[Amps] SB200 Anti Parasitic Chokes

[Paul Baldock]

A few weeks ago I posted asking if anyone new the optimum 
Anti-parasitic chokes (APCs) to use when modifying an SB200 for 6 
Meters. I received some interesting comments but no definitive 
answer. So I thought I would share with you what I came up.

I experiment with many different combination or R and L and came up 
with something very similar to the original used in the SB200. The 
original SB200 APC is a 47Ohm/2W Carbon Comp in parallel with about 
.08uH. This actually works well a 6M except the resistor get quite 
hot. In fact I disassembled the original APCs and found the resistors 
actually measured around 65Ohms probably due to age and heat stress. 
Based on the higher value working well I finished up with 2 x 
150Ohm/3W low inductance metal film resistors in parallel with .08uH. 
I tried 3 in parallel and it did not make any difference so I went 
back to 2. These run only slightly warm

If anybody wants any info on doing the SB200 6M conversion feel free 
to contact me directly. No secrets here!

BTW I did remove the chokes and caps between the Grids and Ground on 
the 572Bs and replaced them with a direct short to ground resulting 
in more output power and less drive required. No flames about this please.

- Paul  KW7Y