Radio performance

[localboy]

Looking for input from you that are very experienced, like Dr Bob.

Yesterday we were out returning from Poulsbo, heading to Everett. We were hearing VHF transmissions from boaters in Port Townsend, Deception Pass and even one boater calling in to John Wayne Marina (Sequim). These were clear transmissions. Yet we had very lousy reception from someone just outside Clinton and others in the Everett area? Radios were set on "high power" setting (25 watts) at the time.

Why is this?

[jkidd]

Most of the performance is going to be based on the antenna. How well it's made as well as the connections on the cable. How well it is positioned and how high you can get it. There are a lot of factors in play such as interference from other antennas, bad ground planes and bad cabling that will have a lot to due with how far you can transmit.

[JamesTXSD]

Likely, it isn't your radio. If someone is using low power or has a crap radio or antenna, it is going to show up in their transmissions. The fact that you were getting some transmissions decent and others not, sounds like their issue.

[ssobol]

[Micahbigsur@msn.com]

Sometimes you can get a distant skip in certain conditions even with VHF, occasionally we have heard mainland Mexico from Baja 85 miles away over the sea.

[dotnmarty]

At sea in the Atlantic we could always get "WCKY , Cincinnati 1, Ohio",all the way to Ireland (Just an irrelevant memory).

[gulfcoast john]

Agree the most likely culprit is the antenna rather than the radio. They lead a hard life.
Or maybe the distant boaters were transmitting at 25w (fixed base max power) and the closer ones were on handhelds (5w max but dialed down to 1w for close marina contact, which is appropriate).

Localboy, clean your contacts and then use your handheld VHF on 68 or 71 on low power to call your fixed mount radio from a few boat lengths away.
Alternatively, a better equipped Brat than me (like Colby or Bob) will have a VHF signal meter to check your antenna (and Colby didn't charge me anything, that's just the kind of guy he is).
You'll figure it out.

Best!
John

[BrentB]

Antenna brand, model and length?

[hardee]

Mark, as noted, and you probably already know this, but having you VHF on high power only affects your transmitting power, not any recieving performance. Also, some VHF radios will automatically drop the power from High to Low (1 watt) depending on your channel selection (going to 13 or 66 for instance.)

There is a VHF station on 28 in Friday Harbor the you can call and it will record your transmission, then play it back to you. You get time to say your call name and location and that is about all, but it is worth itto get the playback. (There is provision for this type of service all around the country, but that is the only one I know of.)

Hearing someone calling in to John Wayne is interesting. 1. They do not monitor any VHF. 2. It must have been on a high power channel. 3. I would also bet it was a sail boat with a high mast mounted antenna. 4. They were out near the Point Wilson/Smith Island area. Those are all based on the fact there is a considerable land mass with some height between you and where they would likely be. The other calls, PT and Deception Pass could (probably are) all line of sight calls and on high power (from the transmitting vhf) are not really out of the ordinary.

The best you can do, again as mentioned, clean your coax conections, check for any corrosion, check your antenna for any damage or wear spots and do the handheld check, maybe from a block away. Or start close and move away as the signal allows.

Harvey
SleepyC

[thataway]

Marine VHF (in the 150 Mhz range) is basically slightly more than "Line of sight". Yes, antenna design, condition, (including corrosion) can make a difference. Definitely the higher antenna on top of a 60 foot sailboat mast will be heard further than a C Dory 8 feet off the water.

Micahbigsur@msn.com. Touched on a phenomenon termed "Tropospheric ducting". There is even a weekly forecast: for VHF, UHF ducting



The Troposphere is the lowest region of the atmosphere, extending from the earth's surface to a height of about 3.7–6.2 miles , which is the lower boundary of the stratosphere. This is where most of our weather is formed. A temperature inversion (warmer weather aloft) will cause an increase in a higher refractive index in the Troposphere, and the effect can propagate VHF signals up to 1000 miles. We routinely can hear and at times communicate with St. Pete CG sector during the summer months a distance of about 300 miles.

We were several hundred miles at sea, and heard a U S warship calling the pleasure yacht " XX miles off their Starboard bow". We didn't see any ship on radar or visual..waited--a second call. We responded that we didn't see the Navy Ship--and asked their position. The Navy ship was 385 miles away--with clear two way communication.

[localboy]

Thanks for all your responses. Yes, I know that the transmit power is just that, transmit. I was trying to provide any/all info. Obviously, I left the below out.

[localboy]

[BrentB]

Nice radio setupu

[thataway]

WCKY is a 50,000 watt clear channel AM (1530kHz) station--it only competes with a sister station in Sacramento CA. After Dark ( in Sacramento) WCKY switches to a directional antenna, so as not to interfere with KFBK Sacramento. The AM proportion is far different than the VHF--and under the right conditions can be heard world wide. Not sure how many remember Del Rio Texas (actually across the River in Mexico: XER and XERA.(1570kHz) At one time blasting one million watts over the entire USA--it was the one radio station I could be assured of getting when driving from S. Calif. to Houston TX in the late 50's. The AM broadcast band, will follow the contours of the earth and bounce off the ionosphere--so under the right conditions can be world wide.

As for the Sequim broad cast--if in the harbor it was a form of ducting--bouncing over the hills.

The close boat could have been in an area with high electrical noise--(QRM--or man made electrical disturbance). If real close potential of front end of the radio overloading--but most marine VHF are protected from that. CG could have had better filtering equipment. The latest commercial and ham radios have some very sophisticated and narrow filters, so you can filter out interference.

The best test for your radio is to see how other boats read your transmissions. That tests not only power, but distortion and modulation.

[hardee]