[ARC5] TM ident for BC-946, please

[D. Platt]

The BC-946 is an extension of the SCR-274-N series of equipment and will 
function in that system. The frequency range is .52 - 1.5 MHz.  The I.F. 
is 239 kHz. The book says its identical in mech. design to the BC-453-B, 
etc.  The addendum mentions a few componenet differences and the coil 
"details" are said to be a bit different.  The addendum has the 
schematic and parts list.  Adaptor FT-310-A comes with the receiver for 
providing external voltages.  The manual is contained as an addendum to 
T.O 12R2-3SCR274-2, as revised 25 JULY 1956. Robert Downs has this manual.

Jeep - K3HVG

On 4/27/2014 5:04 PM, Leslie Smith wrote:
>    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?
>   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    The detector is now a 6H6 and the 12A6 has been replaced by a triode.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  It's not part of the SCR-274N series, and I
>    don't even know the meaning of "ZB".
>
>    This set has seen a good deal of work by some-one with side-cutters.
>    Everything under and over the dyno plate is missing.
>   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  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?
>    What is the advantage of a triode output stage?
>
>    (Also, the (12A6) 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.)
>   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
>    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 fila
>    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.comment 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 I can only restore it to a
>    functional condition.
>    The missing tag-strips may present a problem.  Most stages have a low
>    value decoupling resistor in the plate circuit (a few hundred ohms)
>    with a C by-pass to common.  Has any-one had experience running a set
>    without the decoupling?
>    If I don't replace these (remember the tag-strips are missing!) will
>    the set oscillate at the RF (or I.F.) frequency)?
>
>    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 be made to work work and look even look
>    cosmetically acceptable.
>    I'll have a useful Q5-er when the work is finished and I'll know a LOT
>    more about these sets.
>
>
>    73 de Les Smith
>    vk2bcu at operamail.com
>