SB-200 "Conversion"   

I have received several queries on conversion of the SB-200 for operation on
6 meters and thought I'd summarize what I've found.

I know of three published conversion articles.  Listed below is a summary
each.


"Using The Heath SB-200 Linear On Six Meters"
by Henry Blodgett, W2UTH/W2FRL in January 1969 QST.

Operation on HF is maintained - 40 meters is eliminated and the taps are
moved up on the band switch so that a spot for 6 meters is available.  A tap
is added to the 10-15 meter coil for 6 meter operation.  Plates are removed
from the existing tuning cap to allow coverage of 6 meters.  The 40 meter
input coil is re-wound and the associated capacitor is changed.

With 900 watts of input power (Driven by a Heath SB-110) 450 watts output is
obtained.


"Improvements to Using the Heath SB-200 Linear on Six Meters",
by Ron Klimas, WZ1V,  published in the 1995 Eastern VHF/UHF Conference
Proceedings

This article provides Ron's experience with the QST conversion.  Ron states
that he has been using the converted SB-200 on 6 & 75 meters since 1982.

Ron recommends removal of the SWR/Relative Power monitoring circuitry, the
usage of coaxial SPDT relays to replace the original open frame type relays
and the usage of good quality coax in the RF output circuit.  With these
changes a major improvement in RF efficiency is obtained: 600 watts out
instead of 400,  He also recommends new plate parasitic suppressors, beefing
up the cooling and replacing the HV rectifier stack.

I believe both of these articles are available from the ARRL for a nominal
charge.


"Six-Meter Conversion of the Heathkit SB200 Linear Amplifier"
by Louis Savioe, K1RAK  in November 1971 Ham Radio magazine.   

This conversion is more extensive.  It replaces the existing output PI
network with new capacitors and coil and HF operation is no longer possible.
 The plate parasitic suppressors are modified.  The 10 meter input coil is
modified and the associated capacitor is changed. A RG-8/U coax run and  a
Z-50 RF choke are added.
600 watts out for an SB-110 drive power of 60 watts is obtained.

Since HR was bought by CQ you might be able to get a reprint/copy of the
article from them - I haven't checked this out.

  

Conversion Success/Problems

I have yet to hear from anyone who has had extensive problems with the QST
article conversion.  I have heard from several who have instability problems
with the HR article conversion - including me.  My next step is to
incorporate several of  WZ1V's recommendations into the HR conversion to see
if that improves stability! 73 & Good Luck! Bob..... W3RW