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Author Topic: Mystery transceiver: SEA 104 HF maritime radiotelephone?  (Read 2345 times)
KI6EFA
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« on: February 26, 2014, 01:39:27 PM »

Howdy, all. I'm trying to find more information about a Stephens Engineering Associates SEA 104 radiotelephone. I have no information on where it was, other than a callsign and "Lucrezia" (presumably the name of the boat) on a Dymo label on the top.

I contacted SEA, and they had no information or documentation on it, other than that it was produced in the late 1970s or early 1980s.

I was able to find some information on another SEA product, a 200-series radiotelephone, and found that it was programmed by burning EPROMs.

Judging by the pre-printed label with various maritime radio channels on the faceplate, I'm wondering if this is programmed via crystals or EPROMs, and whether I'd be able to adapt it to amateur use by reprogramming it. If so, it might finally spur me to upgrade to General!

Any information, documentation, or manuals on this or any related radios would be awesome.

Images (click for full-size):




I don't have any photos of the inside, but I will have access to it again on Friday, and will open it up then.
« Last Edit: February 26, 2014, 01:48:21 PM by KI6EFA » Logged
G3RZP
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« Reply #1 on: February 26, 2014, 01:47:14 PM »

It will be USB on SSB and USB+carrier on AM. Obviously needs an external antenna tuner. It's not apparent if it can send a radio telephone alarm signal (a tone warbling between 2200 and 1300 Hz every 500ms or so for 1 minute, used when in distress). Mean to cover (probably) 1.6 to 3.8MHz and the 4, 8 and maybe 12 and 16 MHz marine bands.

Likely to have good crystal filters, and if meant for duplex, one for tx and one for rx.
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KI6EFA
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« Reply #2 on: February 26, 2014, 01:50:01 PM »

It will be USB on SSB and USB+carrier on AM. Obviously needs an external antenna tuner. It's not apparent if it can send a radio telephone alarm signal (a tone warbling between 2200 and 1300 Hz every 500ms or so for 1 minute, used when in distress). Mean to cover (probably) 1.6 to 3.8MHz and the 4, 8 and maybe 12 and 16 MHz marine bands.

Likely to have good crystal filters, and if meant for duplex, one for tx and one for rx.

I fixed the images; if you click on the front one, you can read the frequency/callsign channels on the front. Do you know what the deal is with the ones labeled "417", etc. instead of the exact frequency? Would that just be 4.17 mhz?

The "antenna coupler" socket is somewhat confusing to me; I suppose it'd probably be for triggering an antenna switch when you change channels, to avoid having to re-tune.
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N7BMW
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« Reply #3 on: February 26, 2014, 03:33:23 PM »

Those numbers are the marine SSB channel designations.  If you google "marine SSB frequencies" you will be able to find a table of the frequency & channel numbers.  Basically the first one or two digits designates the Mhz band,  ie 201 is in the 2 Mhz band and 1601 in 16Mhz.  The split frequency numbers were for radio channels used for telephone calls - AT&T High Seas service and others.  AT&T dropped their service over a decade ago but WLO in Mobile, Alabama is still operating.

What you have is a crystal controlled marine SSB transceiver.  I have an SEA 222 transceiver on my boat.  It is from the mid 1980s.  IMO not much of a radio.  I remember seeing these old radios stacked up like cordwood at a marine electronics dealer in the Caribbean about 20 years ago.  As soon a synthesized radios were developed no one wanted the limited channel crystal controlled ones.

It's only value is the fun you can have playing with it.

73,
Brian
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W9GB
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« Reply #4 on: February 26, 2014, 04:09:20 PM »

Your SEA 104 is likely a Crystal Controlled MF/HF SSB transceiver.

ITU RadioTelephone Channels (Place a telephone call from ship at sea).
http://www.naval.com/hf-freq.htm

KMI is Inverness, California
Channel 417; Ship Tx: 4,113 kHz; Ship Rx: 4,405 kHz
That service operation shut down in October 16, 1999.
==
Do Not "Test" that SEA Radio on Channel 1, which is marked as: 2,182 kHz (above 160 meter amateur allocation).

The radio frequency of 2182 kHz (kilohertz) is the international calling and distress frequency for maritime radiotelephone communications on the marine MF bands.  Read about it here:
http://en.wikipedia.org/wiki/2182_kHz
« Last Edit: February 26, 2014, 04:23:49 PM by W9GB » Logged
KI6EFA
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« Reply #5 on: February 26, 2014, 06:49:48 PM »

KMI is Inverness, California
Channel 417; Ship Tx: 4,113 kHz; Ship Rx: 4,405 kHz
That service operation shut down in October 16, 1999.

KMI, you say? Smiley


KMI receive site by atomicthumbs, on Flickr
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N7BMW
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« Reply #6 on: February 26, 2014, 08:10:31 PM »


Do Not "Test" that SEA Radio on Channel 1, which is marked as: 2,182 kHz (above 160 meter amateur allocation).

The radio frequency of 2182 kHz (kilohertz) is the international calling and distress frequency for maritime radiotelephone communications on the marine MF bands.  Read about it here:
http://en.wikipedia.org/wiki/2182_kHz

2182 is no longer monitored by the USCG, probably not by anyone else either.  Do not test this radio on any of the frequencies.  They require a ships station radio license.  None of those frequencies lie within the amateur radio bands.
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KI6EFA
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« Reply #7 on: February 27, 2014, 11:46:32 AM »

don't worry, I'm only a Technician so I won't be testing it with anything that's not a dummy load Smiley
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