[Heath] SB101 Refurbishment

[G3OOU at aol.com]

Hi Ken
 
I have now tracked down the problem with a slow transition to transmit on  
CW which was due to a previous owner changing the Vox timing capacitor C213 
to  1uF instead of the correct value of 0.22uF but using a capacitor almost  
identical mechanically to the correct type. Having replaced the capacitor 
it now  works correctly, the relay driver anode voltage drops from 300V to 
90V in about  10mS and the first dit can be seen in the RF output.
 
During the investigation I noticed that the anode waveform of V17a is  
considerably distorted. This is probably due to reducing the value of R328  from 
470K in order to increase the keyed sidetone signal into the Vox amplifier  
and detector. I will try reversing out that change.
 
73

Bob

Bob F Burns
C Eng,  FIET, MSE
Amateur Radio Callsign: G3OOU
Registered RSGB  Instructor
G-QRP Member No: 6907; Zone: 14, QRA: IO91WH; WAB:  TQ25
Secretary of Crystal Palace Radio & Electronics Club: _www.g3oou.co.uk_ 
(http://www.g3oou.co.uk/) 
Technical web site: _www.qsl.net/g3oou_ (http://www.qsl.net/g3oou) 
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