Vhf radio issues

I am on the bay and testing my vhf. I have an ic m11 handheld and an older unimetrics vhf . Past 23 they don't hear each other.
Unimetrics cant select international. Channel 28 is seatow radio check. I am off seaford va. I don't get a response.
Anyone have ideas about these problems

I may need a new radio. Hearing channel 16 broadcasts on icom m11 but not on old unimetrics

Try checking the antenna and its connectors. Plus you don't need to be on international for 28. But yeah, a modern VHF with DSC would be an excellent idea.

Does it receive weather channels?
If you go new, Standard Horizon GX2200 is an excellent choice.

Yes weather is perfect don't understand why it's hears the handheld on lower channels and can broadcast but not higher ones. I suppose antenna could be bad, it looks fine

I like dsc idea. What kind of gps hookup is used?

Some now have built in GPS....well worth it depending on your nav suite.

I think the fault may be the USA/international selection on one of the radios. Could be either radio at fault. Can you borrow someone elses handheld?
Old radios from the 70's and early 80's used mechanical switching in the rotating knob to set up the desired frequency which could have failed. Exactly how old is this radio? Unimetrics go way back...

I have found the Sea Tow automated radio checks offline many times.
Ch 24, 25, 26, 27, or 28 can be used depending on location. Which channel does the handheld reach Sea Tow?


The SH GX2200 has internal GPS and AIS receiver. No interface required for full function. Hookup the power, screw on the vhf coax and you are good to go. If you want the AIS to also go to your plotter, some interface is required.

High Wire said:

I think the fault may be the USA/international selection on one of the radios. Could be either radio at fault. Can you borrow someone elses handheld?
Old radios from the 70's and early 80's used mechanical switching in the rotating knob to set up the desired frequency which could have failed. Exactly how old is this radio? Unimetrics go way back...

I have found the Sea Tow automated radio checks offline many times.
Ch 24, 25, 26, 27, or 28 can be used depending on location. Which channel does the handheld reach Sea Tow?


The SH GX2200 has internal GPS and AIS receiver. No interface required for full function. Hookup the power, screw on the vhf coax and you are good to go. If you want the AIS to also go to your plotter, some interface is required.

Click to expand...

Yes, this one is from early 70's.
Has a rotating knob to select channels.
It is very very large.
It uses an old style phone handset to talk into and hear and has a privacy switch.
I know it used to work. It has been very reliable for decades.

I have this test antenna that screws on directly, and I tried it and it still did not work, so to me it rules out the antenna. Odd that it sort of works on lower number channels close to the handheld, but did not pick up any channel 16 on the water while the hand held did.

I may open it up and see if the rotary switch is dirty.
Somehow it selects frequencies, probably using electrical mechanical switch contacts.

Wish you well.

There are a few failure modes that I can think of to cause a radio to behave the way you're seeing. On a radio that old there will be crystals generating various frequencies that when used in various combinations will yield the desired channel frequency. One or more of those crystals or their circuits may have failed or the mechanical selector may have failed. It also possible that the swr is so far off that it rolls off too much at the higher frequencies.

Ken

Totally confused, now I wonder if my handheld m11 is bad.
I installed new cobra radio, and through random testing, I found 26 is the radio check for seatow, not 28.

I hear the response back on both handheld m11 and cobra radio. I do not hear me making a 26 call on the m11 handheld.
the handheld can not make a call on 26 to the new radio, I had figured it was only 5 watts was the reason, BUT i switched to low poer on 26 on the new cobra radio, and seato radio check works fine.
when I call on the new radio on channel 26, I dont hear it on the m11, but I do hear the response back frim seatow radio check.
any ideas?

Maybe my very old unimetrics radio is actually ok. Now I need to bring it back out here and retest it. I do have a SDR dongle, I can test it on the PC at the house and see if its broadcasting.
I know the antenna is good since it works fine with the new cobra radio.

for instance, if I key the cobra on 20, the hadheld m11 has no response.
If I do it on 20a, the handheld m11 responds.

Only use the”a” version of a channel in the US. Channel 20 transmits on one frequency and receives on another. 20A is not the same. If you look at the channel chart in the cobra manual you can see the difference. Try a channel like 09. All of your radios should work on 09, 68, 72

High Wire said:

Only use the”a” version of a channel in the US. Channel 20 transmits on one frequency and receives on another. 20A is not the same. If you look at the channel chart in the cobra manual you can see the difference. Try a channel like 09. All of your radios should work on 09, 68, 72

Click to expand...

Thanks, feeling dumb now, I used to know that, but I forget what I almost never use.

High Wire said:

Wish you well.

Click to expand...

With the Viking Funeral....

sdowney717 said:

I am on the bay and testing my vhf. I have an ic m11 handheld and an older unimetrics vhf . Past 23 they don't hear each other.
Unimetrics cant select international. Channel 28 is seatow radio check. I am off seaford va. I don't get a response.
Anyone have ideas about these problems

Click to expand...

Check the PL-259 connector

You are aware, are you not, that there is quite a bit less power transmitted from your handheld than from your installed VHF? I certainly would not expect a response from an automated radio from a handheld unless I was on top of it.