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

[Richard Knoppow]

     I think I have these phones with my BC221 AK and will measure them. 
I suspect the impedance given is for a single phone, usually they are in 
pairs connected in series. My phones were made by Murdoch but I am sure 
other companies built similar ones under contract.
     My BC-221 still works like a charm.

On 1/5/2018 6:29 AM, J Mcvey via ARC5 wrote:
> Just happened upon a passage in the manual that says 'later models used 
> the HS-30 headset". I looked up the HS-30 and it's 256 ohms.
> Like I said, they were in transition mode mode...
> 
> So, the primary should be about 8000 ohm s and the secondary should be 
> 256 (300?) ohms.
> If you find the turns ratio, it should fit this profile.
> 
> 
> On Friday, January 5, 2018 9:17 AM, J Mcvey via ARC5 
> <arc5 at mailman.qth.net> wrote:
> 
> 
> 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.
> 
> Hope this helps...
> 
> 
> On Friday, January 5, 2018 5:16 AM, Leslie Smith <vk2bcu at operamail.com> 
> wrote:
> 
> 
> The subject line is the point of this posting.
> 
> More info:  (1) This transformer is shown as item 17 in the circuit 
> diagram for the "AK".
> The manual describes this as "output transformer".
> I find no other information in the BC-221 manual.
> In particular I wish to know the impedance of the primary & secondary 
> windings.
> 
> Thanks to all,
> 
>    73 de Les Smith
> vk2bcu at operamail.com <mailto:vk2bcu at operamail.com>
>
-- 
Richard Knoppow
1oldlens1 at ix.netcom.com
WB6KBL