----- Original Message -----
From: "Bill, W6WRT" <dezrat1242@yahoo.com>
To: <amps@contesting.com>
Sent: Tuesday, October 19, 2010 6:35 PM
Subject: Re: [Amps] AL-1200 debug at a distance: we might have
awinner(W5GHZ)
> ORIGINAL MESSAGE:
>
> On Tue, 19 Oct 2010 12:14:35 -0700, "knormoyle@surfnetusa.com"
> <knormoyle@surfnetusa.com> wrote:
>
>>
>>The 50W versions need a larger mounting hole (1/4")
>>which is doable, but I'd also need the 1/4"
>>insulating hw.
>
> REPLY:
>
> I don't have an AL-1200 in front of me to see if this is feasible, but
> here's a thought:
>
> Install the two new zeners (50 watt) on a small piece of aluminum sheet
> and mount the sheet directly in the airflow outlet of the fan or blower.
> Bypass them well for RF and you can mount them at any reasonable
> distance from the tube. Install bypass caps both at the zeners and at
> the tube socket.
>
> If you order one with the cathode to the stud and the other with the
> anode to the stud you can dispense with the insulated mounting hardware
> and bolt them directly to the aluminum. Then just "float" the aluminum
> electrically on some standoff insulators.
>
> This is what I did in my homebrew amp and the cooling is excellent.
>
> The last time I checked, Newark carried the 1N33XX series of 50 watt
> stud mount zeners, in both mounting polarities.
>
> 73, Bill W6WRT
> _______________________________________________
This is only a single tube amp that doesnt make much over 1500W with 100W of
drive. There is an ample front to rear aluminum shield that is more than
adequate to dissipate the 8W or so in normal use.
As already mentioned use thermal compound plus be sure to get the mounting
kit when ordering.
Carl
KM1H
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