[ARC5] TM ident for BC-946, please

[Brian Clarke]

Hello Les,

I have a copy of the addendum to the SCR-274-N manual that includes the 
BC-946. I can copy it for you - or I can try to scan and send it digitally - 
except the circuit diagram, unless I reduce it to A4 size. I can also 
probably help you with tag strips.

A mains transformer is not a good substitute for an output transformer - I 
can't recall where I have argued this point in great detail on another list.

What the Americans have absolutely no idea about is that the British A V Roe 
aircraft used by the RAAF was 12 V battery-powered, and so the Aussie 
government had many Command sets modified for Australian use in 12 V powered 
weapons and personnel carriers -not only aircraft, but also APCs, Bren gun 
carriers, Ferrets, Land Rovers ... Sometimes an 'X' was stamped on the 
nomenclature plate to indicate the 12 V modification; sometimes an 'AWA 
Modified [date]' roundel was rivetted to the side.

73 de Brian, VK2GCE.

On Monday, April 28, 2014 7:04 AM, Les said:


>  Good-morning list readers,
>  I have a well-hacked BC-946 I'm seeking to restore to working
>  condition.
>  Can any-one advise the series that the BC-946 belongs to, and/or the
>  TM manual for this series?
>
>  This set has seen a good deal of work by some-one with side-cutters.
>  Everything under and over the dyno plate is missing.
>  The detector is now a 6H6 and the 12A6 has been replaced by a triode.
>  Does any-one remember a "mod" where this was done.
>  (Also, the output transformer is missing.   I'll try a 240 .. 12v
>  filament transformer as a replacement and advise the result.  Will the
>  D.C. in the plate circuit saturate the transformer core?  The world
>  holds it's breath in anticipation of the answer.)
>
>  The filaments in the set are wired in parallel.
>  Has anyone seen an original BC-946 with the filaments wired for 12
>  volts?
>  As an additional point difference all the "tubes" are 6 volts types,
>  so - as I got it - the set is meant to operate from a 6v filament
>  supply.  I suppose that somewhere in the past some-one had a 6 volt
>  filament transformer and decided to use that.
>
>  Most of the circuit in front of the detector seems intact, apart from
>  the fact that two of the four tag-strips are missing.
>  Anyway, this set is so far from original it can only be restored to
>  functional.
>  The top deck and rear panel of the dyno area are cut away, so I'll
>  need to fabricate two Al plates to cover the damage.
>
>  With careful work the set can will work and look cosmetically
>  acceptable.
>
>  73 de Les Smith
>  vk2bcu at operamail.com