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Default SEA 112 radio advice / manual / schematic needed

Hello,

I've got one Stephens Engineering Associates SEA 112 HF marine
transceiver..

Yes, it's a crusty old radio, but I'd like to fix it up. I do repair
radios from time to time, but I'm not familiar with this design at all.

1. How are the frequencies programmed in? I see no crystals or diode
matrix for programming the channels as I would expect in an older set. I
have not taken the sandwich of boards in the center of the radio apart..
the bandswitch seems to go through there and I'm not going to mess with
it just yet. So, is this an EPROM-programmed set?

2. Has anyone managed to convert this model for ham radio use or is it
best left as is? (I've read at least one case of a mariner throwing one
away, so they must not be too valuable..) I've got no antenna tuner,
just the set with microphone.

If anyone has the manual including schematic/service data, I might have
an interest in it.

Thank you,
Patrick


If you would like to reply directly, please reply to the e-mail address,
removing the "REMOVE_THIS".


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Default SEA 112 radio advice / manual / schematic needed

patrick jankowiak wrote in news:Q4Nvj.7445$Ru4.5658
@newssvr19.news.prodigy.net:

I've read at least one case of a mariner throwing one
away, so they must not be too valuable..)


That's pretty good advise.....as good as any you'll get here.

Be informed marine radios can ONLY be repaired by holders of the FCC's
appropriate technician's license, not just any old boy on the dock.

http://wireless.fcc.gov/commoperators/

Radio Maintenance and Repair

You need a commercial radio operator license to repair and maintain the
following:

* All ship radio and radar stations.

* All coast stations.

* All hand carried units used to communicate with ships and coast
stations on marine frequencies.

* All aircraft stations and aeronautical ground stations including
hand-carried portable units) used to communicate with aircraft.

* International fixed public radiotelephone and radiotelegraph
stations.

You do NOT need a commercial radio operator license to operate, repair,
or maintain any of the following types of stations:

* Two-way land mobile radio equipment, such as that used by police
and fire departments, taxicabs and truckers, businesses and industries,
ambulances and rescue squads, local, state, and federal government
agencies.

* Personal radio equipment used in the Citizens Band, Radio Control,
and General Mobile Radio Services (GMRS).

* Auxiliary broadcast stations, such as remote pickup stations.

* Domestic public fixed and mobile radio systems, such as mobile
telephone systems, cellular systems, rural radio systems, point-to-point
microwave systems, multipoint distribution systems, etc.

* Stations that operate in the Cable Television Relay Service.

* Satellite stations, both uplink and downlink of all types.

NOTE: Possession of a commercial radio operator license or permit does
not authorize an individual to operate amateur or GMRS radio stations.
Only a person holding an amateur or GMRS radio operator license may
operate an amateur or GMRS radio station.

................just for information, of course.....Pay no attention.....

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First recorded activity by BoatBanter: Dec 2007
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Default SEA 112 radio advice / manual / schematic needed

In article ,
patrick jankowiak wrote:

Hello,

I've got one Stephens Engineering Associates SEA 112 HF marine
transceiver..

Yes, it's a crusty old radio, but I'd like to fix it up. I do repair
radios from time to time, but I'm not familiar with this design at all.

1. How are the frequencies programmed in? I see no crystals or diode
matrix for programming the channels as I would expect in an older set. I
have not taken the sandwich of boards in the center of the radio apart..
the bandswitch seems to go through there and I'm not going to mess with
it just yet. So, is this an EPROM-programmed set?

2. Has anyone managed to convert this model for ham radio use or is it
best left as is? (I've read at least one case of a mariner throwing one
away, so they must not be too valuable..) I've got no antenna tuner,
just the set with microphone.

If anyone has the manual including schematic/service data, I might have
an interest in it.

Thank you,
Patrick


If you would like to reply directly, please reply to the e-mail address,
removing the "REMOVE_THIS".


See my post to the other post you made on another group.

--
Bruce in alaska
add path after fast to reply
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First recorded activity by BoatBanter: Jul 2006
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Default SEA 112 radio advice / manual / schematic needed

On Feb 22, 11:14*pm, patrick jankowiak wrote:
1. How are the frequencies programmed in? I see no crystals or diode
matrix for programming the channels as I would expect in an older set.


It uses eprom programming. It's been a while since Iv'e worked on
one of these but I have a service manual and have reprogrammed these
radio's. As I recall, it's kind of weird how it's done, but you'll
need a basic eprom programmer. I can dig out my notes and give you the
details on programming. Don't remember off the top of my head which
chip is used (maybe 2716?). Will have to check my notes at work next
week. It's already an "open" radio but you would have to program in
specific ham freq's that you want to use. Not a good ham radio for
this and other reason's. The licensing rule applying to working on
marine radio's only applies to things that would affect the
transmitted signal. If you only want to use it on the ham bands then
it doesn't matter.

Eric
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Default SEA 112 radio advice / manual / schematic needed

I figured it may not be worth much, maybe parts. I am licensed by the
FCC for commercial work - general radiotelephone with no radar endorsement.

The 112's value to me would be to put it on the amateur band(s), or
failing that, maybe salvage the nice-looking RF PA from it to drive this
old AM ham rig I've been restoring.
http://www.bunkerofdoom.com/tuckerkw...ansmitter.html

Bottom line is I like to build/modify and am not adverse to take on
something unusual.

By your other comments (trim to save BW), I take it there are as many
'FCC problems' around the marine community as there are inland. Not
comforting, but misery loves company.


