Fringe VHF Marine Reception Help Needed

[MDScanFan]

Lol, amateur move...yesterday I realized I have the attic mounted yagi pointing in the wrong direction. I am pointing it 45 degrees away from the intended direction. That could account for 2-3 dB or loss based on the ~90 deg beam width of the antenna. I will make that adjustment over the weekend and see how much it helps.

Regarding the Sirio 6 element yagi they have two versions available: 140-160 and 155-175. I would use it for marine primarily and also rail. So 156-162 MHz and everything else is a do not care. Is their lower frequency option better for me given the higher gain for the frequencies I care about? They do not report gain above 160 MHz but the match looks great up to 165 MHz. I am thinking the gain would likely hold up well to 162 MHz. What do you think?

Datasheet

 

[prcguy]

Gain on a Yagi drops off rapidly above a certain spot so its hard to tell how it will work unless you thoroughly test it. I bought the 140 to 160MHz version for amateur and some Govt stuff and if you will never do amateur then get the higher freq version for marine.

Lol, amateur move...yesterday I realized I have the attic mounted yagi pointing in the wrong direction. I am pointing it 45 degrees away from the intended direction. That could account for 2-3 dB or loss based on the ~90 deg beam width of the antenna. I will make that adjustment over the weekend and see how much it helps.

Regarding the Sirio 6 element yagi they have two versions available: 140-160 and 155-175. I would use it for marine primarily and also rail. So 156-162 MHz and everything else is a do not care. Is their lower frequency option better for me given the higher gain for the frequencies I care about? They do not report gain above 160 MHz but the match looks great up to 165 MHz. I am thinking the gain would likely hold up well to 162 MHz. What do you think?

Datasheet

 

[MDScanFan]

OP back with an update regarding the radio I am using...I mentioned earlier that I started with an old 2M RS mobile and switched to an Icom marine radio (IC-M127). While it was fun to add a marine radio to my setup, and it did show improvement vs the scanners and 2m radio (ex: sensitivity and overload), it still exhibited intermod issues across the marine band. With a PAR 152 notch filter the issue clears up appreciably but not completely. If I add a PAR 162 notch the issue goes away completely. I can’t recall the exact loss I measured but it probably around 2-3 dB. These filters are located between a preamp and the radio so their loss is not too critical.

I had great success using a Kenwood 281A for my rail setup and I just bought another one to replace the Icom marine radio. Filters are no longer needed, it is more sensitive, and the audio clarity is better. I highly recommend the 281A to others in a similar situation.

 

[cmdrwill]

The Kwoodie TM281 is a great radio. Only thing I and others do not like is the mini speaker, hi pitched screechy audio.

Was looking at putting some roll off in the audio to reduce the high frequencies in that tiny speaker.

 

[WB9YBM]

The Kwoodie TM281 is a great radio. Only thing I and others do not like is the mini speaker, hi pitched screechy audio.

Was looking at putting some roll off in the audio to reduce the high frequencies in that tiny speaker.

Common problem since manufacturers started shrinking radios back in the 1980s. A spare speaker plugged into the "EXT SPKR" jack & laid on top of an empty Kleenex box (the box acting as a baffle) works wonders (cheap solution) or (slightly better solution) a rear deck speaker used in car stereos works pretty well, too....

 

[majoco]

I assume (careful!) that you are still using the antenna in the attic space. Instead of getting more and more expensive coax, why not try putting the radio right next to the antenna and running audio coax down to an audio amplifier at your listening station - of course a feed of 12volts will be necessary unless you have power up there too. Even better if the radio is capable of being remote controlled via a USB cable or similar.