>
>I too had an AL1500 Amplifier and was wondering why there was no parasitic
>suppressor of any kind on the plate as mentioned in my previous postings to
>this reflector. ... But no satisfactory response.
There can not be a satisfactory explanation because the designer of the
AL-1500 ignores the 8877's feedback C. Sure, up to a certain point, the
grounded-grid acts as a shield between the anode (output) and the cathode
(input) and prevents oscillation. However, as frequency increases, at
some point, the feedback C will be sufficient to sustain regeneration.
The 8877 apparently has enough feedback C to sustain oscillation above
roughly 100MHz. If there is an AL-1500 owner out there who has a
dipmeter, please measure the anode-resonance in the AL-1500. If it is
over 90MHz, in my opinion, the use of a VHF parasitic suppressor is
indicated.
> Maybe if I shake the
>credibilities of the design engineer(s) I will, hehehe : ) How does one
>get to be an engineer with no training in Physics?.
Delusions of grandeur? Denial of reality? Self confidence does not make
up for insufficient education. The good news is that Mr. Rauch got the
heater circuit right.
>By the way Electricity
>and Electronics is a branch of Physics. As told by my College Physics
>Professor K. Nose (d) KH6IJ in days gone by .
>
Yea, verily, Ed
As I recall, a photo of a kaput tube from one of his 8877 amplifiers
appeared in ''Parasitics Revisited'' (9-1990 *QST*)
>----- Original Message -----
>From: Phil Clements <philk5pc@tyler.net>
>To: measures <2@vc.net>; <N6BUU@aol.com>; <n6er@yahoo.com>; AMPS
><amps@contesting.com>
>Sent: Wednesday, June 21, 2000 2:09 PM
>Subject: Re: [AMPS] RF filament choke for indirectly heated cathodes?
>
>
>>
>>
>>
>> >>> Rich wrote:
>> >>> In other words, put a jumper between the cathode and the heater, and
use a
>> >>>heaterchoke - the same as one would do for >>30MHz operation >>
>> >
>> >> MAKES U WONDER JUST HOW MUCH MORE IT WOULD COST THE MFG. TO DO IT RIGHT!
>> >> HANK
>> >
>> >Ameritron does it right, but alas, no anode parasitic suppressor!
>> >
>> ? ... incredible, Phil. The designer of the AL-1500, Charles Thomas
>> Rauch, Jun. claimed to be one of our recognized amplifier ''experts''
>> (9-94, QST) -- yet he has no training in physics, physics of electricity,
>> or algebra. The AL-1500 is the only 8877 amplifier that has no vhf
>> suppressor whatsoever. .
>>
>> Is either side of the heater operated at ground potential?.
>> thanks
>> cheers, Phil
>>
>> No Sir, it is wired just like you describe above....
>> cheers, Rich
>>
>> (((73)))
>> Phil, K5PC
>>
>>
>>
>>
>>
>> --
>> FAQ on WWW: http://www.contesting.com/FAQ/amps
>> Submissions: amps@contesting.com
>> Administrative requests: amps-REQUEST@contesting.com
>> Problems: owner-amps@contesting.com
>>
>
>
>--
>FAQ on WWW: http://www.contesting.com/FAQ/amps
>Submissions: amps@contesting.com
>Administrative requests: amps-REQUEST@contesting.com
>Problems: owner-amps@contesting.com
>
>
- Rich..., 805.386.3734, www.vcnet.com/measures.
end
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