Thanks,
Patrick



Larry wrote:
patrick jankowiak wrote in news:Q4Nvj.7445$Ru4.5658
@newssvr19.news.prodigy.net:

I've read at least one case of a mariner throwing one
away, so they must not be too valuable..)


That's pretty good advise.....as good as any you'll get here.

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Default SEA 112 radio advice / manual / schematic needed

Thank you Eric,

I see.. Due to the EPROM, channel selection would be quite limited, and
I no longer have a burner or EPROMs. I'd be making a convenient marine
rig into an inconvenient ham rig. If that's how it works, I don't want
to ask you to go to that much trouble.

-Living in Dallas, there are many, many HF frequencies in use by locals,
and it's a reality to have to nudge the dial often. Not sure anyone
around here would want it for their boat.. all we got is lakes!

best regards,
Patrick



wrote:
On Feb 22, 11:14 pm, patrick jankowiak wrote:
1. How are the frequencies programmed in? I see no crystals or diode
matrix for programming the channels as I would expect in an older set.


It uses eprom programming. It's been a while since Iv'e worked on
one of these but I have a service manual and have reprogrammed these
radio's. As I recall, it's kind of weird how it's done, but you'll
need a basic eprom programmer. I can dig out my notes and give you the
details on programming. Don't remember off the top of my head which
chip is used (maybe 2716?). Will have to check my notes at work next
week. It's already an "open" radio but you would have to program in
specific ham freq's that you want to use. Not a good ham radio for
this and other reason's. The licensing rule applying to working on
marine radio's only applies to things that would affect the
transmitted signal. If you only want to use it on the ham bands then
it doesn't matter.

Eric

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First recorded activity by BoatBanter: Feb 2008
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Default SEA 112 radio advice / manual / schematic needed

I did some www searching.. most of them, except the one that was being
threatened to be pitched out, seem to be in boats that are for sale or
for hire. Maybe it's an old reliable workhorse? I didn't mean to imply
that they are being decommissioned wholesale.

There is lots of room to work inside inside for the adventurous, but I
won't go as far as modifying a PLL or DDS circuit on this one. I have
some precision RF generators that could sub for VCXO's, and any
bandswitching control could be outboarded, but then it wouldn't be too
portable.

thank you,
Patrick

msg wrote:
wrote:

On Feb 22, 11:14 pm, patrick jankowiak wrote:

1. How are the frequencies programmed in? I see no crystals or diode
matrix for programming the channels as I would expect in an older set.



It uses eprom programming.


This sounds like a good candidate for conversion using an additional
mcu; does the rig use DDS or PLL synthesis? How many stages of
conversion? If it is a routine discarded item, I must begin a
quest for some of these ;-)

Michael

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Default SEA 112 radio advice / manual / schematic needed

patrick jankowiak wrote in news:eN5wj.3442$tW.3335
@nlpi070.nbdc.sbc.com:

old AM ham rig I've been restoring.
http://www.bunkerofdoom.com/tuckerkw...ansmitter.html


Wow! Looks like my dual 4-1000A common cathode linear from the 70's!
It was built into a 24" WW2 Navy rack 7' tall. Being grid driven, 5
watts into its 50 ohm input dummy load could easily drive it to amazing
power levels, reducing RG-8A to melted plastic. Input was a drained
7200V, 5KVA power pole transformer hooked up backwards with a 30A 230V
Variac to control plate voltage. Home brew choke input filter with
power company oil-filled line power factor compensating caps, 8 mfd at
10KV times 8 caps in the bottom. Hand wound a filament transformer from
another power company core to power the two 4-1000A filaments with soft
start inrush protection.

Screens were properly powered with a variable tube regulated screen
supply to keep it linear that also provided tube-regulated grid bias
supply. Of course, tuning the tetrodes used as much screen current
indication as plate current to get the tubes operating in the most
efficient range. Running 6KV on the plates, they hardly glowed red at
950ma of Ip...That's about a kilowatt ain't it?...(c;

Plates were in parallel, shunt feeding a big rotary inductor, 25KV
vacuum variable plate and 2-section large transmitting air variable load
cap through two RF relays a friend at a shortwave broadcast station gave
me for the project.

You can tell the tuning's about right when your neighbors can't shut off
the flourescent lights in his garage when you're on 75 meters.

I like your Tucker. Any boat anchors that can be saved really need to
be. Not many of us can afford a Harris DX50.

I'm not on the air any more. I keep the license, just in case I get re-
interested or someone takes the internet away from me. Skype DX beats
6KW on 20 meters hands down and noone bitches I'm on their favorite net
frequency on Skype. I even use it mobile over Alltel's Sellphone
broadband.


Bottom line is I like to build/modify and am not adverse to take on
something unusual.

By your other comments (trim to save BW), I take it there are as many
'FCC problems' around the marine community as there are inland. Not
comforting, but misery loves company.


No FCC problems, really, unless someone complains. Most boaters with
SSB don't understand that they can run a LOT more power than 150 watts,
legally, if they'll just go take elements 1 and 3 to get a Radio
Operator's License for over 350 watts. The ship license for the tiniest
sailboat covers it with a proper operator license a the big transmitter.

Most sailors are so afraid of USING HF, outside of a few chat nets just
above 4 Mhz, they'll have no trouble. FCC has too few enforcement
people left after the PURGE and closing of lots of monitoring stations a
few years back to worry about small yachts. They're doing ship
inspections to make sure the ship operators are compliant with the regs.

Good luck on your SEA restoration.....(c;

Larry

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