• To anyone looking to acquire commercial radio programming software:

    Please do not make requests for copies of radio programming software which is sold (or was sold) by the manufacturer for any monetary value. All requests will be deleted and a forum infraction issued. Making a request such as this is attempting to engage in software piracy and this forum cannot be involved or associated with this activity. The same goes for any private transaction via Private Message. Even if you attempt to engage in this activity in PM's we will still enforce the forum rules. Your PM's are not private and the administration has the right to read them if there's a hint to criminal activity.

    If you are having trouble legally obtaining software please state so. We do not want any hurt feelings when your vague post is mistaken for a free request. It is YOUR responsibility to properly word your request.

    To obtain Motorola software see the Sticky in the Motorola forum.

    The various other vendors often permit their dealers to sell the software online (i.e., Kenwood). Please use Google or some other search engine to find a dealer that sells the software. Typically each series or individual radio requires its own software package. Often the Kenwood software is less than $100 so don't be a cheapskate; just purchase it.

    For M/A Com/Harris/GE, etc: there are two software packages that program all current and past radios. One package is for conventional programming and the other for trunked programming. The trunked package is in upwards of $2,500. The conventional package is more reasonable though is still several hundred dollars. The benefit is you do not need multiple versions for each radio (unlike Motorola).

    This is a large and very visible forum. We cannot jeopardize the ability to provide the RadioReference services by allowing this activity to occur. Please respect this.

SWR Tuning/Antenna ground

Status
Not open for further replies.

scanner90

Member
Joined
Feb 19, 2008
Messages
12
Location
Seattle, WA
Well I've got a realistic radio that was hooked up to a junk radio shack antenna and lets just say I was better off rolling down my window and shouting across the road at whoever I was trying to talk to.

So I bought a 5ft Wilson FGT antenna, some quality coax(forget the brand) it said something like mini-8 and 95% shielding, as well as a roadpro SWR meter.

I've got the antenna mounted on my front bumper which might not be the ideal spot but it's the best compromise for my use.

Anyway I hooked up the meter and couldn't get it to work right, it was pegging the needle on some channels and almost pegging on others. I tinkered w some stuff but never got it working right.

So after testing the mount and coax w a multimeter as well as other stuff I found out that if the mount wasn't grounded that it all worked fine. I got another nylon washer and installed it on the bottom of the mount so the outer part of the coax connector isn't grounded at all. I bolted everything back on the bumper and grounded the ground wire from the antenna.

This time the gauge worked just as described in the book and after adjusting the tuning stub I have an SWR between 1 and 1.3 on all channels.

My question is does this sound right? I'm new to CBs but I though the mounts were supposed to be grounded?? Maybe since the Wilson has the ground wire it's different? I'm hoping I didn't just "trick the meter" and still have a problem. It seems to get great reception(much better than the old setup) but I haven't tried transmitting yet.
 

Allan_Love_Jr

Member
Joined
Dec 4, 2005
Messages
881
Location
Blair,Nebraska
Well I've got a realistic radio that was hooked up to a junk radio shack antenna and lets just say I was better off rolling down my window and shouting across the road at whoever I was trying to talk to.

So I bought a 5ft Wilson FGT antenna, some quality coax(forget the brand) it said something like mini-8 and 95% shielding, as well as a roadpro SWR meter.

I've got the antenna mounted on my front bumper which might not be the ideal spot but it's the best compromise for my use.

Anyway I hooked up the meter and couldn't get it to work right, it was pegging the needle on some channels and almost pegging on others. I tinkered w some stuff but never got it working right.

So after testing the mount and coax w a multimeter as well as other stuff I found out that if the mount wasn't grounded that it all worked fine. I got another nylon washer and installed it on the bottom of the mount so the outer part of the coax connector isn't grounded at all. I bolted everything back on the bumper and grounded the ground wire from the antenna.

This time the gauge worked just as described in the book and after adjusting the tuning stub I have an SWR between 1 and 1.3 on all channels.

My question is does this sound right? I'm new to CBs but I though the mounts were supposed to be grounded?? Maybe since the Wilson has the ground wire it's different? I'm hoping I didn't just "trick the meter" and still have a problem. It seems to get great reception(much better than the old setup) but I haven't tried transmitting yet.
If the SWR is down to 1.1:1 or say. Then your fine.
 

kb2vxa

Completely Banned for the Greater Good
Banned
Joined
Mar 22, 2005
Messages
6,126
Location
Point Pleasant Beach, N.J.
A dummy load will give you a 1.1:1 SWR so the acid test is a radio check, right? Oh and BTW, how do you get an SWR reading without transmitting? (;->)
 

mrweather

Member
Joined
Dec 19, 2002
Messages
913
By isolating the coax shield from the vehicle ground your coax cable is effectively becoming the counterpoise for the antenna.

The fact you saw a low SWR which means you got lucky with the length of the cable.
 

kb2vxa

Completely Banned for the Greater Good
Banned
Joined
Mar 22, 2005
Messages
6,126
Location
Point Pleasant Beach, N.J.
Not quite but the explanation of common mode current is too complicated to get into here. In any case now you see why I mentioned the dummy load, we also use the term to describe an inefficient antenna system that may look good to the meter but just won't radiate a decent signal.

"I tinkered w some stuff but never got it working right."
Being a fixed tuned antenna there is nothing to tinker with. It seems to me you assembled the mount incorrectly, placed it on one of those cheap plastic bumpers or one not electrically continuous with the vehicle frame. That's what the grounding wire is for, providing electrical continuity from the mount to the fame if there is none to begin with.

Once you have the mount assembled correctly and properly grounded look for the cause of your problem, likely the coax assembly. Check DC continuity with an ohm meter making sure both the center conductor and the shield are continuous end to end and they are not shorted together. If all else fails look to a defective antenna, it happens.
 

DX949

Completely Banned for the Greater Good
Banned
Joined
May 10, 2007
Messages
362
Not quite but the explanation of common mode current is too complicated to get into here. In any case now you see why I mentioned the dummy load, we also use the term to describe an inefficient antenna system that may look good to the meter but just won't radiate a decent signal.

"I tinkered w some stuff but never got it working right."
Being a fixed tuned antenna there is nothing to tinker with. It seems to me you assembled the mount incorrectly, placed it on one of those cheap plastic bumpers or one not electrically continuous with the vehicle frame. That's what the grounding wire is for, providing electrical continuity from the mount to the fame if there is none to begin with.

Once you have the mount assembled correctly and properly grounded look for the cause of your problem, likely the coax assembly. Check DC continuity with an ohm meter making sure both the center conductor and the shield are continuous end to end and they are not shorted together. If all else fails look to a defective antenna, it happens.
YouTube - Mr. Know-It-All: How to train your doggy
 
Status
Not open for further replies.
Top