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Topband: BOG questions

Subject: Topband: BOG questions
From: Mikek <>
Date: Fri, 23 Aug 2019 12:21:12 -0500
List-post: <>
Sorry I can't see if there is a way to reply specifically to the OP's question on the reflector, so, I just put in the Subject.  Ok, I'm learning as I go, but I had a 250ft bog with variable termination. I never saw that they are self terminating.  I used it more on the BCB than 160M, or 80M. But it was the quietest of the three antennas I had up. Unfortunately we had a hurricane and the owner of the property brought in bulldozers and backhoes to clean up the property and my BOG is gone.  Here a comparison of the antenna in the BCB. Note: I'm in the panhande of FLorida and there was a lightning storm out in the gulf. That is a good test for me because that happens a lot.
 I bought a Rig Experts AA-35 to measure my antenna. and built the transformer accordingly. I don't recall the numbers and don't want to look for them.  When I build another one, I'm going to compare a transformer to Dallas Lankfords 2 FET amp. Find it on page 7 here,
 There was a change of a resistor, this version has that change, the 820k as 1M, I think IP2 was increased with the 820k resistor.  The advantage of the 2 FET amp is it unloads the antenna, giving you 3 db more signal and it eliminates the impedance transformer as it has a near 50 ohm output, so then (not sure about this) you don't have voltage ratio of the Impedance (stepdown) transformer, giving you another 10db voltage increase. (correct me if I'm wrong)

 Some impedance meters don't do well at 300  or 450 ohms, so you need to wind a transformer meter, say a 450 to 50 ohm and then measure your antenna, and crunch the numbers.

 Something from reading all of Dallas Lankfords work on very directional antennas, any feed line ingress destroys the pattern. His solution was to use twisted speaker wire. Now Cat5 or Cat6 wire is now being used. I was skeptical and did my own test, running out 200 ft of RG58 and 200ft of twisted speaker wire. I did 50 and 100 ohm terminations, opens and shorts. The coax picked up more AM BCB signals and at much higher levels than the twisted speaker wire. The speaker wire was pretty dead, from memory, I think I only heard 3 local stations at very low levels.
 So I used the twisted speaker wire and was very happy with my BOG.
 I have had people say you had bad coax, you didn't terminate it properly (I did) and other things. I would like to see a new thread on just that subject. "Signal ingress, coax vs twisted speaker wire."  I'm in the process of getting data to build a new BOG. I want mine usable from 500kHZ to 4MHz.  From my limited understanding inductive loading the antenna will help to make it more directional at the 500 kHz frequency, but that same loading well cause a poor pattern as the frequency increases.
(I'll start my own thread on this)
I had nine bead/sleeves spaced out along the length of my bog. I have new info that my beads were far from optimal. I don't model, but would love to have the information it provides.

                             Hope you glean a something from that,  Mikek

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