VHF performance

S

SeaSpray

Active member
The last few times out with a group I have been told that my VHF output is weak and that sometimes there is clicking/static.

I have an ICOM 402 and a 4.5ft digital antenna. The Digital comes with a cable and connector attached. I added and extension cable and the AM/FM splitter.
I have tried it with the splitter removed and there was no improvement. I talked with digital and was tole I should not use the extension cable and that the barrel connector used would reduce the output by 1dB.

Today I did a test. I drove away from the boat with the handheld to see how far I could go and hear the boat VHF. I then removed the extension cable and re-did the test. It seemed like VHF was a little stronger but did not transmit any farther.

Is there any way to test the output of the radio? I have not used an SWR meter to check the antenna yet since I need to get one. Any one have any other suggestions before I buy a new radio and antenna?

Thanks,
Steve
 
Steve,

Before you spend any money on anything consider the following:
1) You say the last time out it was reported that your signal was weak and static/clicking was present. My question to you would be do you know that it was OK before the last time out?
2) You say you added an extender cable to your ant line. Was it the same type and impedance as the original coax?
3) An SWR meter will only give you a ballpark reading and I would not put to much emphasis on it unless it is higher than 2.0.
4) The radio itself should be bench checked by a reputable shop for proper output both RF and AF. Most shops can do this very easily and depending on the techs attitude at the time may or may not charge you for this simple test. (Check your power connections to the radio--DC ground is most important in marine applications)
5) Assuming the radio checks OK both RF and AF you might check your antenna installation---something may have changed. I can't see from your album where the antenna is mounted.
6) An even quicker way to accomplish a proof positive test would be to try your radio on someone elses boat and vice versa.
Best of luck to you and I suggest you do all the free checks before spending any $$$$$$$ :)
 
Certainly agree with Al. A SWR meter will be of value--both from the SWR (I would really like to see it less than 1.5:1) and it will also give the output. Most of us hams have antenna analyzers and if there is a ham nearby, you might check with him or her.

I assume that you have the radio on "HI" power output??

However, the clicking sound suggests low voltage. Check the voltage at the fuse block for the radio as you transmit. Low voltage is one of the most common causes of low output. There is the issue of corrosion, both at connectors and in the main wires, as well as possiably inadequate wiring (I put in a set of #6 wires from the house battery to the console, beside what the boats come with. (Be sure and fuse within 7" of the battery)

The antenna connector may be corroded or loose--or it was a bad fitting to begin with. I find that Digital antennas generally have a lower SWR than Shakespheare, but any of them may be as high as 3:1--so I take an antenna analyzer with me to the store, when buying an antenna.

Agree, ditch the splitter and extension--

You must be very low output in that you can notice difference as you walk away. the range should be measured in miles--not feet--so something is dramatically wrong.

Good luck finding the probelms.
 
OK, here's a few free comments. First a "digital" antenna and a plain antenna receive the same RF signal at a specific carrier frequency. Antennas are designed to transmit/receive signals over a certain frequency with a specific antenna pattern. So-called digital antennas are designed the same as other antennas. They may be better built (and for their price, let's hope so,) but they are not intrinsically different. They cover the same marine frequency and have the same pattern and the SAME GAIN.

Second the VHF signal on the marine band is analog, not a digitized signal. If you're speaking your voice is not digitized. Digital signals can be transmitted over the marine radio, as they can over any other frequency band.

Third, putting a FM splitter in the loop is a sure way to degrade your VHF signal. I'm not sure what's inside but I had to throw mine away. Everything worked great after that.

Boris
 
Thanks guys for the suggestions.

Just to clear up a few items.

I have been told by others several times over the last year that my output is low (just now at the point of wanting it fixed).

Also the radio was purchased from WM in their bargin center. Sometimes these are returns that have been repaired and sometimes stock that they are just selling off.

Yes the extension was the same cable, RG8X, as the ant cable.

The test I did today was with the boat by the house and me in the car with a handheld. I think I may have been between 4 and 5 miles as the crow flies from the boat when the signal was audile but very difficult to make out. Also the boat was not running so I don't know if part of the problem could be noise from other equipment.

