Antenna informtion needed

On Sat, 10 Apr 2004 16:19:25 -0700, Jim Weir wrote:

The VSWR at
the band edges with that sucker is something to behold. Remember, that antenna
was designed back in the days when 90 channels (118-127 on 0.1 MHz. spacing) was
just about airline quality.

Respectful, question, Jim: If he has a transistor output stage. . . .
(etc. etc.)

Don

Double whammy with a solidstate output stage. Back in the old vacuum tube days
we just said to hell with the reflective loss, let the RF output tube handle it.
So the plate glowed cherry red for a few seconds, no big deal.

Solid state "plates" don't glow cherry red but for a microsecond or so and that
snap you just heard was $100 worth of frenchfried silicon. So we got clever in
our old age and built in "VSWR Protection Circuits", which do nothing more than
reduce the available power in the transmitter output to something the
transistors can handle. You reduce the transmitted power by reflection and then
reduce it even further by the protection circuit.

Ain't no winnin' with a narrowband antenna and a 760 channel radio.

Jim



Don Tuite
shared these priceless pearls of wisdom:

-
-
-Respectful, question, Jim: If he has a transistor output stage. . . .
-(etc. etc.)
-
-Don

Jim Weir (A&P/IA, CFI, & other good alphabet soup)
VP Eng RST Pres. Cyberchapter EAA Tech. Counselor
http://www.rst-engr.com