"Lloyd Bonafide" wrote in message
...

"Wilbur Hubbard" wrote in message
anews.com...
"Hanz" wrote in message
...
Can I use the 735 without the antenna tuner to only receive signals (no
transmission)? What happens if I key the mike without the antenna
tuner?

Thanx.




The purpose of an antenna tuner is to electronically lengthen or shorten
the physical antenna so as to better match the wavelength of a particular
broadcast frequency. Whole waves, half waves quarter waves are better
than some random wavelength chopping when it comes to propagation and
reception on the other end.

Operating without the tuner will not harm your transmitter. It will only
degrade its transmit efficiency somewhat.

Cross-posted to AFPF in the hopes that one Lloyd Bonafide who is a radio
expert might comment and affirm my thoughts.

Wilbur Hubbard


For maximum power transmitted from the radio the antenna impedance has to
be the complex conjugate of the output impedance of the radio transmitter.
So the antenna and radio must have the same resistive (real) impedance and
their reactive (imaginary) impedances must sum to zero. If the impedances
are not matched, the voltage waves from the transmitter will reflect from
the antenna input and travel back to the transmitter. The could result in
heating of the output amplifier and eventually lead to its destruction.
The antenna length determines its input impedance and radiation pattern.
The tuner, at its simplest, is an electronic network, usually pi
configured, and works to transform the real part of the two impedances to
be equal at a given frequency and the reactive parts to be zero. Multiple
pi stages allow greater tuning ranges.

Bottom line, you can probably get away with short transmissions (like in
aircraft) and intermittently heat up your output stage. If your life
depends on it, get a tuner. You can use an SWR bridge to measure the
degree of mistune:

http://www.packetradio.com/catalog/i...oducts_id=2174

The amateur radio gear will work for marine radio, for $40 it's a handy
thing to have, considering a shop will charge you more for the service.

You can receive without damage with no tuner.
You may damage the radio by transmitting without a tuner.

I just looked up that ICOM-735. It's an amateur radio rig, I thought you
were asking about marine radio. Do you have a license to operate it? If
you did you wouldn't be asking that type of question and you would know
how to get around the heating up the output stage. If you don't have a
general class or better license, don't operate that radio - it's illegal.
Keep the stooges on the internet and off of the airwaves.




Poor Hanz (OP) does sound pretty clueless. And, as massively intelligent as
I am I can't really understand, intuitively, a lot of what you wrote but I
believe it as your, sir, are the expert par excellence. I couldn't help
noticing how soundly you humiliated one BobG in such a discussion and many
others.

The topic sure is more complicated than I thought, but, then again I would
not have an amateur radio transmitter aboard. Just so much power-hogging
clutter to detract from the real reason to be out there cruising. Besides,
what's wrong with a sat phone? Why operate in the dark ages of amateur radio
semi-reliability?


Wilbur Hubbard