VHF radio problem

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gregorybross

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Jan 31, 2012
56
Catalina 30 mkIII Santa Barbara
Hello All-
I installed a new VHF radio, Standard Horizon GX 2150, and I now send a high pitch sound when transmitting at 25 watts. The sound does not occur at 1 watt transmission. I did add about 2 feet to the antenna coaxial cable using a shakespeare gold connector. The radio does not have the problem when I use a small emergency antenna. Any ideas?

Greg
 
C

Chief RA

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Nov 26, 2012
2,315
Catalina 250 Bodega Bay CA
Email standard horizon and ask them. Sounds like the coax ext. is the culprit. We tend to cause most of our own problems. Same size coax? Gold connectors are waste of good money! Chief
 
Don S/V ILLusion

Don S/V ILLusion

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Sep 25, 2008
7,523
Alden 50 Sarasota, Florida
Could be a ground loop but more likely RF feedback either in the wiring or the coax. How is it grounded and is it a resonant length coax or ground?
 
G

gregorybross

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Jan 31, 2012
56
Catalina 30 mkIII Santa Barbara
The new VHF is grounded with the same ground wire the old one used. I goes to the ground bus in the main panel. Juan at Standard Horizon also thinks it is RF feed back. The spliced coax is the same. I guess I need to remount the radio without the connecter or pull all new coax from the top of the mast. ugh.
Greg
 
C

Chief RA

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Nov 26, 2012
2,315
Catalina 250 Bodega Bay CA
Try short coax with connectors instead of a splice. Coax does not respond to splicing well and can cause impedance problems. Chief,EE,IE, FCC lic#1890
 
F

Forrest15112

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Jan 22, 2008
423
Catalina 30 Mandeville, La.
Greg, all good advice from posters. When you say "splice", i picture proper connectors attaching two cables. This is fine at vhf, but if you have the coax stripped back and twisted, soldered, etc, this would almost certainly be your problem.

You said you used a Shakespeare gold connector. Hopefully, it's not one of those "no special tools required" types that clamp on the cable. Those are way overpriced and should only be used in an emergency. Definitely don't install one on the mast unless you like going up and changing it. A cheap crimping tool for most common cables can be had for as low as $25 and will do a good job on the connectors. I use crimp on connectors whenever possible because they're quicker, cleaner, and just as good as the best soldered connectors.

Good luck with the repair.
 
Don S/V ILLusion

Don S/V ILLusion

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Sep 25, 2008
7,523
Alden 50 Sarasota, Florida
gregorybross said:
The new VHF is grounded with the same ground wire the old one used. I goes to the ground bus in the main panel. Juan at Standard Horizon also thinks it is RF feed back. The spliced coax is the same. I guess I need to remount the radio without the connecter or pull all new coax from the top of the mast. ugh.
Greg
Click to expand
If RF feedback with the new radio, don't make any snap judgment about the coax being the problem particularly when it is the most difficult source. Always try the easy stuff first. By that, I mean the feedback can often be caused by RF getting into the microphone cable, even shielded cable.

There are two ways to eliminate the mic cable. One being to install a snap-on ferrite choke available online, Radio Shack or other electronics supplier. The other alternative is to knot up the cable tightly so as to change the electrical length. The latter May or may not suffice depending on the severity of the feedback.

I'd do the above first before resorting to the onerous task of replacing the coax which you can do a quick and dirty test on with an SWR meter.
 
C

Chief RA

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Nov 26, 2012
2,315
Catalina 250 Bodega Bay CA
Good advice Don, I was just trying to get him to undo what problem he might have created first and then to the RF filter concept next . There is a good chance that the extension in some way caused the RF problem. We still do not know if he spliced or coupled the extension, plus is the center cable pin in the end connector bent over, wrong RG cable size, radio location, etc. Don, he could use the old trick of wrapping his mic cable, RF cable with tinfoil to see if he really needs to buy a filter? Chief
 
G

gregorybross

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Jan 31, 2012
56
Catalina 30 mkIII Santa Barbara
Thanks guys. I did use a coupler not a splice. I think this might be the problem. I will properly splice the extension with crimp on connectors. If that does not solve the problem I will try the shielding the mic cable.
Greg
 
C

Chief RA

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Nov 26, 2012
2,315
Catalina 250 Bodega Bay CA
Actually a splice is attaching 2 cables/wires together without a coupler. It usually is accomplished by soldering. You really need to know your stuff to splice braid. Please let us know what works. Chief
 
G

gregorybross

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Jan 31, 2012
56
Catalina 30 mkIII Santa Barbara
Chief-
I finally got around to addressing my RA feedback problem. I soldered a push on connector to each end and connected it with a push on coupling. I could not find crimp on connectors at my local West Marine. This has solved the problem. I found it difficult to find connectors for marine grade RG8 coax.
Glad it's fixed. Thanks for all your help.
Greg
 
C

Chief RA

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Nov 26, 2012
2,315
Catalina 250 Bodega Bay CA
Thanks for feedback to us, glad it worked and have a Happy Holidays! Chief
 
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