[MRCA] DAV output transformer

[B. Smith]

   Walk on the wild side,  open er up - maybe it won't be "potted".  
Even if it is potted take a hot air gun and melt the potting material  
to expose leads etc.   A lot of the older WWII transformers and IF coils 
have broken connections to the base pins - - -the leads being weakened 
when soldering during initial construction  when using some exotic flux 
from another planet.

Z

On 3/25/2018 5:49 PM, Ray Fantini wrote:
>
> Ok, so I have a DAV transceiver on the bench that appears to have a 
> failed primary on the audio output transformer. The secondary is good 
> but the primary has gone open. Its in the plate side of a 3S4 and has 
> a +135 volt buss that feeds it. Use to work but now its dead. The big 
> issue is that the transformer is in a sealed metal can (T101A) that 
> also has the modulation reactor and the microphone input transformer.
>
> Anyone have any experience dealing with opening up the can and what’s 
> inside? Options at this time include installing a new transformer 
> somewhere else in the radio, installing a plate load resistor and a 
> decoupling capacitor and using high impedance headphones or perhaps 
> getting rid of the 3S4 completely and building a solid state output 
> amplifier around something like a 741 op amp and using that to drive 
> the headphones?
>
> That transformer can has a flock of wires that go in and out that none 
> are going to be easy to deal with. Wonder if the can may be 
> disassembled on the chassis without having to deal with all the other 
> stuff for the modulator? Another option would be finding the radio 
> section from another DAV or MAB transceiver and moving the crystals 
> and tubes to that. Before anyone says anything I know there are some 
> differences between the MAB and the DAV but converting a MAB to a DAV 
> is just addition of a couple parts right on top the chassis and way 
> easier then this output transformer problem.
>
> Any suggestions welcome.
>
> Ray F/KA3EKH
>
>
>
>
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