Yep, same here Tom. I can't match my dipole any better than
3:1 on 10 meters with my tuner, so I use the Drake L-7 as a
buffer. The tuned input on my amp lets the solid state finals in
my exciter see a very low VSWR despite the crummy match
to the antenna.
73 de Mike, W4EF..................
----- Original Message -----
From: <n4kg@juno.com>
To: <TOWERTALK@contesting.com>
Sent: Wednesday, December 12, 2001 7:06 AM
Subject: Re: [TowerTalk] ++ High SWR and Modern Transceivers
>
>
> > Guys, all I asked was whether I could do any harm to my
> > transceiver by operating it into a high-SWR load, or at least one
> > high enough to cause the output power to be folded back by the
> > protective circuitry.
> >
>
> If the SWR causes excessive voltage in the PA, it will BLOW
> the output transistors. If the SWR causses current in the PA,
> it will cause excessive heat. Hopefully, the SWR protection
> circuitry is designed to prevent both, especially the high
> voltage scenario since that would be fatal. Excessive heat
> (current) would also cause the cooling fan to turn on giving
> you another clue. Since the transmitter still produces output,
> it is safe to assume that excessive voltage was NOT present.
>
> If these scenarios make you nervous, build an external antenna
> tuner for 160M, or use your amplifier as a buffer. My 160M
> elevated GP (140 ft) is seriously detuned when my 80M JA / SA
> inverted vee is suspended from a crossarm at the top of the
> tower (with isolated ladderline feedline). I still use it on 160M
> with 1400W forward and 400W reflected. In fact, it 'feels' more
> competitive with the additional top loading. The 3-500's in
> my amp don't seem to mind and I'm happy to have worked
> XZ0N, ZD9, and ZL9CI among others with that configuration.
>
> Tom N4KG
>
>
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