[MRCA] SEA 112 HF Marine Transceiver

[Christopher Bowne]

I intend to power it up at least on receive, at this point, but without a manual to understand how it operates on transmit, I’m hesitant to operate it in that mode.  It has a big socket on the rear panel for interface with a remote antenna tuning unit, it’s not clear what the direct output from the radio expects to see as a load.  It’s also not clear what the actual channel frequencies are set up for as there is no direct frequency readout indication, just channel and band switch positions.  I suppose that I can sweep the receiver with my URM-25 signal generator, using my HP freq counter to give a high resolution of the sig gen output to get at least some idea how it is set up.  

I believe it came off of one of the commercial fishermen’s boats that operate out of Stonington.  Very little info available on anything SEA on-line.  They merged with Datamarine International of Pocasset MA way back in 1986.  

I may start pinging the local marine electronics service folks in the area, chances are they might be of help and have documentation on file.  I know at one time one of them was also active on the local jam repeaters.

Chris AJ1G Stonington CT

Sent from my iPhone

> On Jun 27, 2023, at 08:49, mstangelo at comcast.net wrote:
> 
> Chris,
> 
> I have a SEA 322 but could not find any information on the SEA 112. My 322 can be configured via a keypad to operate on the Amateur frequencies but I don't see any way to program on the picture you referenced.
> 
> Do you have a dummy load? If so you can check to see if the radio works on the Marine SSB frequencies.
> 
> Mike N2MS
> 
> 
>> On 06/25/2023 10:08 PM EDT Christopher Bowne <aj1g at sbcglobal.net> wrote:
>> 
>> 
>> Found a reportedly working condition one of these radios at a local secondhand marine supply store today. Followed me home for very little money. Does anyone have any experience using this set on amateur frequencies? Channelized set, capable of SSB and AM, I’m guessing it’s capable of about 100 watts output. Have not found much information on it online so far. Someone else posted a thread on a marine electronics forum on how to use them on amateur frequencies but very little
>> Info there. Someone mentioned that the operating frequencies were set using programmed settings on an EPROM….
>> 
>> Here’s a stock image of one of them.
>> 
>> https://www.hfradio.com.au/codan_%20barrett_qmac%20hf_radio_information/RADIOS/sea_112.htm.
>> 
>> Thinking perhaps a DDS might be used to develop the required excitation to the mixing scheme instead of an internal PLL synthesizer?
>> 
>> Chris B. AJ1G Stonington CT
>>