[TenTec] Is there a beefier 2N5301?

[Denton]

Begs the question....why is the crowbar's clamp typically put across the 
output of a power supply instead of across the filter cap?
The crowbar's sence connection, of course, belongs at the power supply's 
output...but the clamp?
----- Original Message ----- 
From: "Bill Acito" <w1pa at hotmail.com>
To: <TenTec at contesting.com>
Sent: Tuesday, March 06, 2007 4:32 PM
Subject: Re: [TenTec] Is there a beefier 2N5301?


> Jerry,
>
> So what causes the pass transistor to fail? (my crowbar is after the pass,
> in the cable...   added after the first fail took out half the IC's on my
> Omni back in 1980 (under warranty, thankfully)...   if my crowbar trips, 
> it
> is because the pass has failed and it is protecting the rig, not to 
> protect
> the pass transistor).
>
> To that end, I seem to get a fail every couple of years. Is that because 
> the
> 252 was "under designed" i.e. not enough headroom in the 2N5301? too small 
> a
> heat sink for the application?
>
> If so, what is the best way to beef up the design? up the device? add a 
> fan?
>
> (and yes, obviously, I could just go out and plunk down for an Astron 
> 35...
> this rig has sentimental value, and I like running it as the original
> set-up)
>
> Bill
> W1PA
>
>
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