[Amps] Chinese 4CX1000A from Alpha

[Vic, K2VCO]

I didn't intend to criticize Alpha. Alpha said they were 
"interchangeable in these amplifiers" which is reasonable if they are 
running lower screen voltage. Since they are using two tubes, the lower 
efficiency and output from the 4CX1500B is not a problem. I just wanted 
to note that they are different in more than plate dissipation.

On 11/16/13 1:01 AM, Roger (K8RI) wrote:
> On 11/15/2013 7:27 PM, Vic K2VCO wrote:
>> According to the data sheets, they are very different. The 1500B has a
>> special grid structure that produces a very low level of IMD, if you
>> operate them according to the parameters on the data sheet -- which
>> includes a screen voltage of 225 instead of the 325 spec'd for the
>> 1000A.
>
> Doesn't the Alpha run the lower screen voltage?
> If it does there shouldn't be a problem.
> In past amps, I've used the interchangeably although I never measured
> IM, I never had a bad report.  OTOH that was quite a while ago.
>
> 73
>
> Roger (K8RI)
>
> The efficiency is low compared to the 1000A as it is spec'd.
>> Maximum output from the 1500B at 3kV is less than 1500w per tube, even
>> with the greater plate dissipation.
>>
>> When I started my amp project I had some 1500B pulls that I thought
>> about using, but since I wanted to use a single tube, and since I work
>> almost entirely CW, I figured the 1000A was more appropriate.
> <snip>
>
>
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-- 
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco/