[AMPS] UrgentSwedish questions

[measures]

>
>
>Questions to those who know:
>
>Is there anybody who has experience of inserting new SVETLANA 572Bs in a
>HEATH SB200? Any risk for parasitics that the original tubes did not have?
>
>Another question: I am just repairing for a friend a HEATH SB1000 and on 160
>the  switch contacts  that connects the C26 270 pF doorknob are both burned.
>It seems that the switch could not take the current through this condenser?

The existing current burden is not a problem.  When the amplifier 
intermittently oscillates at c. 155MHz during operation on other bands, 
the (open) 160m Tune-C padder switch tends to arc.  A photo of a 
bandswitch with a similar problem on the 80m Tune-C padder contacts is 
shown on my Website.  See Figure 23 -  Burned ... ... ... .  

>Is this a often found problem in this amplifier? 

Not as common as bandswitch trouble in a TL-922.  

>Where do I find a new switch ? 

Ameritron/MFJ, AL-80 bandswitch is ok.  

> I am planning to let the new switch contacts actuate a small high
>frequency relay that handles this hf current??
>
no help  Lowering the  Q of the vhf suppressors might help.  

>The toroid on 160 is red not yellow, by the way. Any comments?
>
Red is ok up to 30MHz.  

cheers,  Hans


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


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