Thread: Taylor 61A
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Old 17th Aug 2012, 11:54 am   #11
WME_bill
Octode
 
Join Date: Oct 2007
Location: Exeter, Devon, UK.
Posts: 1,553
Default Re: Taylor 61A

Taylor 61A AM/FM signal generator.
May I suggest that it is simpler than you think. The reactor sweep coils (L1,L2) appear to require about 12V rms/30V pk through the phase shift network C47/VR6. So use two 6.3v windings in series and split the valve heater load between the windings. So almost any small transformer giving 200-250V/50ma and 6.3v 2a should be enough for the valves etc, and another 6.3 transformer in series to drive the Sweep. Even a 8 to12V bell transformer could be used. The sweep voltage is not particularly critical, current maybe 0.5A. These small valve transformers were available at one time for TV pre-amps, but seem to have disappeared.
I am estimating the voltages and the current loads from the details given in the manual, but can measure it on my model if you would like that done.
The feed to V1B grid is for the sweep blanking, an ingenious arrangement described in the manual. V1A is the FM/Sweep oscillator, and V2B the AM oscillator.
Interesting is the use of ECC85, which is effectively the equivalent of the ECC81/12AT7 with internal screen, as the AM/Xtal oscillators. This is done presumably as the internal screen reduces interaction between the Crystal marker section V2A and the AM/Marker oscillator V2B. I will experiment sometime on using the ECC81/12AT7 instead.
I see you have the manual, else PM for a copy by email. It comes to 4.8M. wme_bill m0wpn
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