[AMPS] SB-1000

[measures]

>
>Ford Peterson wrote:
>> 
>> I bought an SB-1000 from an estate that looks to be unmodified in any way.
>> Are there mods out there that I should investigate?  Any on-line resources I
>> should look at?
>
>The stock plate RF choke may have a resonance near 17 meters.  I replaced the
>one in mine with an Ameritron AL80B choke, which works well on all bands,
>including WARC.  Cost about $25 from Ameritron.
>
>There is a very high potential gradient at the fixed bandswitch contact that
>grounds the 160-meter padder capacitor.  This can actually cause a corona
>discharge from sharp points on the contact and the wire connected to it.  

€  To see what's  happening, loosely couple a spectrum analyzer to the 
anode.  SB-1000/AL-80s are  marginally stable.  They tend to oscillate 
intermittently at 155MHz.  Lower VHF Q suppressors are needed to reduce 
parasitic arcing.  See my website for photos of burned bandswtiches.  .  


later, Vic

-  Rich..., 805.386.3734, www.vcnet.com/measures.  
end


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