Terry,
I do not really intend to answer your questions about the switching the
feedline, that is up to you In the old days, we did that with a knife
switch, or more 'rich and sophisticated' hams used a DPDT relay.
For the balun, the impedance at the shack end will determine whether a
4:1 or a 1:1 will be a better choice. Measure the impedance on all
bands of interest with an antenna analyzer and use the results to figure
out which will be the better compromise.
The antenna feedpoint impedance will change from band to band, and the
length of the feedline will transform that impedance to something else.
If you have trouble matching it on any one band, try adding or
subtracting 1/8 wavelength of feedline for that particular band and
measure again.
73,
Don W3FPR
On 11/29/2015 10:17 PM, n7tb wrote:
I currently have a horizontal loop at my QTH being matched by an Icom AH-4
Tuner. It is interfaced with my Icom 756. I will be running a new-to-me K2
with the auto tuner installed. Right now, the loop is connected at its end
points to 450 ohm ladder that has one leg attached to the tuner's antenna
connector and the other leg to the ground lug. Coax comes from the tuner to
my rig and works great on my Icom 756. Now for the several questions.
1. the AH-4 interfaces with the 756 via a four conductor molex connector.
Is there some way to take those 4 wires and interface them to my K2 and let
the AH-4 tune the loop instead of the internal K2 tuner?
2. I presume it possible to take the coax feed from the A-4 off my 756, or
have an antenna switch do that, and attach the loop coax feed to my K2, then
turn on the 756 to the same frequency that I want to transmit on the K2, and
press the tune button on the 756 to tune the loop?
3. I could manually take 450 ohm loop antenna connection off the Ah4,
attach it to a balun attached to another length of coax that attaches to the
K2, but this is very cumbersome. Perhaps an antenna switch is available
that has two balanced feedpoints and a coax feedpoint that would allow me to
switch remotely? Does anyone know of such a thing?
4. If I decide to feed the 450 ohm twin lead to coax to my rig, what type of
balun do I need? 4:1 or 1:1?
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