Re: Topband: New Linear amp
Tom W8JI <w8ji <at> w8ji.com>
2012-07-07 22:58:29 GMT
> The new Harris Flexiva 10 KW FM band (not pulse) stereo transmitter is
> having a heat problem with air cooling, in a reasonably small package . It
> has individual modules that can be hot switched.
I'm sure Harris did a great job. The modules can be swapped while the TX is
on, even power supply modules, which is a nice feature. But hot or live
swapping does not mean the modules are "hot switched", as in allowed to have
no load while amplifying. Generally a module is designed to remove power
first when pulled, and apply power last when plugged in, which is nothing at
all like some ham transmitting with an arcing tuner, or without a feedline.
You will also note Harris protects the modules, which is what everyone
should do. VSWR ratings in data sheet are really useless marketing hype,
because near full power in longer duty cycle modes, as little as a 2:1 VSWR
can blow a device out.
My point is about Ham gear use where people are thinking they do not need to
watch SWR or other parameters. There is little worry in a commercial
transmitter that runs the device at 600 watts or less per device with
adequate protection for SWR and thermal issues, and most likely current
We should not translate what Harris did into something with no thermal
protection, no SWR protection, and twice the power on the device!!
> The Harris Salesman, Engineer, Ham, said there was already a W2 using a
> pair, but had a small water cooled system.