[Lowfer] I am now Simultaneously Transmitting and Receiving

[W5JGV]

Hooray!!  Success at last!

This afternoon I managed to set things up so that I can now transmit on
166.5 KC with 400 watts, and simultaneously receive on 185.3 KC.

What I did was to build a two-turn shielded loop antenna from 1/2"
aluminum Cable TV hardline, and tuned the loop to 185.3 KC with a
combination of selected film and Mica capacitors.  I placed the loop
about 23 feet away from my 166.5 vertical transmitting antenna, and
adjusted the loop to null out the signal from the transmitter.

The null is not perfect, but it's good enough so that my HP-3586 is
happy with it, and so is ARGO.  I'll build a tuned preamp for additional
rejection of my TX signal, and to make up for the loss in gain of the
loop - which is about 6 to 10 dB poorer than my vertical antenna.

A quick picture of the loop (and me looking stupidly at the camera) may
be seen at
http://www.w5jgv.dyndns.org/files/RX_Loop_Antenna/Loop_HPIM1151.jpg
This picture was taken a couple of days ago before the tuning capacitors
were installed, and the feedline connected.  I'll do a complete write-up
for my web site about the antenna as soon as I get some free time.

The loop is oriented so the plane of the loop (and hence the major
lobes) is on the 45 / 225 degree (true North) axis.  It is presently
feeding the online ARGO viewer at http://www.emachine.com/argoview.htm

My WC2XSR/13 transmitter is now back on the air on 166.5 KC @ 400 watts,
modulation QRSS30 and 10 WPM CW ID.  Reception reports invited.  The
antenna current meter and frequency counter for the transmitter is
viewable at http://www.w5jgv.dyndns.org/wc2xsr_13.htm  The transmitter
logging function is not available at present, due to software problems.

Loop Antenna Preliminary Info:

  Diameter = 10 feet
  Turns = 2
  Turns spacing = 3" center-to-center
  Turns spacers = Notched lengths of 1/2" PVC pipe
  Loop conductor = 1/2" aluminum CATV hardline
  Frequency range = 56 KC - 2125 KC
  Type of loop = Shielded conductor, balanced tuning, isolated from
ground
  Tuning = Manually Switched 14 bit binary capacitor bank
  Smallest tuning capacitor = 12 Pf
  Largest tuning capacitor = 0.1 Uf
  Weight of antenna, less base and internal stiffening pipe = 25 Pounds
  Weight of base and stiffening pipe = 88 pounds
  Frame = PVC pipe, with poly rope stabilizers
  Center Mast = 2" PVC pipe
  Stiffener pipe = 1-1/2" iron pipe inside center mast, extends 12"
above cross arm.
  Cross arm = 1-1/2" PVC pipe
  Loop conductor diameter = 2.5 MM
  Shield diameter = 12 MM
  Feedline = 75 Ohm
  Coupling, Loop to Feedline = Ferrite core transformer, 1:10 step-up to
feedline.

73,

Ralph   W5JGV - WC2XSR/13

http://www.emachine.com