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Unread 02-17-2007, 01:25 PM   #1
PetervE
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Please help - CB has continuity!?

I installed everything correctly but when I was measuring my SWR I had over 3,4 and red... I measured the antenna and noticed I continuity with the ground...

I disconnected from the antennad from the SWR/CB everything was OK then with the antenna/mount and ground so eventually I traced it all back to the CB...

The CB disconnected from power and everything measures continuity at the antenna output/outlet on the back... Is the CB unit bad?

Please advise... I would greatly appreciate it...

Peter

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Unread 02-17-2007, 01:51 PM   #2
kencaz
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The center element should not have continuity with ground... That may be your problem. Check that your insulators are installed correctly.

KC
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Unread 02-17-2007, 02:35 PM   #3
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Quote:
Originally Posted by kencaz
The center element should not have continuity with ground... That may be your problem. Check that your insulators are installed correctly.

KC
I don't understand what you're saying (my apology)... When I take the CB without having it connected to anything power, ground, or antenna, I measure continuity between the outer side and the center of the antenna outlet on the CB itself. Is this supposed to be this way? It's sounds to me like a short internally... because when I connect the antenna I measure continuity on the coax or antenna mount as well and not when disconnected from the CB which it should be.

Thanks for the reply... any insight would be welcome....
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Unread 02-19-2007, 06:12 PM   #4
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You could likely have an internal short. The outside of the Male PL-259 connector on the CB should not show continuity with the center element connection.

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Unread 02-20-2007, 09:08 AM   #5
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When you say you measure continuity between the center conductor and connector shield what numbers are you talking? A short, a few kOhms, or even mOhms. You are probably expecting an open and you shouldn't.
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Unread 02-20-2007, 05:21 PM   #6
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The antenna is a short... that how current can flow in the system and allow the transmitted power to flow.

If you remove the coax connector from the CB and check the resistance from the center pin to the outside of the PL-2590 Connector, it will read shorted.
If you remove the coax from the antenna mount and check between the center conductor and the shield it will read shorted.

The trick is to keep the coax by itself from being shorted.

With an SWR in the 3 or 4 rang, start by checking the coax for a short.
Then make sure you have a good ground from the antenna mount to the frame and double check the shield of the coax (the outside of the PL-259) and the mount.

Check the assembly of the antenna stud mount making sure the fiber washer is in the correct place.

You don't want the center conductor to ground out or short to ground, until the transmit power has gone up the antenna and came down again.

ltr
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Unread 02-20-2007, 07:01 PM   #7
Dcomf
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Quote:
Originally Posted by NnF


The antenna is a short... that how current can flow in the system and allow the transmitted power to flow.

If you remove the coax connector from the CB and check the resistance from the center pin to the outside of the PL-2590 Connector, it will read shorted.
If you remove the coax from the antenna mount and check between the center conductor and the shield it will read shorted.

The trick is to keep the coax by itself from being shorted.

With an SWR in the 3 or 4 rang, start by checking the coax for a short.
Then make sure you have a good ground from the antenna mount to the frame and double check the shield of the coax (the outside of the PL-259) and the mount.

Check the assembly of the antenna stud mount making sure the fiber washer is in the correct place.

You don't want the center conductor to ground out or short to ground, until the transmit power has gone up the antenna and came down again.

ltr
Gotta ask. Why would it read a short from the conductor to the shield on the cb output connector? I'm asking out of curiousity.
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Unread 02-21-2007, 04:23 AM   #8
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Quote:
Originally Posted by Dcomf
Why would it read a short from the conductor to the shield on the cb output connector? I'm asking out of curiousity.



First I am not talking a dead short.

It is all in the PCB inside. Everything has to have a positive and negative in order to create the signal that transmits voice, so the components are connected but remember that the resistance reading measured will be small.
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Unread 02-21-2007, 09:07 AM   #9
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Quote:
Originally Posted by NnF


First I am not talking a dead short.

It is all in the PCB inside. Everything has to have a positive and negative in order to create the signal that transmits voice, so the components are connected but remember that the resistance reading measured will be small.
I knew there was resistance that's why I asked. A short is just that, a short. If there is resistance it isn't a short, even if it's only 1 ohm. And it's not the PWB (PCB) providing resistance, that is just a bare board. Once it is stuffed with components then it becomes a PWA and you have some resistance. Just clarifying
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Unread 02-21-2007, 09:15 AM   #10
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Peter came over to my house Sunday and we got his antenna tuned. It turns out there was no problem with his CB, I measured it with my VOM and found no problem. His digital meter did for some reason but then I trust my cheapy old fashioned VOM more for this kind of work than those fancy-schmantzy digital meters anyway.
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Unread 02-21-2007, 12:44 PM   #11
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Quote:
Originally Posted by Jerry Bransford
Peter came over to my house Sunday and we got his antenna tuned. It turns out there was no problem with his CB, I measured it with my VOM and found no problem. His digital meter did for some reason but then I trust my cheapy old fashioned VOM more for this kind of work than those fancy-schmantzy digital meters anyway.
Yes... Jerry helped me out very much so...

When measuring the resistance (Ohm) and not through a diode test at the CB outlet for the antenna we saw no continuity (even on my digital ). We also removed the spring and only use the disconnect/stud. Jerry attached a ground cable to the antenna and the chasis with no major improvement indicating that ground was OK. When started tuning the antenna via the screw on top (Firestik II), Jerry was able to bring the SWR to a 1.7 which works just fine for me and also transmits perfectly with the engine running and no noise (power is straight from the battery, gound from the chasis).

Thanks again Jerry....

Peter
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