[AMRadio] How much is too much?


Brett gazdzinski brett.gazdzinski at verizonbusiness.com
Fri Jan 19 14:56:15 EST 2007


Thanks for the info!
The 4d32 rig runs 300 watts out, the that should be a 
good test of things.
The big rig runs twice that, so I will need to build something
better, but the small matchbox should do for tests with
the little rig.

Brett
N2DTS 

> -----Original Message-----
> From: amradio-bounces at mailman.qth.net 
> [mailto:amradio-bounces at mailman.qth.net] On Behalf Of Geoff/W5OMR
> Sent: Friday, January 19, 2007 2:45 PM
> To: Discussion of AM Radio in the Amateur Service
> Subject: Re: [AMRadio] How much is too much?
> 
> Brett gazdzinski wrote:
> >  
> > I have been watching Johnson matchboxes on ebay,
> > and the KW ones go over $300.00 and I 
> > don't want to spend that much as I plan on
> > building something once I get the parts and design
> > figured out.
> > Once the antenna stuff arrives, I plan on putting up
> > about 100 feet of dipole fed with homemade open
> > wire line, in place of the 40 meter dipole, so
> > I need to get it to work if I want to be on the air.
> > The Johnson 275 watt (250?) matchboxes are less, good to
> > experiment with, can they handle 275 watts of AM?
> >
> > Anyone know?
> 
> I don't see why the 275 matchbox wont work for you.  Goodness knows, 
> it's built as well as these 'so-called' kilowatt matching devices of 
> current day.
> 
> I'd be careful to apply full carrier to the device if it's 
> not in tune 
> though.  I did that by accident, moving the rig back to 3.880Mc from 
> 3.650 using a Heaktkil SA-2060 2kW impedance matching device.  Moved 
> back up band, and hit that thing with about 300w into a non-matched 
> load, and there were lightning flashes coming from behind the 
> meters.  
> The metering is all but gone.  It will still measure SWR 
> (kinda / sorta) 
> but a maximum of 5w of output, and I -know- I'm running 150w 
> DC input to 
> the final.
> 
> As long as you're close to being matched, I feel reasonably sure that 
> the 275 will probably carry 300w of carrier.
> 
> --
> 73
> 
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