[Amps] 50 watt stud mount zener diodes

[Carl]

----- Original Message ----- 
From: "Mike Tubby" <mike at tubby.org>
To: "Carl" <km1h at jeremy.mv.com>
Cc: <dhallam at knology.net>; <dezrat1242 at yahoo.com>; "Amps reflector" 
<amps at contesting.com>
Sent: Wednesday, August 11, 2010 12:12 PM
Subject: Re: [Amps] 50 watt stud mount zener diodes


>  On 11/08/2010 15:45, Carl wrote:
>> ----- Original Message -----
>> From: "David C. Hallam"<dhallam at knology.net>
>> To:<dezrat1242 at yahoo.com>
>> Cc: "Amps reflector"<amps at contesting.com>
>> Sent: Wednesday, August 11, 2010 10:03 AM
>> Subject: Re: [Amps] 50 watt stud mount zener diodes
>>
>>
>>> It's good that NTE can still supply them if needed, but their prices
>>> take you breath away.
>>>
>>> David
>>> KW4DH
>>>
>> Just another reason for 1N5408 or 6A10 strings. A tube arc will take out 
>> a
>> 50W zener as fast as a 10W version.
>>
>> Carl
>> KM1H
>>
>
> Carl, et al -
>
> 50W Zener diodes are now "hard to get" items in the UK - they are
> expensive, never quite the right voltage, noisy, and drift with 
> temprature.
>
> Have you considered making a "programmable Zener" using a TL431 and a
> TIP147 as per Ian G3SEK's "Triode Board" design (circuit attached).
>
> The full Triode Board info can be found here:
>
>         http://www.ifwtech.co.uk/g3sek/boards/triode/triode-manual.pdf
>
> the grid bias circuit is on page 11 (and attached) and can be built on
> its own.  I have substituted one in to a 50MHz 3-500Z amp (the QST 1970
> design) and it works great.
>
> This circuit is protected (assuming you have glitch resistors) by the 
> VDRs.
>
>
>
> Mike G8TIC


Mike, Ive used a similar SMD circuit for millimeter wave IC power amps and 
they have been fine. Havent considered them in this application though and 
should give it a try. Thanks for the reminder as Ive used Ians circuits 
before but with tetrodes.

Carl
KM1H