Energized Imax 2K

[PtownBubba]

This is a wild story. My Galaxy Saturn,, went nuts. Not sure when it happened, but the short story is, it was putting out 120VAC at the SO239 on radio. YUP,,,, found out the hard way,,, unhooked the PL259 ,, and had my hands just right,, and got zapped. I then put a fluke meter, from the SO239 threads, to the PL259 body,,,, 120VAC. So,,, the 100' of rg8u went to a 30 ft. steel tower, buried 6 ft in the ground. The Imax was bolted to tower. With a now working Saturn,,, modulation was not very good according to reports,, and my Astatic 600 meter, Modulation was way better on a different antenna/coax setup.

So,, even though my Imax setup says it has a SWR of less than 1.5,, it is squashing modulation [ ??yea, I think so ] So, my question, is,,, if you pump 120VAC onto the shield of coax,,,, for who knows how long,,, what could happen ??

For one, I would have had a 'hot" tower,,, but not enough current flow maybe to bring up earthworms,,,, what was going on inside the Imax ? Is it not an 11 meter antenna anymore,,but,, something else ? What was going on in the coax,,, could I maybe replace both PL259's or did the coax get boogered up to point it will SWR ok,, but not work/transmit/receive worth a hoot ??

[Sandbagger]

Oct 15, 2009 22:51:06 GMT -5 PtownBubba said:

This is a wild story. My Galaxy Saturn,, went nuts. Not sure when it happened, but the short story is, it was putting out 120VAC at the SO239 on radio. YUP,,,, found out the hard way,,, unhooked the PL259 ,, and had my hands just right,, and got zapped. I then put a fluke meter, from the SO239 threads, to the PL259 body,,,, 120VAC. So,,, the 100' of rg8u went to a 30 ft. steel tower, buried 6 ft in the ground. The Imax was bolted to tower. With a now working Saturn,,, modulation was not very good according to reports,, and my Astatic 600 meter, Modulation was way better on a different antenna/coax setup.

So,, even though my Imax setup says it has a SWR of less than 1.5,, it is squashing modulation [ ??yea, I think so ] So, my question, is,,, if you pump 120VAC onto the shield of coax,,,, for who knows how long,,, what could happen ??

For one, I would have had a 'hot" tower,,, but not enough current flow maybe to bring up earthworms,,,, what was going on inside the Imax ? Is it not an 11 meter antenna anymore,,but,, something else ? What was going on in the coax,,, could I maybe replace both PL259's or did the coax get boogered up to point it will SWR ok,, but not work/transmit/receive worth a hoot ??

This is not as strange as you might think. Your antenna system is gounded, but on many radios, the chassis "floats", and will many times have a voltage potential on them. Many radios actually have a 2.2meg Ohm resistor from the hot side of the AC line to the chassis. With a high impedence voltmeter, you may see 120V between the "floating" chassis to ground, and if you disconnect the ground (AKA the coax), you may get bit by the voltage. But the thing is, while there may be 120V there, it is very LOW current (<1 ma). It won't kill you and it won't be there when the radio is connected to ground. Sometimes, you can lessen the effect by unplugging the power cord and swapping around the prongs and plugging it back in (If it's a non-polarized 2 pin plug).

I routinely get bit when I swap between my different rigs. I can also see very small sparks when I brush the coax connector against the chassis. It's normal. As for the radio seemingly not working properly, there's most likely another issue.

[PtownBubba]

I follow what you are saying S-bagger. This did not appear like static discharge,,, it was a teeth rattling shock,,, also I am aware that flukes are very sensitive to stray voltage, where an old analog meter may shunt out the stray voltage. I have hears of this coax shock before, on a 2980, it ws a lil' surge circuit board that failed. Even though ac equipment does really recognize polarity, like CD [pos-neg really matters] If you have an older 2 prong ac plug you can plug it in either way in the outlet and the equipment with operate either way. Newer plugs as you know have one blade wider, so it can fit one way, with the wide blade the neutral. But you can grind off that blade and use it either way. The old Saturn did not have a newer plug, so it would plug either way,,, I was gong to replace cord on Saturn with a standard 3 prong cord and plug, so any stray voltage should shunt out on the ground wire. Or if things were wrong or faulted inside the radio,, it would trip a breaker,,,,,,,,,,,,, or melt any weak stuff in radio,,,, ugh.



So,,, IF there was true 'unchecked" 120VAC,, [ like if you put an ac plug onto the coax and plugged it into an outlet ] traveling out from radio to coax, to Imax2k, mounted on a steel grounded tower would it damage the Imax