[Boatanchors] 1625 tube(s)

[Greg Mijal]

I would go with the 807 for a couple of reasons:
6 v filamant vs 12 v for the 1625 - most of the power transformers out there 
have 6 v windings so the candidate transformer selection pool is much 
bigger.
Cheapie 1625's at the flea market are typically gassy or weak.  I'm from 
Arizona so out there the glue dries out on the  old 1625 and kills the plate 
cap assembly and causes the glass to twist around in the base.  If you buy 
10 of them out of a pile, 2 good ones is about all she wrote.
East coast 1625's seem to be in better shape.  Most likely the glue hasn't 
been burned away by dry, hot weather.
Last but not least, good useable 807 sockets are much easier to come by then 
the 1625 socket.
I bought 4x1625's for an Collins ARC-2 re-tube job.  Paid $3 a piece for NOS 
in the military box.  Very good batch of 1625's.
807 = secret ham code word for beer
1625 - secret ham code for non-alcholic beer (no boom!)
Anyone know the secret code word for Malt Liquor?
73's & have fun with the project
Greg
WA7LYO
Kinston NC
----- 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 3:31 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