[Amps] Safety choke question

[Carel, pc5m]

Hi Jim,

I suppose you would like to put that choke across the (50Ohm) output
terminal ? Think 225uH is not needed at all to have negligible effect at
160mtrs. I would go for a reasonable sized toroid (2 inch dia) and larger
dia wire. Than you know for sure something else will fail before you
"safety" is no longer in place....

Gl, Carel, pc5m

-----Original Message-----
From: amps-bounces at contesting.com [mailto:amps-bounces at contesting.com] On
Behalf Of Jim Barber
Sent: maandag 9 januari 2012 11:21
To: amps at contesting.com
Subject: [Amps] Safety choke question

So what do you all think about using an RF Parts RFC-3 (225 uh 1.5A 4KV)
plate choke as the safety choke for a large HF amp? 

The supply is 4KV at up to 2A, bridge rectifier with 32uf of filter.
Although the supply *can* source 2A CCS, the duty processor will drop the
mains relays if more than 1A flows for more than roughly 100us. Whether that
happens as designed or the mains fuses blow first I don't know yet.

Anyway - the circulating current in the choke should be low enough to ignore
on 160m, and the effect on the tank should be manageable, especially since
this amp won't run above 20m. (in this incarnation at least) I *think* the
wire should be large enough to hold until the mains fall out and the caps
discharge, but I'll have to think up a way to test that without stressing
the supply or myself too much.

I got the idea from an old posting of Ian's, in case anyone experiences deja
vu... ;-)

Thanks and 73, 
Jim, N7CXI

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