[Boatanchors] 1625 tube(s)

[Bob Macklin]

807s have 6V filaments. 1625s have 12V filaments,

Good 807 sockets are easy to find. I don't know about 1625 sockets.

Bob Macklin
K5MYJ
Seattle, Wa.
"Real Radios Glow In The Dark"
----- Original Message ----- 
From: "Pete Lancashire" <pete at petelancashire.com>
To: "Richard Knoppow" <1oldlens1 at ix.netcom.com>
Cc: "Boatanchors Mail List" <boatanchors at mailman.qth.net>
Sent: Wednesday, March 23, 2011 12:31 PM
Subject: Re: [Boatanchors] 1625 tube(s)


>a side question. If one was building a 40 M xmitter from scratch for
> fun would one want to use a 807 or a 1625 ?
> 
> any reason one over the other .. I can't think of any.
> 
> -pete
> 
> On Wed, Mar 23, 2011 at 11:36 AM, Richard Knoppow
> <1oldlens1 at ix.netcom.com> wrote:
>>
>> ----- Original Message -----
>> From: "rbethman" <rbethman at comcast.net>
>> To: "Boatanchors Mail List" <boatanchors at mailman.qth.net>
>> Sent: Wednesday, March 23, 2011 9:34 AM
>> Subject: [Boatanchors] 1625 tube(s)
>>
>>
>>> I've had to go back as far as a copy of the 1941 Radio
>>> Handbook
>>> published by the ARRL to find a "proper" tube diagram that
>>> clearly shows
>>> the "beam forming plates". However, this stopped at
>>> listing of the
>>> 1621, (not its diagram.), and it did not list the 1625.
>>>
>>> This simply leaves myself and others in the *elifIknow*
>>> mode!
>>>
>>> Then again, I have no intent of using 1625s in GG. I
>>> don't have a thing
>>> here that even uses them. I *DO* have equipment that uses
>>> 807s. That
>>> would be the BC-610 and the T-213.
>>>
>>> So we have beat it to death, and find the tube manuals
>>> "LACKING"!
>>>
>>> Bob - N0DGN
>>
>> FWIW, the RCA receiving tube handbooks all have a
>> section describing beam power tubes with a drawing and
>> explanation. I am not sure when the standard tube diagrams
>> stopped indicating the plates and replaced them with the
>> pentode symbol. I thin it was a simplfication of required
>> symbols.
>> The beam forming plates act in some ways like a virtual
>> suppressor grid since the field they produce eliminates
>> secondary emission and the negative resistance
>> characteristic found in tetrodes. I am not certain what sort
>> of characteristics the plates have as far as being able to
>> modulate the electron beam. It may be they have enough
>> effect to function as a modulation grid or perhaps not. Beam
>> pentodes seem to have originated around 1935. They have
>> better efficiency than power tubes employing a third grid
>> such as the 6F6. The 1625 and 807 are very similar in
>> construction to the 6L6 but have plate caps which lowers the
>> interelectrod capacitance and extends the maximum frequency
>> considerably.
>>
>>
>> --
>> Richard Knoppow
>> Los Angeles
>> WB6KBL
>> dickburk at ix.netcom.com
>>
>> ______________________________________________________________
>> Boatanchors mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/boatanchors
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:Boatanchors at mailman.qth.net
>>
>> List Administrator: Duane Fischer, W8DBF
>> ** For Assistance: dfischer at usol.com **
>>
>>
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html
>>
> ______________________________________________________________
> Boatanchors mailing list
> Home: http://mailman.qth.net/mailman/listinfo/boatanchors
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Boatanchors at mailman.qth.net
> 
> List Administrator: Duane Fischer, W8DBF
> ** For Assistance: dfischer at usol.com ** 
> 
> 
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html