Agree with Dave. In the past I turned out many 1-2 holers grid or cathode
driven to order; most covered 160 or 80-10M. Then I used 20-25W Globars or
surplus 68 Ohm 50W Carborundums which I bought almost 100 in sealed packages
for real cheap.
Stopped that when all the local AM stations used the tubes until they were
even almost dead as modulators or went SS. I did about 10 3CX3000A7's and a
few 4CX5000A's after that.
Carl
KM1H
----- Original Message -----
From: "DAVE WHITE" <mausoptik@btinternet.com>
To: <amps@contesting.com>; "Rob Atkinson" <ranchorobbo@gmail.com>
Sent: Thursday, July 15, 2010 3:34 PM
Subject: Re: [Amps] parasitic suppressor voodoo
On a 2 times 4-1000A amp (5.5kv, grounded grid, cathode driven) I used two
separate parasitic suppressors, each with 3 paralleled 50 ohm carbon
resistors inside a 15mm diamater two-turn coil of 2mm copper wire over about
10mm length. The amp has worked flawlessly (80 thru 10m) for many years.
If yours is a low band amp, you could probably make REALLY certain by
increasing the number of turns on the coil. Initially with four turns the
resistors smoked a little on 10m. I guessed "too much L". There was no
science to building these suppressors - it was a case of looking at the
W6SAI "Radio Handbook" and seeing if it worked. Voodoo? Maybe.
I didn't try the amp without parasitic chokes but it seemed to work and "if
it ain't broke, don't fix it"....
Hope this helps
Dave G0OIL
--- On Thu, 15/7/10, Rob Atkinson <ranchorobbo@gmail.com> wrote:
From: Rob Atkinson <ranchorobbo@gmail.com>
Subject: Re: [Amps] parasitic suppressor voodoo
To: amps@contesting.com
Date: Thursday, 15 July, 2010, 18:40
I would love to know what if any p.s. is needed on a pair 4-1000A at
4.5 KV triode connected cathode driven for 160, 75 and 40 m.
rob
K5UJ
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