[ARC5] ARC5 Digest, Vol 109, Issue 45 those 25L6s in the BC-1206-A

Wed Feb 6 17:23:58 EST 2013

I've always assumed that the parallel audio output tubes were to get
a little more audio. The 28D7 dual beam pentode with 24V on the plate
manages 80mW output. Push-pull would mean quite a lot more
hardware, not practical in the small space of a beacon RX.

73, ian K3IMW

On Wed, Feb 6, 2013 at 8:52 AM, Paddy Ryan <pei7cn at eircom.net> wrote:

> There is a 6SS7 in something here ,probably a heavily 'improved' ARC-5
> receiver but I am interested in the reference to those two 25L6s in the
> 1206-A..at first glance I assumed that 2 AF tubes meant push pull but not
> so..why 2 25L6s in parralel? what is the purpose of the two? is it just to
> keep the audio operating in the event of one failing? I have not seen this
> before? ..73 de Pat/EI7CN
>
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> Subject: ARC5 Digest, Vol 109, Issue 45
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> Today's Topics:
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>   1. Re: 6SS7 (Ian Wilson)
>   2. 6SS7 (Robert  Eleazer)
>   3. Re: 6SS7 (john rose)
>
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> ------------------------------**------------------------------**----------
>
> Message: 1
> Date: Wed, 6 Feb 2013 07:43:11 -0800
> From: Ian Wilson <ianmwilson73 at gmail.com>
> To: wrcromwell at gmail.com
> Cc: arc5 at mailman.qth.net
> Subject: Re: [ARC5] 6SS7
> Message-ID:
> <CAEz8jcSUUuFWTu0JJb+**g57MwyYr0mAgH6e9mLbp7FS2QLO6cn**Q at mail.gmail.com<CAEz8jcSUUuFWTu0JJb%2Bg57MwyYr0mAgH6e9mLbp7FS2QLO6cnQ at mail.gmail.com>
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> Content-Type: text/plain; charset=ISO-8859-1
>
> Good catch, Bill. I would never have suspected a 0.15A heater.
>
> 73, ian K3IMW
>
> On Wed, Feb 6, 2013 at 6:54 AM, Bill Cromwell <wrcromwell at gmail.com>
> wrote:
>
>
>> I have a radio or two around here somewhere with *SS7 tubes where the
>> *SK7 once lived. Heater requirements are different so don't stuff into a
>> series string where 6SK7 lived. Plate dissipation is somewhat lower,
>> too. For an IF amp that is probably not an issue.
>>
>> 73,
>>
>> Bill  KU8H
>>
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> ------------------------------
>
> Message: 2
> Date: Wed, 6 Feb 2013 10:56:49 -0500
> From: "Robert  Eleazer" <releazer at earthlink.net>
> To: <arc5 at mailman.qth.net>
> Subject: [ARC5] 6SS7
> Message-ID: <**85636E98DDEF4D3BAF8F74F95DE5D0**F5 at DH26DQ31>
> Content-Type: text/plain; charset="iso-8859-1"
>
> "I have a radio or two around here somewhere with *SS7 tubes where the
> *SK7 once lived. Heater requirements are different so don't stuff into a
> series string where 6SK7 lived. Plate dissipation is somewhat lower,
> too. For an IF amp that is probably not an issue. 73, Bill  KU8H"
>
> That's the really funny thing.  The 6SS7 has half the filament current of
> a 6SK7, and the set uses a mix of series and parallel filament circuits.
>  So it makes a difference which one you use.
>
> It appears the early Detrola 438's use two 6V6's in the audio output -
> with some big resistors back there.  The slightly later BC-1206-A military
> versions use a 28D7, and the later BC-1206-B uses two 25L6's.
>
> Makes me wonder if the 438 originally was designed for 12VDC for civilian
> applications.  I wonder if that would work.  I have run my ARC R-511 on
> 28VDC on both B+ and filaments, but have not heard of sets going lower than
> that.
>
> Other than the audio section the rest of the tubes seem to be the same
> except for the anomalous 6SS7.
>
> By the way, in case you ever wondered, 6V6's get Real Bright when you plug
> them into a circuit designed for 25L6's...
>
> Wayne
>
>
>
>
> ------------------------------
>
> Message: 3
> Date: Wed, 6 Feb 2013 08:13:47 -0800
> From: john rose <brokenthumb at live.com>
> To: arc5 mail list <arc5 at mailman.qth.net>
> Subject: Re: [ARC5] 6SS7
> Message-ID: <BAY167-**W14043FFA5FF2881429DB8A6DA070@**phx.gbl>
> Content-Type: text/plain; charset="iso-8859-1"
>
>
> The HQ129x I had many years ago had 2 (I think) in the IF. The 'Stanley
> Stanley' has more gain than the 'Stanley Kilo' along with less noise and
> about half the heater current. If all the tube heaters are in parallel,
> they are essentially interchangeable.
>
>> From: releazer at earthlink.net
>> To: arc5 at mailman.qth.net
>> Date: Wed, 6 Feb 2013 09:20:54 -0500
>> Subject: [ARC5] 6SS7
>>
>> I have been investigating my collection of five Detrola 438 receivers,
>> sometimes known as the BC-1206.  I have found I have three separate
>> varieties, and more on that later.
>>
>> But in the only set that works I have found a tube I have never seen or
>> heard of before, a 6SS7.  I thought at first it was a bad label, despite
>> that the marking is quite clear, but I can also seen the tube type embossed
>> in the metal, so that is indeed what it is.  It appears that the other sets
>> have a 6SK7 (2) in that spot, or else an unknown glass Ken Rad tube (2).
>>
>> Anyone ever hear of a 6SS7?
>>
>> Thanks,
>>
>> Wayne
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