[ARC5] BC-453 B dynamotor hum

[J Mcvey]

I found an exact replacement audio output transformer in an "extreme restoration challenge " receiver that was way on the back burner.No joy., the problem still persists. I even replaced the 2 meg grid resistor because it seemed unstable and it read 2.85 meg. 
This makes no sense, so its going to be something really stupid!
 


     On Sunday, November 1, 2015 6:57 PM, Kenneth G. Gordon <kgordon2006 at frontier.com> wrote:
   

 On 1 Nov 2015 at 18:42, WA5CAB--- via ARC5 wrote:

> It would need to be a plate to 70.7 volt line.  Your garden variety 70.7V 
> and 25.? V line transformers are line to voice coil.  A 70.7 volt line 
> happens to be 500/600 ohm line (it's a long story).

Well, yes, but it also depends on the exact type of 70.7 V transformer. Those 
which are labeled or specified for varoius "wattages" output have 
impedances up to something like 5K ohms. I have forgotten the exact values, 
but can dig out the info.

As I remember it, using the .625 watt output as the primary matches the 
output of the 12A6 stage almost exactly.

I'll dig out the definitive info and post it here asap.

In any case, secondaries are 4 and 8 ohm, and in some rarer cases also 16 
ohms.
______________________________________________________________
ARC5 mailing list
Home: http://mailman.qth.net/mailman/listinfo/arc5
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:ARC5 at mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html