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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