This distance did not change when I removed the extension but I have re-routed the ant cable and don't need the extension.

I do know a ham and will see if I can contact him - very good suggestion.
I don't know if WM has anyone or the equipment to test a radio and the ham store I know about is an hour away.
 
I bought an SWR meter on Ebay for something like $15. It was
a new Shakespeare <forget-the-prefix>-2. The '-3' model sells
for around $100 at West. I was able to confirm my SWR (1:1) and
my power output (23 watts, I think.). Interestingly, the inexpensive
Ray Jeff I sold put out near 30. Anyhow, I doubt it matters much.
Mic quality is important, and of course bad wiring is the most
common fault as mentioned above. Heck, just holding the mic
properly and speaking at a proper volume is important.

And why do people point their antennas off at 45 degree angles?
I assume your antenna is pointing straight up? I guess those
rackish 45 deg. antennas look cool. I like my twin pair...I think
they look cool :-) (And they work).

Mike
 
Mike-

I keep my antennas tipped back to get in and out of the slip without breaking them off!

When I'm out somewhere and need good reception and broadcasting, I do stand them up to get the proper oriented signal generation.

Most of the time, however, I rake them back, as I too often have forgotten to lay them down before entering the slip when I'm busy maneuvering the boat.

The greatest chance for breaking them off is when backing out, as they jam easily on the marina roof supports.

Each "snap" is about $85-$125 or more!

Joe.
 
Boris - When i say Digital ant. i am talking about the manufacturer named Digital. You are correct the output is analog.

I did not know that SWR meters would also provide output in watts need to get one.

Don't know if I will get to work on it tomorrow or not.

Steve
 
Seabran, I assumed that that's what you meant, but I just wanted to point out that even though the brand name is "Digital" it's the same as all other (including Shakespeare, ) antennas. And they charge more.

Remember to remove the AM/FM splitter.

Boris
 
Okay - I was able to check the radio supply voltage. This is with the engine off. I start off with a supply of 13.1v when I turn on the radio it drops to 13v and when I key the mic it drops to 11.5v.

Is this a significant drop? If it is I suspect I have inadequate wiring. I ran wires from an unused switch up to the shelf - not sure what gage. The wires go to a screw type terminal block. The only other devices on that block are the cd player and satellite radio - not on for the test.

Thanks,
Steve
 
AH HA! The old low voltage gimmik! Yep, that is certainly enough to degrade the signature. As I noted most boats do not have adequate size wire. Add in each connection and switch as a potential point of increased resistance and voltage drop. I also like to wire electronics directly to a separate battery than the engine start. The voltage drop when you start the engine, plus potential spikes from the alternator are not good for the electronics. I suspect if you put in additional wiring to the battery--directly is best, your problem will be resolved--or at least considerably better.

Actually 4 to 5 miles, listening on a hand held is not bad. I am amazed at how poorly many marine VHF radios perform--and it is mostly installation.

I tend to stick to Standard Horizon or Icom for my VHF's. Ham Gear again mostly Icom, but Yaseau and Kenwood are good also.

Althought the VHF antennas are basically the same designs (half wave, 5/8 wave, some with tuned stub etc--I found that the SWR on the Digital (brand) were more consistant than Shakespheare and the quality of the wire, connections etc were a little better in the "Digital".
 
With the Icom mike it is easy to cover the little hole that receives your voice with your hand. I am used to Kenwood and Motorola mikes and was covering my Icom mike input with my hand.
This is probably not your issue, just thought I'd throw it out.
 
Thanks Bob,

Looks like I have some work to do. Do you know what #6 wires are rated for and what size fuse you used?

On my CD22 all the electronics and house power comes from a terminal block after the battery switch. So everything is powered by 1, 2, or both. I usually use just one battery while out for a few days and keep the other fresh in case of a problem. It sounds like you suggest wiring directly to one battery. Any suggestions on how to set this up for just 2 batteries?

I would like to run one set of wires to the overhead shelf to power the VHF, CD player and Sat, radio. Is there any reason I should include a switch by the helm? When the battery switch is set to Off there would be no power and when on the only draw with all radios off would be the clock on the CD player. I rarely run the entertainment while driving so only the VHF would be on.

