| Author |
Message |
    
Road
New member
Username: Road
Post Number: 3
Registered: 11-2007
| | Posted on Monday, November 19, 2007 - 9:43 pm: | 
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Hi I just recently purchased a connex 4300-300 from copper. It is working really great and I am extremely happy with it. Problem is when I first hooked it up I used my astatic 636 with the payphone cord. A couple times when keying up I felt a shock or burn when my hand brushed where the cord meets the bottom of the mic. If I key up and touch this area it does not shock/burn me every time. I switched to the original connex mic that the unit came with and I was shocked by the metal circular mic clip on the back when keying up also(NOT EVERY TIME). Is there a bad ground in the radio or is it because I need to run a seperate ground to the radio? I don't know what the problem is and it only does it once in awhile. Your input would be greatly appreciated. Thanks, -Road- |
Kabar
Member
Username: Kabar
Post Number: 54
Registered: 6-2003
| | Posted on Tuesday, November 20, 2007 - 10:55 am: |
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Is your radio being used on a mobile setup?
What source of power are you using to power the radio vehicle battery or 12 volt AC power supply?
What kind of antenna are you using?
There are a number of things that can cause the problem you described.
More is needed to be known about your setup before steps can be performed to nail down the cause. |
Patzerozero
Senior Member
Username: Patzerozero
Post Number: 4014
Registered: 7-2004
| | Posted on Tuesday, November 20, 2007 - 3:46 pm: |
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actually, road, what you felt is commonly known as 'mic-bite'. it is caused by a bad RF ground, sometimes made worse by bad SWR. it is common in mobiles using amplifiers, bases in buildings on higher floors with no earth ground, and stations with too much coax/too many accessories inline not properly grounded/or just plain 'poor ground' causing a 'ground loop'. |
Road
New member
Username: Road
Post Number: 4
Registered: 11-2007
| | Posted on Saturday, November 24, 2007 - 1:28 am: |
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The radio is grounded well swr's are 1.3. |
Road
New member
Username: Road
Post Number: 5
Registered: 11-2007
| | Posted on Saturday, November 24, 2007 - 1:30 am: |
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So... I need to make sure everything is grounded well. Or are you saying it is a ground problem that exists inside the radio? |
Patzerozero
Senior Member
Username: Patzerozero
Post Number: 4018
Registered: 7-2004
| | Posted on Saturday, November 24, 2007 - 9:38 am: |
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no, it probably does not mean a bad ground inside the radio. swr of 1.3:1 does not neccessarily mean anything if there is a ground loop by way of coax, accessories, poor earth ground that is redirecting RF back into what should have been an electrical ground.
so, start us off with what is going on....connex 4300-300, i'm assuming base station here-on a power supply, going to an antenna. what antenna? what coax? length? any accessories in-line(meters, filters, tuners, amps)? what kind of and length of jumpers? back to filters-any? what kind? where installed? how? ground wire? size? length? grounded to what?
USUALLY 'mic-bite', especially when BAD, is more then a few 'bad things' of those listed above, compounding themselves into a shocking situation. YET, it is quite possible for a VERY POORLY set up station to have NO PROBLEMS.
let us know how things are set up, & we can give you an IDEA of WHERE changes may resolve the problem. |
Alsworld
Senior Member
Username: Alsworld
Post Number: 1024
Registered: 1-2002
| | Posted on Thursday, November 29, 2007 - 6:25 pm: |
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Road, Patzerozero told you right. A low SWR says you have a good ANTENNA ground. You are experiencing a typical ground loop problem which does not deal with the antenna, but how and where you have your radio and any accessories grounded to. Do an internet search on "ground loop" and you will understand much better. Lots of web pages dedicated to this subject (it's quite common).
There is no problem with the radio, just the installation concerning the radio ground. You can figure this one out easy and no more mic bite.
Alsworld
CEF 101 |
Captian_radio
Intermediate Member
Username: Captian_radio
Post Number: 277
Registered: 9-2004
| | Posted on Thursday, November 29, 2007 - 7:08 pm: |
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Try running what's called a counterpoise ground, basically its just a piece of wire grounded to the chassis of the radio and laid out under the floor mats , this wire should be at least a quarter wave length long at the freq. you are using IE 11 meters about 9 feet long. This can and will often absorb a lot of stray rf that is making the mic appear hot. You can conceal the wire so its not in view and not a tripping hazard.
Bob CEF451/VE1CZ
Robert L. Spicer The days of radio are just beginning!
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Road
New member
Username: Road
Post Number: 6
Registered: 11-2007
| | Posted on Friday, December 07, 2007 - 6:03 pm: |
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Thanks everybody for your responses. The radio is wired directly to the battery in my truck. The coax runs directly from the antenna (wilson silverload) to the radio and is grounded well. The coax is approx 8ft long. I will try running a ground off the radio that is 9ft long as you say and let you know the prognosis.
will the mic bite or ground loop damage the radio. another words should I not use the radio at all until I figure the problem out? |
Patzerozero
Senior Member
Username: Patzerozero
Post Number: 4044
Registered: 7-2004
| | Posted on Saturday, December 08, 2007 - 12:57 pm: |
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no....just be prepared to see your passengers' heads dent the roof as they jump if they key up with the metal mic casing touching their lip  .
in reality, coming in contact with 'rf' is probably not good for YOU, especially 300 watts from the connex. the fcc requires hams to be aware of 'rf' exposure and POSSIBLE consequences....POSSIBLE because at 27 mHz, and on the HF bands in general, the fcc actually states that there is no medically proven results as to what WILL happen with that amount of exposure, though what MIGHT happen is suggested. at much higher freqs, the concentration is greater due to shorter freq cycles-kind of how tighter isobars affect wind speed-and can damage eyes, skin, etc. |
