An 8877 needs more voltage than a 3CX800 for one. The socket is different
also. Plus it is a lot larger if space is an issue.
-----Original Message-----
From: john nistico <electric911inc@hotmail.com>
To: Peter Voelpel <dj7ww@t-online.de>
Cc: towertalk <towertalk@contesting.com>; Herbert Schoenbohm
<herbert.schoenbohm@gmail.com>
Sent: Sun, Feb 12, 2017 9:12 am
Subject: Re: [TowerTalk] 3CX800A7 vs. GU-74B
Can you replace 3cx800 with 8877?
Sent from my iPhone
> On Feb 11, 2017, at 8:34 PM, Peter Voelpel <dj7ww@t-online.de> wrote:
>
> An EIMAC tetrode 4CX800A was never fabricated.
>
> 73
> Peter, DJ7WW
>
> -----Original Message-----
> From: TowerTalk [mailto:towertalk-bounces@contesting.com] On Behalf Of
> Herbert Schoenbohm
> Sent: Samstag, 11. Februar 2017 21:35
> To: towertalk@contesting.com
> Subject: Re: [TowerTalk] 3CX800A7 vs. GU-74B
>
> Thanks to all that responded to my inquiry about using the GU-74B's (a
> tetrode) in triode socket configuration as a replacement for the
> increasingly expensive and affordable 3CX800A7's. All agree it could
> not be done or should not be done especially in the case of Alpha 87A
> which has a very extensive firmware protocol. Now here comes the good
> news, at least for some of you....Many recently newly manufactured QRO
> amps are using the GU-74B's (tetrode) and they are still going at a
> reasonable price. In fact there are 10 of them on eBay today for a
> reduced price of $195.00 each from one vendor.
>
>
> Herb Schoenbohm, KV4FZ
>
>
>> On 2/5/2017 6:09 PM, Herbert Schoenbohm wrote:
>> I have been trying to buy just one single triode 3CX800A7 to fix a
>> problem with a sick Alpha 87A. Several match pair are available but
>> used and will only be sold in pairs. The new Eimac version of this
>> tube are still available but cost as much as the amplifier did years
>> ago! The less expensive Machlette (Chinese) version of this tube,
>> although advertised on eBay, are reportedly not in stock and a 60-90
>> day waiting period. However, Svetlana (Russian Federation) made many
>> thousands of the GU-74B which is there version of the Eimac tetrode
>> 4CX800A. The GU-74B's are plentiful on eBay for a third the price of
>> a 3CX800A7. I have successfully before used spare tetrodes (4-400's)
>> as substitutes for 3-500Z's in several amplifiers by merely making
>> sure the screen grid was connected to the grounded grid at the
>> socket. My question is if the GU-74B's could be successfully operated
>> as a triode. I have not found a print of the socket for the GU-74B
>> and if there is a difference requiring a socket change this idea would
>> be a non-starter. Many EU hams are using the GU-74B in home built
>> amps and now more and more commercial amps have chosen them as their
>> PA tubes. Please let me know if the idea of using a GU-74B is even
>> feasible. A single 3CXP800A7 (medical version used in MRI's) if good,
>> would also solve my problem if I could only find a source.
>>
>> Thanks,
>>
>> Herb Schoenbohm, KV4FZ
>>
>
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