[Hammarlund] Old Hammarlunds - modifications.

[Carl]

Changing the RF amps to 6SG7's and the mixer to a 6SB7Y would be 
conservative and quickly reversible. Nothing less would overcome the stock 
noise on 10M to a significant degree. Use the SP-600, NC-183D and HRO-60 as 
examples. They all use 6BA6-6BA6-6BE6 line ups but going with 6GM6-6BA6-6BY6 
makes a very noticable improvement with only minimal changes for the 6GM6. 
Anything works at 10-12mc and below, even early 30's sets.

Changing the mixer to a 6SL7 Pullen is more involved but also reversible.  I 
wonder how a 6SN7 would work as an oscillator buffer?

Carl
KM1H