[ARC5] AN73 Antenna Coax Connector

[Mike Morrow]

Steve wrote:

> ...they did intend to use the antenna for the modern VHF comms
> antenna. I believe he said 118 to 13? Mhz

118 to 136 MHz.

> Based on the freq coverage provided by WA5CAB, it looks like the
> antenna that would be the best choice would be the AN-104 for the
> VHF Comms.

Yes, the AN-104 seems to be the best VHF mast of the war.  It was
used for many years after the war on older aircraft.  It requires
building a support base in the airframe to position and hold the
mast.

Taigh Ramey has photos showing the inside support for an AN-104 at:
http://www.twinbeech.com/radio.htm .

> A quick google for pictures of the 104 did not show any attachment
> means for the wire antenna though. Did it have any means of attachment,
> either built in or added on as an option??

Although exact details seem to vary a little depending on what version
of the AN-104 you have (I've got an AN-104-B) and the contractor that
made it, most will be manufactured with a hole (about 3/32 inch dia.)
about a half inch from the leading edge of the mast and about 2.5 inches
from the tip.  That's where the cord or cable that connects to the cold
end of the forward insulator for the SCR-274-N wire antenna is anchored.
I believe it must be non-conductive cord or, or very short, since it is
in contact with the radiating surface of the VHF mast.

> I found an AN-74 from a surplus outfit today, I believe we could get
> our hands on the right connector for the AN-73...

If you already have the AN-73, which Robert noted is rated to 125 MHz,
it should be sufficient to use that.  The lion's share of important VHF air
frequencies are below 125 MHz, and should that modern radio need to operate
up to the air band limit of 136 MHz, I doubt that any significant problem
would result.  The AN-74 seems to me to be the least desirable choice since
it covers the band segment least likely to be utilized, would still need to
be purchased (for some reason, ebay prices of the AN-74 run higher than
the more common AN-104), and would still need the same odd PL-P173 connector
that Robert described. 

> ...and I assume the AN-104 is out there somewhere too.

That would seem to be the best choice if you don't already have the
AN-73 mast.  At least it seems to have survived in greater numbers, and
requires only a common PL-259 UHF connector!

Most of these mast antennas have escalated in price in the past decade.

Mike / KK5F