> about the design! 
> 
> >>From the Collins 30L1 Manual page 1-2, Table 1-1, R-f input cable 
> >426-5079-00,  page 1-0, under "notes" #6 " This cable is furnished with
> 30L-1 in 20.5 FT length.  Do not cut".
> 
> My manual says no such thing as "do not cut" on any page and it is dated
> 1 March 1963. 
> If you have the manual go read a bit further. On page 1-5 it says the
> cable may be shorter for convenience; at least in the Rev here. 
> 
> SNIPS
> 
> 73....Carl   KM1H
> 
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