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 HeathSB-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
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   
