m II writes:

Telamon wrote:

Instead of just disconnecting the radio and ground you might also want
to connect the coax center conductor and shield together at that switch
point.



The induced voltage in the antenna has an instantaneous vector value.
Same on the outer sheathing of the coax. When the signal in the sheath
is redirected to the inner conductor, it will, in effect, be changing
direction.

Have your tried reading "Transmission Line Transformer Book" by Jerry Sevick? I was able to get a copy from a local library using their loan program! They actually found a copy. It is very interesting.

I have been wanting to read ``Theory and practical designs for the experimenter'' By Jerry Sevick, W2FMI. 115 pages. It is hard to come by these books. Also the materials listed in the books are not your standard amidon mix#. Getting baluns to work would probably necessitate a nice signal generator, and hopefully spectral analyzer, to say the least.

I do have a circuit for measuring forward and reflected radio waves - unfortunately I do not have a shielded enclosure to attach the two metters... It's still laying on some copper clad ...

[ ... damn... ] I was going to scan the schematic but the scanner is complaining about windows 7 missing some kind of internet fax twain device. A wireless fax machine. So new and inventive.

Anycase; Bill Hickox, K5BDZ ``only an swr meter''. I should take head and advise myself it is probably better to buy a professional SWR meter, but I can't even find a damn aluminium box... Autocenter meters - try dans small parts...

That changed direction will be in opposition to the signal in the main
antenna wire.

reflected swr.

I'm thinking that the length of the coax will in effect be subtracted
from the antenna length, not added as I had previously thought.

watch for standing waves.

The antenna, apparently, is only as long as the wire portion MINUS the
coax length.

velocity factors as well.

This is all assuming that the switch is indoors, at the very end of the
coax, not where the antenna joins the inner conductor.

yeah like finding radio grade coax that hasn't been cut to pieces by comcast yet.


mike

steve