improving radio reception

colobear · Posted: Thu May 03, 2012 12:52 am Post subject: improving radio reception

I have been dissatisfied with my VHF reception for some time. I get a lot of very broken transmissions from powerful stations, i.e. Coast Guard, that should be crystal clear. This happens in different weather conditions, at various times of day and in different locations. It is as though the squelch is being turned up and down rapidly and the transmission is very broken with only every third word or so clear. My radio is a Standard Horizon Matrix 2100 connected via about 20' of RG8X marine coax cable to a Shakespeare 5400XP 3db 4' antenna. All of these are good products and I see no visible indications of damage. I don't have an SWR meter so cannot check losses directly. I am debating whether to upgrade the antenna to a 6db 8' and switching to RG213 or LMR400 coax. Any hams or other knowledgeable folks out there, help please. Should I make the switch to 6db, what is a good high quality VHF antenna?

Thanks.

doc · Posted: Thu May 03, 2012 1:23 am Post subject: Radio reception

Most likely a bad antenna connector. Radio is only as good as the antenna and it's connections. 20' sounds like a lot of wire on a CD but should still work fine if the wires and connectors are good. Try cutting back your wire and getting a good install on your connectors and see how that works out. Could still be the radio but less likely.

doc · Posted: Thu May 03, 2012 1:26 am Post subject: Radio reception.

Oh yeah. Switching to a 6ddb antenna will probably help.

hardee · Posted: Thu May 03, 2012 1:33 am Post subject:

Barry, it sounds like you have good equipment. Unless it is the antenna, switching to a 8', 6db gain will not improve a periodic loss of audio output. Does the intermittent lapse happen when on the move, or does it happen with everything perfectly still? Like locked down tight. Even the mic and cord not moving a millimeter. I know you are saying reception so that is what I am asking about. Antenna absolutely rock solid. If it is still happening in these cases then it may be a component issue. One of the first places for intermittent issues to show up is in the mic cord, just out from the plug, at the end of the stress relief or so. Even though the transmit light is not coming on, the motion there can cause the receive to blank out in preparation for transmitting.

It could also be in the squelch system itself. But more likely a connection somewhere. Tough to track down. Do you have a handheld that you could plug in to your antenna system at the base VHF end to see if it still acts up, or if the problem goes away on the portable? Might help sort out at least one end of the game.

An other point would be to switch mics out and see of the issue follows or not. Could probably do that at FH too. My 2150 might be a compatible switch taht we could do there at the same time, obviously only changing one peace at a time.

I have an SWR meter you are welcome to use. I could bring it to Friday Harbor if you don't get something before then.

If that antenna is new with the boat (2006) sometimes the connection at the base can go south. (Dang antennas get old too, one day at a time.) That would be something that can be checked with everything rock solid, and then if all is working, take the antenna nad wiggle it. Sometimes the antenna will twist on the bottom and you can try doing that to see if your intermittent comes back.

Hope that helps some.

Harvey
SleepyC Moon

tpbrady · Posted: Thu May 03, 2012 1:53 am Post subject:

The most likely cause of the problem is a connector. I just swapped a Shakespear 8 ft 6 dB antenna with some cable issues for a Digital 8 foot 6 db antenna connected to my Standard Horizon Matrix 2150. I am running that on the radar arch where I also have a 4 foot GAM stainless steel whip connected to an ICOM. I really can't tell much difference between the GAM and the Digital antenna so far. I have always been impressed with the GAM but its main limitation is on the transmit side as 3 dB gain antenna. I like the Digital because it eliminates the connector from the equation as it uses a mini-UHF connector that adapts to a PL259 to attach to the radio. The mini-UHF will pass through the arch and can be routed directly to the radio.

Dreamer · Posted: Thu May 03, 2012 2:26 am Post subject:

Barry,

I'll bring my SWR meter to Friday Harbor.

Barry Rietz · Posted: Thu May 03, 2012 5:12 am Post subject: Radio Reception

Barry, The majority of maritime radio problems involve transmission line issues. I would suggest checking the "resistance" using an ohmmeter first with each end disconnected. If they are within tolerance you might also want to check continuity to make certain the connectors are not "open". As you are performing the tests, include doing it while "wiggling" the connectors.
You mentioned the problem occurred during weather conditions. Salt water intrusion could also pose problems. If the tests do not show faults, you might consider taking the radio to an electronics repair facility and have the receiver's "front end" checked out. If you were ever in close proximity to a high output station, several of the solid state attenuation devices could have been fried! Good luck!

colobear · Posted: Thu May 03, 2012 12:39 pm Post subject:

Thanks all,

I'll start with the connectors and work my way through the system. I may still go to an 8' 6db and use the existing 3db for an AIS antenna but won't do anything until I have isolated the problem.

I appreciate the advice and offers of help.

hardee · Posted: Fri May 04, 2012 2:30 am Post subject:

Barry, My 3 ft SS whip is set up with the Standard Horizon 2150 using that antenna for both VHF and AIS reception. The RayMarine 218 is set up to share an antenna splitter with the VFH and an AM-FM stereo radio. Both work fine.

Harvey
SleepyC Moon