Date: Wed, 25 Sep 2013 21:00:56 -0700 (PDT)
From: Russ Williams <hrd998cc@yahoo.com>
To: "Amps@contesting.com" <Amps@contesting.com>
Subject: [Amps] L-4B Grid RF Choke Specs?
Does anyone have the specs for RFC-1 and RFC-3 in the Drake L-4B?? These are
the RFC's that ground the grids of the tubes.? They look to be between 1 and
3mh but appear to be higher current rated than your garden variety chokes
usually found.? I assume I can source them at Mouser et. al?
Thanks.
Russ
KW6T
## I removed those chokes from my 4 x drake L4B amps that I own. They all
measure just .91 ohm each. Which is a helluva lot less than the 25 ohms on a
SB-220 grid choke.
I believe the drake chokes are aprx 1.5 to 2.5 mh. I will dig them out
later on tonight..and measure them again..with my B+K 875B digital lcr meter.
## I know for a fact the dc resistance was .91 ohm on all 8 x chokes..... but
Im not sure of the exact Mh value of each choke. Nor what the CCS current is
rated at, but I believe its fairly high.
They are a superb choke...... but I sure as heck wouldn’t be using em in a GG
tube amp. Toss the choke and the 3 x caps on each tube socket. Instead
bond each of the 6 grid pins
directly to the chassis with wide cu strap. Then your drive power
requirements will drop by 20-25 watts. Then your xcvr will run cleaner
too, since its imd will be better when run at
20-25 watts less.
later.... Jim VE7RF
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