On 11/12/2010 9:49 PM, Carl wrote:
> Is the D7 amp the same one that was in a few years ago and got pulled
> when the tube was NLA? Now that its available again, at $1200, what
> is the purpose except as a showcase for the author?
If I follow all of it, the D7 is quite different than the 8877. It uses
the same socket as the 3-500Z, has a 5V Thoriated Tungsten filament at
30 A. Same voltage and current as a pair of 3-500Zs and was designed to
replace a pair of them. Except for price I'd pick one over the 8877.
70 watts of drive gives about 2 KW out with 930 watts of plate
dissipation. Oh! The grid dissipation is 50 watts. 3rd order are -29
and -34 dB at 3 and 4.5 KV respectively 5th order are -43 and -37
respectively.
OTOH "Typical operation" under 30 MHz is 5 kVdc on the plate, 0.710 A
anode current, where 95 watts of drive gives 2400 watts out with 1220
Watts dissipation at 3760 Ohms load impedance.
However the max ratings are for 100 MHz unlike the 8877 which will
easily go to 2-meters IIRC.
CPI has the data sheets in pdf.
73
Roger (K8RI)
>
> Carl
> KM1H
>
>
> ----- Original Message ----- From: "Roger (sub1)"
> <sub1@rogerhalstead.com>
> To: <amps@contesting.com>
> Sent: Friday, November 12, 2010 9:40 PM
> Subject: Re: [Amps] 2010 ARRL Handbook
>
>
>> On 11/12/2010 7:52 PM, Hsu wrote:
>>> What new article about RF amplifier in handbook 2011?
>>>
>> They go through the design of an 8877 HF amp, have a construction
>> article on the 3CX1500D7 HF amp (uses vacuum variables for tune and
>> load), and IIRC the 4CX1600B 6-meter amp is the same as in the previous
>> Handbook.
>>
>> 73
>>
>> Roger (K8RI).
>>
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>
>
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