DCR of primaries and secondaries of Hammond Transformer

[cbutterworth]

It's a long story. My Aikido has a very small amount of hum. It is really only audible when the house is dead quiet and there is no music playing. The hum is so low, that I find it difficult to tell if it is 60Hz or 120Hz.

Bruce Anderson has recommended adding a low DCR choke to make a "flywheel PSU", but I do not have the space (I measured it Bruce) unless I build a new chassis.

Anyway, I happen to have a spare 5V4GA rectifier tube. My Aikido uses SS recitification and is delayed with an Amperite 10S delay tube, which allows the 6SN7 filaments to pre-heat. This means that I have an octal socket already on my Aikido chassis.

At present, I am running the Aikido using:

Hammond 269AX (125-0-125) into snubber caps; 1N4007 bridge; 0.68 cap; 10H choke; 60uF cap; 10H choke; 60uF cap.

So, I am thinking that I can replace (with a bit of re-wiring) the Amperite delay with the 5V4GA, which is indirectly heated and will come up to power after around 10 seconds.

I want to model a suitable PSU using PSUD, especially in order to get the correct voltage for the power transformer as I'll replace the Hammond 269AX with one of the 300 series.

However, JoshK reckons that without having DCR's for the primary and secondary windings of the transformer, PSUD can give some erroneous results.

My QUESTION is:

How do I get/calculate the DCR of a transformer that I do not yet own?

Regards,
Charlie

 

[Tweeker]

Without more data than Hammond provides on their website for that line, you cant.

That said, PSU modifications may not necessarily help the hum.