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#1
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OK - I just bought a new in the box 1955 Heath GD-1B grid dipper
with the extra low band coil set. $25. The dipper works FB and I used an old SO-239 chassis jack plus a bit of 22g wire and a cut down pill bottle to make a 4t coupling loop big enough to "dip" - that is I inserted the dipper's coil inside the pill bottle coil attached to my feedline. Now here is where I make myself look stupid - My antenna's best SWR is at 7185 with a 1.1:1 but the dipper showed max dip at 6990 (I tuned into the dipper with my K2). What's going on here? Someone educate me.....lol 73's de Ken KG0WX |
#2
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Resonance and VSWR are NOT related!
My 75 meter mobile antenna is resonant at 3.94 MHz. My VSWR is 5:1. You are measuring two different things. The dipper is a very nice tool. I owned the Heathkit unit in the olden days. I now use the Military surplus AN/PRM 10. KG0WX wrote: OK - I just bought a new in the box 1955 Heath GD-1B grid dipper with the extra low band coil set. $25. The dipper works FB and I used an old SO-239 chassis jack plus a bit of 22g wire and a cut down pill bottle to make a 4t coupling loop big enough to "dip" - that is I inserted the dipper's coil inside the pill bottle coil attached to my feedline. Now here is where I make myself look stupid - My antenna's best SWR is at 7185 with a 1.1:1 but the dipper showed max dip at 6990 (I tuned into the dipper with my K2). What's going on here? Someone educate me.....lol 73's de Ken KG0WX |
#3
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KG0WX wrote:
OK - I just bought a new in the box 1955 Heath GD-1B grid dipper with the extra low band coil set. $25. The dipper works FB and I used an old SO-239 chassis jack plus a bit of 22g wire and a cut down pill bottle to make a 4t coupling loop big enough to "dip" - that is I inserted the dipper's coil inside the pill bottle coil attached to my feedline. Now here is where I make myself look stupid - My antenna's best SWR is at 7185 with a 1.1:1 but the dipper showed max dip at 6990 (I tuned into the dipper with my K2). What's going on here? Someone educate me.....lol 73's de Ken KG0WX 1. Although it's usually close for simple antennas, the point of minimum SWR isn't necessarily the resonant frequency. The dipper measures resonance. 2. The coupling loop adds inductance to the circuit, lowering its resonant frequency. Roy Lewallen, W7EL |
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