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Link Antenna Coupler




 
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Author Topic: Link Antenna Coupler  (Read 2714 times)
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aa5wg
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« on: May 14, 2010, 11:28:54 AM »

Hi to all:
(1) The Radio Handbook, 23th Edition, William I. Orr, W6SAI, page 22-16 shows a series capacitor in the link circuit placed on the OUTPUT side of the link coil to ground.  The Radio Handbook, 20th Edition, William I. Orr, W6SAI, page 26-19 shows a sereis capacitor in the link circuit placed on  the INPUT side of the link coil.

Which location (input side vs. output side of link coil) of the input capcitor in series with the link coil is best and why?

(2) The Radio Handbook, 23 Edition, William I. Orr, W6SAI, page 22-16 has the link input coil cut in half.  This allows the two link coils to be placed in sereis or parallel depending on the band in use.

Can the tank output coil also be cut in half allowing for series or parallel connection to each other for the different bands?

73,
Chuck Pool - AA5WG
Cedar, Michigan

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WA1GFZ
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« Reply #1 on: May 14, 2010, 11:36:55 AM »

Most caps have a frame connection to the rotor so it is a lot easier to put the cap on the ground side of the link rather than floating the cap on the high side which requires an insulated shaft to the knob.
#2 is yes or you can put two caps in series with 1 secondary coil and drive them with a common shaft an dan insulated coupler between them.
This is called series tuning and usually used when the feedline reflects a low impedance at the feed point.
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aa5wg
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« Reply #2 on: May 15, 2010, 07:33:34 AM »

WA1GFZ:
Thank you for your information.
Anyone else have any additional information?
Chuck - AA5WG
Cedar, Michigan
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aa5wg
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« Reply #3 on: May 15, 2010, 08:59:51 AM »

I am going to cut the antenna ouput tank coil in half and feed the antenna terminals in series with the two coils.  

If these two series coils, now left and right output coils, (with the tank capacitor connected between them) are large I am going to cut each of them in half and place them in parallel.  Now I have two coils in parallel on the left side of tank capacitor and two coils in parallel on the right side of the tank capator.  This will, I think, lower inductance values needed for the higher frequencies like 10 meters.  

I now have two inductors in parallel on each side of the tank output capacitor feeding the antenna terminals in series.

Will the above configuration increase potential of circulating currents in a link antenna coupler?

73,
Chuck - AA5WG
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WA1GFZ
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« Reply #4 on: May 16, 2010, 06:36:58 PM »

depends on the load z
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