[AMPS] Caveats for factory-stock TL-922 owners

[measures]

If a tube shorts, it could summarily melt down the unfused filament 
transformer during standby.  The fix is to cut the wire that applies 
+110vdc to the bias contacts of the small relay.  

 The stock Tune-C has a breakdown potential of c. 6100v.  To protect the 
bandswitch  from parasite-related arcing, bend the first rotor plate on 
the Tune-C to uniformly reduce the clearance from the first stator to 
about 2/3 of normal.  After bending the first rotor plate, the measured 
breekdown potential should be a bit under 4000v --  about 1000v less than 
the withstanding ability of the bandswitch.  Thus, the bandswitch is 
automatically protected from arcing by the Tune-C.  .  

3A diodes should be placed across the Plate meter movement.  (the grid 
meter is already protected).  

The 922 needs at least one, 10-ohm, 10w WW  resistor in series with the 
B+  to provide protection against bending filament helices during 
parasites.  

For operation on 160m, the HV bypass C needs to be increased by >2x.  

To prevent hot switching with modern radios, faster T/R relays are 
needed.  See my Web site for a diagram and discussion.  

good luck



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


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