[Kenwood] TS930/940 PA modules.

Thu, 6 Feb 2003 17:29:31 -0500

  With that in mind, it may not be a bad idea to place a
5 or 10 watt 30 volt zener acrossed the +28 volt supply
to the outputs with a series fuse. If the pass transistor shorts
then at least there a little less chance of the final getting
smoked in the process, cheaper to replace a zener than
a final.

Mark  WB8JKR

On Thu, 06 Feb 2003 16:15:42 -0600 "Dr. Gerald N. Johnson, electrical
engineer" <[email protected]> writes:
> The 930 and 940 use 28 volts on the PA and driver transistors like 
> some
> other radios of that and more recent eras. That allows for a bit 
> more
> power and better linearity.
> 
> There is a company that sells kits for amplifiers based on Motorola
> applications notes, some bipolar, some MOSFET. RF parts sells them 
> too.
> It would be sacrilege to scrap the 28 volt amplifiers and power 
> supply
> and drop in a 12 volt amplifier, but the 12 volt PA at 100 watts 
> output
> seem to be less prone to self destruction. Some of the MOSFET 
> amplifiers
> are very good and run better on 28 volts.
> 
> One should be wary of the 28 volt power supply. If it gets high from
> shorted pass transistors, I suspect the PA and driver transistors go
> soon afterward from over voltage.
> 
> Then while they can't sell it in the US as a kit, Elekraft makes a 
> 100
> watt 12 volt amplifier too that might be arranged to drop into 
> classic
> solid state radios.
> 
> I've not tried any of these, just throwing out some ideas.
> 
> 73, Jerry, K0CQ
> 
> -- 
> Entire content copyright Dr. Gerald N. Johnson, electrical engineer.
> Reproduction by permission only.
> - - -
> 
> Your moderator for this list is:
> Larry Wilson KE1HZ [email protected]
> 
> _______________________________________________
> Kenwood mailing list
> [email protected]
> http://mailman.qth.net/mailman/listinfo/kenwood
> 

________________________________________________________________
Sign Up for Juno Platinum Internet Access Today
Only $9.95 per month!
Visit www.juno.com