[R-390] R-390 Balanced Antenna Input

[Glen Galati]

Hello Walter & Group,
Was this WE754 CABLE SHIELDED AND WHAT IS THE IMPEDANCE?
I have a balanced coaxial cable jumper that is RG-22B/U and is terminated
with UG-421 Amphenol TWIN-AX male connectors.  The Impedance is 95 Ohms @ 16
pfd/ft.  This coax was made by I.T.&T. Federal Cable. I know that the
Velocity  of Propagation increases with Impedance increases. Most of our
RADAR equipment used RG-62 coax when outside the waveguide environment. In
all my years in the Air Force I never saw balanced antenna lines used. I may
have missed some important thread explanation on the subject of the OR-390
Balanced Input, so I'm not up to speed on which produces the best results.
QUESTION: On a side by side comparison with say two dipoles cut to the same
frequency WITH one using balanced feed-line and the other coax, which would
win out?  There is an interesting coax by BELDEN 9857 (MIL-C-17F) RG-63 that
is 125 ohms, 84% V.F. It has two shields (1-copper & 1 tinned copper) very
low loss 1.5 db/100 ft. The center conductor is solid 22 AWG and is a copper
clad steel. There are also  two BELDEN 124 Ohm TWIN-AX #9271 (66%VF) & 9860
(78% VF).  I haven't seen this coax and anyone with an interest can surely
get all the specs from the Belden website.

73,
Glen Galati, KA7BOJ
TACOMA, WA
eldim at worldnet.att.net


----- Original Message -----
From: "Walter Schulz" <k3oqf at localnet.com>
To: <r-390 at mailman.qth.net>
Sent: Saturday, June 26, 2004 9:34 AM
Subject: [R-390] R-390 Balanced Antenna Input


Regarding the balanced Antenna Input. Western Electric use to make WE754
Cable which was double shielded and used for the transmission of video. DB
loss per 100 feet at 148 Mhz was less than 1DB.

There were two leads, white was the tip, and blue was the ring side. The
connectors were made by AMP connectors, and would assume they are still
available.

Using for WE754 for ham radio or unbalance, simply twist the white and blue
wires together and solder. The input impedance becomes approximately 52
ohms.

I thought this might be helpful to all who own R-390A receivers.

Walter
_______________________________________________
R-390 mailing list
R-390 at mailman.qth.net
http://mailman.qth.net/mailman/listinfo/r-390