Thanks, no, no way to tune as far as i can tell from brochure and data sheet. The antenna base was one big sealed unit. I dont remember seeing anything like that and no mention of it in the sparse documentation.
This is good to know. I may need to resort to one of those type of connectors at the masthead. I just hope I can pull enough slack cable to redo the end connector at the mast head. Thats my biggest worry. I dont think that LMR is going to budge. Its in a narrow conduit with another 12gauge wire going to the mast top. May need to lower the antenna and mount it a little lower.
No, no dummy load. I should probably get one but dont really understand how they work yet.
They are just a resistor that absorbs the energy and allows the radio to transmit at power like it sees a perfect antenna on the end. So you just plug it in to any connector to test the system up to that part (with the meter in line, of course). If things improve, then the problem is downstream of wherever you plugged in the dummy load, so you just keep moving it down system until you find the problem.
This type of tuning mechanism would be very rare on a marine VHF band antenna. I've never seen one outside of automobile types. They generally come tuned to 1/2 or 5/8 or 1/4 wavelength at 156MHz as end fed or dipole or colinear array. Some whips have a removable whip that could be trimmed by cutting, but there is rarely a reason for doing this.
That link sent me to a general google search with a lot of results discussing CB and automobile antennas. The AI chatbot result at the top talked about adjusting a "marine" antenna, but all of the citations it used were for CB antennas.
OK. Now go and find an example one of these adjustable marine VHF antennas. I've searched and cannot outside of one or two portable automotive mounted versions, and these were made to cover the entire 2M band for mobile ham operation. The fact that they can also be tuned to marine frequencies within the 2M band is just emergent from those frequencies being within the 2M band. While that Cobra article describes a theoretical approach, it needs to be noted that none of Cobra's marine VHF antennas are adjustable in this manner. Cobra is also much larger in terrestrial and ham than in marine.Since my posting I discovered that there are marine antennas that are not adjustable and other marine antennas that are adjustable.
The link I provided the first line indicates a marine antenna SRW meter and if you continue reading you will find where it talks about how to adjust the length of the whip with the set screw. I would not cut the antenna.
Here is that link
Marine Radio SWR
What is SWR? SWR is short for STANDING WAVE RATIO. It is a measure of how well the antenna is performing. Most problems with the antenna or antenna cable will show up during an SWR check. Please note that the SWR is a measure of antenna perfo...support.cobra.com
