Amps
[Top] [All Lists]

Re: [Amps] PARALLEL CAPS IN OUTPUT

To: "Carl" <km1h@jeremy.mv.com>, <amps@contesting.com>, "Louis Parascondola" <gudguyham@aol.com>
Subject: Re: [Amps] PARALLEL CAPS IN OUTPUT
From: "Jim Thomson" <jim.thom@telus.net>
Date: Mon, 9 Dec 2013 06:17:35 -0800
List-post: <amps@contesting.com">mailto:amps@contesting.com>
### 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

_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps


_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps


-----
No virus found in this message.
Checked by AVG - www.avg.com
Version: 10.0.1432 / Virus Database: 3658/6399 - Release Date: 12/07/13

_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps

<Prev in Thread] Current Thread [Next in Thread>