[Boatanchors] 1625 tube(s)

[J. Forster]

I think they are still making 807s, so use those. The supply of 1625s for
use in ARC-5s, etc. is limited and diminishing.

YMMV,

-John

===============


> 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
>>>
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