Thanks for the advice Jeff,
All points noted.
I must confess that all of the published designs seem to use a logic driver
IC.
I must be being awkward using an inductor :-(
Maybe I'd better stick to a proven design..
I'll take a photo soon and risk ridicule - HI!
73 Chris G3XIZ
-----Original Message-----
From: F6CWN [mailto:[email protected]]
Sent: 28 September 2005 10:21:AM
To: [email protected]
Subject: LF: Re: Advice will be gratefully received
Hello Chris,
At first,"RIP poor MOS"!
I prefer use MOS with higher VDS.
The driver must absorb energy, because the Ciss capacitance, i use TSC426 or
TC4429 driver.
It sis better to separate the cooling radiators to minimize the reaction
between the two parts
of the bridge (capacity Drain / Ground, the ground is "hot").
A problem with reactive loading, the coils of the LPF are reversible.
A little photography of your PA can help...
73: Jeff / F6CWN/p
----- Original Message -----
From: "OSBORN, Chris" <[email protected]>
To: "LF Group (E-mail)" <[email protected]>
Sent: Wednesday, September 28, 2005 10:43 AM
Subject: LF: Advice will be gratefully received
The PA FET's in my new home brew transmitter keep exploding !
I'm using push-pull IRF520's rated at 100 V Vds and my supply is 30
volts.
I am careful not to exceed the V gs.
The gates are driven with a toroidal transformer and the whole
circuit is just a scaled up version of my original TX, which works fine.
It generates healthy power into a 50 ohm dummy load but on
connection to the aerial circuit - bang !
The aerial system is identical to that used with the old TX !
Has anyone any ideas on what's causing the problem and how to cure
it ?
I'm running out of FET's and my nerves are somewhat frayed (shell
shock!)
73 Chris G3XIZ
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