### I give up carl. Use strap/wire, or whatever the heck u want. If u
do use strap,
what will work is .75 inch wide cu strap...and space it exactly .3125 inch
above the chassis,
then its 50 ohms. RG-393 teflon coax works good too.
## Place 10- 12 ga wire a couple of inchs above the chassis , and u will
end up with the eq of 250-500 ohms.
This creates too may problems imo.....esp on QRO amps like the 5-15 kw
variety. Depending on total length,
the uh of the wire will make the 10M Pi net now appear like a PI-L. If
you already have a PI-L... it will make it
worse. I have to worry about the peak V /current on both the tune + load
caps, + tank coils and bandswitchs..
and also the vac relays on the output. Plus bypass swr on the upper
bands. Plus toss in high swrs.
## IMO, its just a lot easier to make it 50 ohms from load cap to tr relay
with coax... or flat strap, done right.
Ditto if a PI-L is used. I have seem one too many load caps flash over.
Also seen em run way too hot on the upper bands.
Jim VE7RF
-----Original Message-----
From: Carl
Sent: Saturday, December 07, 2013 7:36 AM
To: jim.thom@telus.net ; amps@contesting.com ; Louis Parascondola
Subject: Re: [Amps] PARALLEL CAPS IN OUTPUT
I havent even seen a theory espoused yet, just some ramblings.
----- Original Message -----
From: "Louis Parascondola" <gudguyham@aol.com>
To: <jim.thom@telus.net>; <amps@contesting.com>
Sent: Saturday, December 07, 2013 8:46 AM
Subject: Re: [Amps] PARALLEL CAPS IN OUTPUT
Jim, if you know this to be true why do you call it a theory? Just
wondering.
### heres one way to test my theory. Toss the load cap..and replace it
with a
50 ohm resistor....
then wire from top of resistor with strap, wire etc, over to a coax
connector......then on to the
MFJ-259B. Now see if the MFJ says 1:1 swr.
-----Original Message-----
From: Jim Thomson <jim.thom@telus.net>
To: amps <amps@contesting.com>
Sent: Sat, Dec 7, 2013 8:22 am
Subject: [Amps] PARALLEL CAPS IN OUTPUT
From: "Carl" <km1h@jeremy.mv.com>
To: "Jim Thomson" <jim.thom@telus.net>, <amps@contesting.com>
Subject: Re: [Amps] PARALLEL CAPS IN OUTPUT
With all your bluster you still dont get it. All you are using is a short
piece of shielded cable, impedance has no bearing since it is too short to
present a meaningful reactance.
Your load cap change is due to the added C to ground of that shielded
cable.
Having it is beneficial if the cable is long or passes near other
circuitry
such as the input. Lift the RG-8 shield on a SB-220 and see what happens.
A high percentage of the ones I get thru here have cold solder joints
which
will do wonders for stability.
Carl
### heres one way to test my theory. Toss the load cap..and replace it
with a
50 ohm resistor....
then wire from top of resistor with strap, wire etc, over to a coax
connector......then on to the
MFJ-259B. Now see if the MFJ says 1:1 swr.
Jim VE7RF
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