[Central-Electronics] 10A

[Robert Nickels]

Wonder if there are any 10A gurus on the list?

Been trying to track down what seems to be an intermittent problem with 
low power output, down to only about 2 watts, although at times I've 
seen upwards of 5-6 out, which is what I'd expect.   Substituting 
another 9.0 mhz crystal seems to bring the power back up, so I'm looking 
at the 12BH7 master oscillator.   CE changed the design of this 
oscillator in the 20A so I wonder if it may have been problematic.

The schematic says there should be 50V of RF on the plate, yet I can't 
measure any because a scope or VTVM probe kills the oscillator 
(regardless of L2 adjustment).    I get decent sounding SSB even when 
the power is down, so I think the problem is related to insufficient 
drive, and the 9 mhz oscillator could account for that.  I've used a 
dual channel scope to adjust the 90 degree phase difference, and it can 
be brought right on the nose, so I'm thinking the coils L1 and L2 are 
fine, and it's the simple old triode crystal oscillator that was used in 
many similar rigs.   The original crystal oscillates just fine,  but 
maybe just isn't as active?

Such a cool little simple transmitter!  Thanks in advance for any 
suggestions.

73, Bob W9RAN