SB-200???
Paul Kraemer
elespe at LISCO.COM
Wed Aug 19 22:39:50 EDT 2009
Working on a SB-200 for a friend (really)
I only have the download copy of the manual and note the following
discrepencies:
The grid resistors are 22 ohm 1w instead of 33 ohm 1 watt. One of them
appears original, one was changed
The grid choke rfc2 looks "funny" to me. Too new and a 3 pi style. Measures
2.5milli henry not 28 micro henry
There is no 33 ohm 1 watt in the antenna relay line and doesn't appear there
ever was
There are a new matched pair RF Parts 572-B installed but I am taking this
carefully repairing the obvious first, like the HV meter resistor already
replaced once before and open alc bias resistor. The filter caps all esr
test perfectly ---surprise---but I'll be cautious with a variac first and no
tubes.
Questions:
Was there a early or late version for the 22 ohm 33 ohm grid resistor?
Is the bias provided by the 33 ohm in the relay coil circuit beneficial?
Is the choke in the grid bias critical? If it is then I am looking for a 28
micro henry rfc
Thanks in advance for your helpful suggestions
Paul K0UYA
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