[ARC5] TM ident for BC-946 - thank you, all.
Leslie Smith
vk2bcu at operamail.com
Tue Apr 29 13:37:18 EDT 2014
To ARC-5 list-readers,
I posted a request for info about the TM for the BC-946 two days ago.
I got a surprising number of replies - all informative and some more
to the point of my question than I intended when I asked it!
What other list has members that can divine the intent of a question
beyond the words written?
Thank you - all - for the information.
Les
On Mon, Apr 28, 2014, at 7:33, D. Platt wrote:
> 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 The detector is now a 6H6 and the 12A6 has been replaced by a triode.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
> >
>
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