[Lowfer] I am now Simultaneously Transmitting and Receiving

[Lewis Denton]

Ralph, you are back to your 35/40 db over the noise today around Noon.
don't know how you keep it out of the receiver.
Lewis

Subject: [Lowfer] I am now Simultaneously Transmitting and Receiving


> 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
> 
> 
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