I sure was looking forward to getting a new Standard radio with loud hailer, fog horn, big numbers, channel control on mic, ect. but I the most important thing is a good working radio.

Steve
 
You can run multiple pairs of 10 gauge forward if you do not plan to
power a large current draw item such as a windlass. I have three
pairs, one is the for original C-Dory block, one for a new electronics
block, and a spare that is not currently powered. I also ran a pair
to the port side that terminates under the aft dinette seat.

Make sure you run black (now yellow) for each positive you run
forward.

In retrospect, I probably should have run a 6 gauge forward. But,
you don't really want to run a windlass off the same wire as the
electronics, so I don't know...maybe a 6 + 10 pair?

You could run one set of power cables to the shelf, but then you would
need to intall a fuse block up there since you need to individually
fuse each electronic device. I suggest running seperate cables from
a block behind the helm. You can run the wires in split loom or some
other bundling system. I have a bunch of wires running up there, but
it all looks neat. Do not use inline fuses. If you have them, remove
them and terminate at a properly fused block.

I used 3/4" Anchor split loom inside 1" black nylon cable clamps going
up the side of the center window. The 1" cable clamps in black are
a special order and took weeks to arrive. The 3/4" split loom fit
inside the existing hole in the helm.

Mike
 
Agree with Mike, on using a fuse block. On the TC I have switches for various electronics, on the CD 25, I just runoff the fuse block. #6 is far more than you need--that is what I run for the windlass.

As to capacity of wire: it depends on the length of run--remember that the length of run is from the battery to the console and back. 12 volt circuits are rated for 3 % voltage drop (electronics) and 10% voltage drop (lighting etc)--but for 3% drop, #8 wire will do for 20 amps for the run on a C Dory! That is not a lot! Lets say you have a refigerator, the radio on transmit and a couple of lights on, or maybe the sterio!

For 10% drop, you can get by with #8 wire to about 70 amps. So with #10 (standard I believe) you can get by with about 40 amps....copper went up a lot in value last couple of years!
 
I was one of the person's monitoring and talking to Steve during the Delta trip. His transmissions were down by 3-6db (1/2-1/4) and possibly more compared to others, had to turn my volume up 1/4-1/2 turn to barely hear him.

While I agree he definitely has a wire/current problem, personally I don't see it as the cure for this problem, could be wrong, but still needs corrected. Most of the time we were running in the boats, had been for some time, even hours. His voltage should have been up to 13.5-14.5 by then. So even an abnormal voltage drop should still have been well within operating specs of the radio. Plus most of us were on 1 watt (low power) since we were within a 1/4 mile most of the time during transits.

I would look to his mic or mic circuitry within the radio. The less expensive radio's mics are wired directly into the radio though, so hard to substitute. (Steve) is that the way yours is? Otherwise, after your wiring upgrades, see if you can substitute a radio with someone, that'll at least determine antenna/wiring vs radio.

Good luck and keep at it, the radio is an extremely important piece of equipment on board.
 
Thanks for all the info guys!

Steve - On the Delta trip most of the time I was on Hi power and you still said I was low. I am not completely comfortable with the radio since I did buy it at discount.

I found that The power wires I ran from the switches unser the helm to the shelf are 18 gage. Probably way to small. I don't know the gage of the wires feeding the switches. This setup was installed by EQ and I would think that they would have selected the proper sizes.

I think I will run a new set of wires just for the radios on the shelf. I don't really know what the Sat. radio draw is but it may be several amps. I think most of the VHF's draw around 5amps transmitting on hi. And no idea what the CD player draws. Since most of the time I only have the VHF on I think I det by with 10 gage wire.

Then the test will really be to get on the water with others to provide feedback on my transmissions.

Thanks,
Steve
 
Steve, I'll make some current measurements on some of my equipment and report back. The 'receive only' radios are, usually around 0.3-0.6 amps, I'll check transmit on low and high on the VHF.

If you're going to run a new wire from the battery(s) to the helm, look at the present one and check AWG. If installed by EQ, it's probably pretty good already, 8 AWG would be excellent (except for windlass). Then just run a 12 AWG from helm common post strips (+/-) to your VHF, that'll be fine.
 
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