[Amps] L-4B Grid RF Choke Specs?

[Jim Thomson]

Date: Wed, 25 Sep 2013 21:00:56 -0700 (PDT)
From: Russ Williams <hrd998cc at yahoo.com>
To: "Amps at contesting.com" <Amps at 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