The first sensible step would be to measure the parasitic resistor values.
The second thing would be to accept that Chinese 811A's will never be
completely stable on 10-15M
The third would be the ability to understand that 2dB additional NF on
10-15M might only make a difference once in your lifetime since modern
radios are far more sensitive than real world requirements. OTOH if you
undertake 10M EME it might make a difference but you would also need a real
amp(-;
Carl
KM1H
----- Original Message -----
From: "Hal W5GHZ" <w5ghz@yahoo.com>
To: <jerry@tr2.com>; <amps@contesting.com>
Sent: Friday, June 15, 2012 11:43 AM
Subject: Re: [Amps] Squirrely 30L-1
Jerry,
You could try detuning the input coil a bit on 15 meters. Maybe a quarter
turn at most. Be careful not to crack the slug. I have two of those amps and
never had a problem with them.
Hal W5GHZ
________________________________
From: Jerry Kaidor <jerry@tr2.com>
To: amps@contesting.com
Sent: Friday, June 15, 2012 5:00 PM
Subject: [Amps] Squirrely 30L-1
Hello,
Today I tried my L1 up on 15 meters. It worked, but it was noticeably
"squirrely". The "tune" function didn't work quite right ( set the
meter to tune, set the exciter to 20W, tune for dip touching the zero
). It resulted in much less than optimum power. On 20M and below, it
works perfectly.
Since getting back on the air - and moving from a house where I lived
for 16 years - I have been unable to find my 20.5 foot input coax. So
I just used a shorter PL-259 to RCA patchcord that I found in the junk.
W8JI writes that the twenty foot coax was just to get some loss, load
down the input Q, and calm the thing down, because Collins didn't
neutralize. He further states that a 2db pad would do the same thing.
So I have a few Q's:
* Is there any practical way to neutralize the 'L1?
* I really REALLY hate to stick lossy stuff in my receive path. This
degrades the noise figure of the radio. I paid a lot of $$ for a radio
with good NF. What if I bought a little hybrid attenuator and stuck it
inside the L1 after the T/R relay? Even better, stick in one for 15M
and another for 10M? I suppose I could build a box with a relay and a
pad in it - run it off the PTT and even some logic to make it work only on
the high bands.... Silly.
- Jerry Kaidor, KF6VB
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