[ARC5] Info sought about output transformer in BC-221-AK

[WA5CAB at cs.com]

If you look through the BC-221 accessories supplied lists from BC-221-A 
through BC-221-AN, you will find that the headsets supplied are all either 8000 
ohm or higher, or on the later ones HS-30 with CD-605.  HS-30 itself is 256 
ohm nominal.  But using it requires installing one of four cords.  Two have 
a straight through junction block JB-47 and two have a step-up transformer 
C-410, which is 256 to 8000 ohms.  CD-605 is the long cord with the C-410 
transformer.  So I would assume that the putput transformer is somewhere 
around 7000 ohms primary and around 7000 to 8000 ohms secondary.

Robert Downs - Houston
wa5cab dot com (Web Store)
MVPA 9480

In a message dated 01/05/2018 08:17:37 AM Central Standard Time, 
arc5 at mailman.qth.net writes: 
> Leslie,
> 
> 
> That was a very crytic entry! They will usually at least provide primary 
> and secondary turns...
> There may be a master "supply list" in that manual with more detail but I 
> don't have time to hunt for it.
> 
> 
> None the less, it can be "reverse engineered" by looking uo the 6sj& tube 
> data. At 100V is shows a class A plate resistance of 8250 ohms, so that 
> would be the primary impedance. The secondary is probably called out in the 
> Bc-221AK specs somewhere. Probably somewhere i the 600 to 3000 ohm area. They 
> were in a headphone impedance transition back then, so different versions 
> can require different headphones. If they don't call out the impedance , 
> you may be able to find the spec for the supplied headset.
> 
> 
> 
> 
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