[Moon-net] New Device maybe for 1296 amp ?

[Paul Chominski]

Those are common base devices. For linear operation requires negative 0.6to 
0.7 V  temperature compensated bias accross entire collector current. I've 
been on this path years ago using common base transistors for 2.3 GHz.
Anyway, it looks interesting if those transistors are available for 
reasonable price.
VY 73 Paul WA6PY

----- Original Message ----- 
From: "Chris Bartram" <chris at chris-bartram.co.uk>
To: <moon-net at list-serv.davidv.net>
Sent: Saturday, June 30, 2007 3:28 PM
Subject: Re: [Moon-net] New Device maybe for 1296 amp ?


> The limitation with so-called 'long-pulse' radar transistors used as CW
> devices is usually die temperature. While it might be possible to get 
> 150 -
> 200W CW from a 800W 10% duty cycle pulse transistor while maintaining a
> sensible junction/channel temperature, to do it reliably would involve 
> taking
> the cap off of the device and measuring it, preferably with a suitable
> scanning infra-red themometer.
>
> I wouldn't bother to try unless I had a big supply of devices at zero 
> cost!
>
> There are devices - both bipolar and (LDOMOS) FET - which will give 100W+ 
> CW
> at 1296. These are engineered to operate under CW conditions, and with
> attention given to proper cooling - something neglected in many amateur
> designs - will be a lot more reliable than a big long-pulse device 
> operated
> under an uncertain thermal regime.
>
> Vy 73
>
> Chris
> GW4DGU
>
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