[Amps] Size of Parasitic Chokes

[Dave White]

My current 3CX3000 amp has no parasitic suppressor at all.  I originally built one using a coil and a large 50 ohm carbon resistor but found low efficiency.

I spoke to Reid Brandon W6MTF at Eimac and he advised me to simply take it out and not wory about parasitic suppression.

I have had no problems whatsoever.  However I was totally neurotic about isolating the plate compartment from the cathode area.  Everything is either screened or runs via feedthru capacitors and the base and top panels are rf-sealed with finger stock. 

The tubes I got (Dayton fleamarket if I recall correctly) were 3CX3000F7s though I removed the filament leads with a blowtorch (carefully!) so they'd fit an RF Parts coaxial socket.  The grid is earther directly to the chassis via a finger stock grid ring.

Hope this helps
Dave G0OIL

-----Original Message-----
From: "Mike Saculla" <fqm at msn.com>
To: "amps at contesting" <amps at contesting.com>
Sent: 16/07/2010 05:07
Subject: Re: [Amps] Size of Parasitic Chokes


I see 3CX3000A7 amps with no suppressor at all. How stable have any of you found this tube to be? Anyone have one take off on them with no suppressor? Or should I include one just to be safe?

Mike K6MDS


--Forwarded Message Attachment--
From: km1h at jeremy.mv.com
To: sub1 at rogerhalstead.com; Amps at contesting.com
Date: Thu, 15 Jul 2010 20:53:59 -0400
Subject: Re: [Amps] Size of Parasitic Chokes

The YC-156 doesnt use a socket and hasnt shown any need for a suppressor.

[truncated by sender]