VHF problems - Where to start?

[Dave in Mpls]

I have an Apelco 8500 VHF coupled with a 8' Shakespear Galaxy antenna. The problem is, I seem to be able to transmit only intermitantly. I can establish contact with someone 20 miles away, and then try again when I'm about 5 miles away or less, and they can't hear me or can only hear parts of my transmission.

Does this sound like a radio problem (bad PTT button or something), an antenna problem, or a PL 259 connection problem? I am currently using one of the Shakespear Centerpin PL 259 connectors with do not require any soldering. I know I should go with the PL 259 which requires soldering in place, but my soldering skills leave a little to be desired! I seem to be able to receive just fine.

Thanks for any ideas!

Regards

[RANGER]

Dave,

There are a number of possible solutions for you, I had the same problem, initially:

1) Make sure you are wired directly to your battery, not a distribution buss and not a fuse panel. Use the in-line fuse.

2) I'd get someone to solder the PL 259 if you feel it is not your best skill. That connection would do this to you.

3) Exercise your mic off line. By this I mean close and open the key 30 or 40 times in rapid succession. This can clear dirty contacts and something called "follow" which is the sweep of the contacts after they have made the connection (don't worry about it - it's an electrical thing)! If you feel you can do this - open the mic and clean the contacts with alcohol (90+%) and a Q-Tip and some very fine emery paper, 400+ grit.

4) Check your connections throughout the setup for anything that is loose.

I think the A-#1 problem is most likely the battery connection. I had the exact same failure with my Apelco and this cleared it.

Hope this works!


RANGER


"KEEP YOUR LINES WET, YOUR POWDER DRY and THE BEER COLD"!

[Dave in Mpls]

Thanks for the ideas, Ranger.

The radio is wired directly to one of two batteries wired in parallel in the rear of the boat for starting/electronics. I will definately double-check the connection, however. This all seemed to start after getting caught out on Mille Lacs in a downpour about a month ago or so. I'm sure the mic got wet, even though the radio is stored in an electronics locker. I'm not to worried about the problem, as everything is still under warrenty. I just want to know the radio is going to work if I REALLY need it!

Anyone in the Mpls area know a thing or two about soldering and PL 259 connections...Hans? Kaz?

Regards

[RANGER]

Dave,

Now that you said it started after getting caught in a storm, I'd concentrate on the mic and the PL but still check the items I previously listed. I know it is "another" expense but you may want to consider an SWR meter for VHF, like the ones for CBs. I have one for the CBs and the VHF. If I was closer I'd run over with it to check the system. I'm betting it is the mic! You haven't blown your "finals" because you can get out from time to time! I'm betting it's the mic and you'll need a new one! ;-)


RANGER


"KEEP YOUR LINES WET, YOUR POWDER DRY and THE BEER COLD"!

[RANGER]

You know? It could be that the battery connections became corroded from the rain. Take them off and clean them, too!


RANGER


"KEEP YOUR LINES WET, YOUR POWDER DRY and THE BEER COLD"!

[war-n-peace]

Ranger:

How do you go about adjusting the SWR on a VHF? Is there a way to change antenna length like a CB and does VHF use the same type of signal pattern ?

Bill W.

[KAZ]

Dave: Give me a call 763 553 1000. I have the test equipt to see whats wrong...Kaz

[RANGER]

war-n-peace,

To answer your questions:

1) If you find your antenna is out-of-tune you need to insert a "tuning box" in series with the antenna. Once installed you can then dial in capacitance and/or resistance to bring the antenna length in line with the wavelength. Actually, you are virtually (love that word) adjusting the antenna length via electronics. Unlike CBs, you can't easily cut or physically adjust VHF antennas. Also, unlike CB antennas, VHF antennas are more closely monitored by the manufacturers' for quality, then are CB antennas. VHF antennas are factory tuned.

2) VHF signal patterns are more directional then are CB's which broadcast in, more or less, a radiant circle with the antenna in the center. VHF, on the other hand, are eliptical and controlled by the Gain in the antenna, i.e. a 3 Db gain broadcasts a pattern similar to a basketball, front and rear (like putting two basketballs together, where they touch is where the antenna is). 6 Db gain broadcasts a signal resembling a cucumber, greater distance, narrower beam.

With VHF, broadcast RANGE is directly related to antenna height rather then any other factor. The higher the antenna, the greater the range, period. VHF is line-of-sight broadcast.


RANGER


"KEEP YOUR LINES WET, YOUR POWDER DRY and THE BEER COLD"!

[Kaz]

Dave: I will be in town only until Wed noon. I will be back Mon AM. E mail me your phone number if you don't get me before then. (ddkaitz@qwest.net) Heading to LOW to fish. Kaz (Dick Kaitz)