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Old 10th Jan 2021, 12:10 pm   #1
crackle
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Default Sealine 2 Marine VHF

I wonder if anyone understands how this matrix works and can explain it to me.

Thanks
Mike
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Old 10th Jan 2021, 12:37 pm   #2
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Default Re: Sealine 2 Marine VHF

Not sure of the circuit of the device, but it looks as though you are programming the divide by N of the synthesizer.

Either a diode being in will give you a 1 value or sometimes a diode out will give a 1 value depending on if there are pull ups or pull downs to the N counter inputs.

Is the circuit easy to find, do you have a link to it?

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Old 10th Jan 2021, 12:46 pm   #3
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Default Re: Sealine 2 Marine VHF

Another quick thought on this, again not sure about the radio, but say it is a VHF marine radio that starts at 156 MHz. and the channel step is 12.5 kHz, you may just be programming the number of 12.5 kHz steps up from 156.0 MHz, so if you program one for a count of 2+4+16+32 = 54 you have 54 x 12.5KHz steps up giving 675KHz so the freq is 156.675 MHz.

The simplex or not simplex may just add a fixed offset to transmit.

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Old 10th Jan 2021, 12:46 pm   #4
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Default Re: Sealine 2 Marine VHF

It looks to be a 4-channel radio.

Guessing that a fitted diode is a logical 1

The leftmost cluster of 4 diode positions sets whether a channel is simplex. Channel 1 is, the others are presumably duplex.

The next cluster of 4 positions say that channels 2, 3, 4 are inhibited

The next one says channel 1 gets 25W

The next clusters set synth divider control bits for the 4 channels. Notice that with the exception of the 128 cluster, only channel 1 is populated in any of the other clusters. Why the 128 cluster is as it is, I don't know. Maybe it's parking the synth somewhere reasonable for fast lockup when a legitimate channel is selected?

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Old 10th Jan 2021, 12:50 pm   #5
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Default Re: Sealine 2 Marine VHF

Some VHF marine channels are designated as simplex and others as duplex. The offset is 4.6MHz with the ship's transmitter on the lower frequency.
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Old 10th Jan 2021, 3:54 pm   #6
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Default Re: Sealine 2 Marine VHF

I suspect the INH position is to reduce power output on the given channel.
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Old 10th Jan 2021, 4:09 pm   #7
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Default Re: Sealine 2 Marine VHF

Or "INH" inhibits transmit on the relevant channel(s)? From memory weren't there some marine-radio channels which were used solely for weather/navigation broadcasts by Coastguard/Met-Office? You wouldn't want ordinary users transmitting on those channels.
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Old 10th Jan 2021, 4:09 pm   #8
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Default Re: Sealine 2 Marine VHF

TX Inhibit?
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Old 10th Jan 2021, 7:07 pm   #9
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Default Re: Sealine 2 Marine VHF

Quote:
Originally Posted by G6Tanuki View Post
Or "INH" inhibits transmit on the relevant channel(s)? From memory weren't there some marine-radio channels which were used solely for weather/navigation broadcasts by Coastguard/Met-Office? You wouldn't want ordinary users transmitting on those channels.
If the channel was to be 'inhibited' then surely they would just not fit the diode matrix for that channel?

In many cases you select the transmit power from the front panel of the radio (hi/lo, 25W/1W etc)) so would have to ensure than any channel programmed that is meant to be low power can't be switched to high - hence the INH diode position.
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Old 10th Jan 2021, 7:19 pm   #10
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Default Re: Sealine 2 Marine VHF

Quote:
Originally Posted by kellys_eye View Post
Quote:
Originally Posted by G6Tanuki View Post
Or "INH" inhibits transmit on the relevant channel(s)? From memory weren't there some marine-radio channels which were used solely for weather/navigation broadcasts by Coastguard/Met-Office? You wouldn't want ordinary users transmitting on those channels.
If the channel was to be 'inhibited' then surely they would just not fit the diode matrix for that channel?.
Wouldn't that also stop it receiving?
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Old 10th Jan 2021, 7:24 pm   #11
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Default Re: Sealine 2 Marine VHF

I'm sure the marine radios I've used won't transmit on perhaps even allow selection of channel 0 (Coast Guard to lifeboats and rescue helicopters). Whether they can receive on that channel I don't recollect.

It'll be a long while before I can find out!
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Old 10th Jan 2021, 11:11 pm   #12
kellys_eye
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Default Re: Sealine 2 Marine VHF

Quote:
Originally Posted by G6Tanuki View Post
Quote:
Originally Posted by kellys_eye View Post
Quote:
Originally Posted by G6Tanuki View Post
Or "INH" inhibits transmit on the relevant channel(s)? From memory weren't there some marine-radio channels which were used solely for weather/navigation broadcasts by Coastguard/Met-Office? You wouldn't want ordinary users transmitting on those channels.
If the channel was to be 'inhibited' then surely they would just not fit the diode matrix for that channel?.
Wouldn't that also stop it receiving?
Quite.....

of course, there are weather channels and transmitting is not allowed.
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Old 12th Jan 2021, 9:58 am   #13
crackle
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Default Re: Sealine 2 Marine VHF

Its a full marine band radio. I am wondering if this matrix is to set the "private" channels such as the marina ch, and maybe Ch 0

Mike
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