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MRC (Mars Radio Co.) Model M-358

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MRC (Mars Radio Co.) Model M-358

Post by IfYouSaySo » Thursday, 26 October 2017, 22:15 PM

Anyone familiar, seen, or heard of a MRC M-358 Portable CB from the 1970's? There was an SSB model M-458 but that's even more rare than mine. Very cool radio in my opinion. Comes with a shoulder strap case and has a very long center loaded telescopic antenna. Holds 13x C Batteries. The radio itself can be unmounted from the battery box if you want to go mobile with it, the antenna and coax plug is built into the battery box. It has 23 channels. The circuit board has Plugin crystals (Any ideas about swapping out for other frequencies/channels??) I am wanting to get more juice out of this radio. I am new to the forum so I cannot upload any pics or the Schematic yet, so thought I would post some info for a start. Cool thing about some of the older electronic equipment is that you got a wiring schematic with it :-D. This radio came with two options, all "NEC's", a 2SC1957 driver & 2SC1306 final 4 watt output, or a 2SC2028 driver & 2SC2029 final 6 watt output. Mine is the 4 watt. It looks like the driver 1957 is coupled or driven by a 2SC1675L by means of an adjustable coil, not sure if that's the collector or base its going to, need to look at my transistor chart again. There is a 4.7 Ohm resistor going to the 1306 final-(not sure if that's 4.7 or 4.7K, will have to measure it) I am pretty knowledgeable in electronics but by no means an expert, especially with a CB, my experience is more with old tube AM and Shortwave receiving radios. I did do some 2-way radio repair and minor tower repair changing out bad repeaters down in Florida years ago but that was a long time ago and honestly don't remember much about it. So when it comes to alignment, modulation, and all that stuff i would need help. Understand SWR though. All I've ever tried is seeing how a radio sounds with a receiving radio. As far as equipment goes that I own is a snap-on/fluke multimeter, a Simpson 260 5P multimeter (way old school), two L/C capacitance & Inductance meters, an old touch tone TF26 Cricket Transistor checker, and a couple of tube checkers. No scopes or anything like that. What I am wanting to do is get 15-25+ watts out of this radio if possible. well I know anything is possible but I don't want to get into some kind of deep sophisticated procedure where I'm practically changing out every component on the board :shock:. If that's the case then its just not worth the trouble to me. Not on a portable anyways. Here is what I have on hand, a couple of each: Eleflow 2SC1969 for a final (Specs: base voltage should not exceed 0.7 volts/Idling current 45-55mA max) , and 2SC1957 or 2SC2314 for a driver. Don't know if that's the way to go or which combo to use, or if I need to try something totally different? Any suggestions anyone? Hopefully soon I can upload the schematic and a pic that should help more I hope :roll: .....

Thanks, Chris


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Re: MRC (Mars Radio Co.) Model M-358

Post by MDYoungblood » Sunday, 29 October 2017, 8:05 AM

I couldn't find that radio on the internet but did find the M-458, cool looking radio for sure. I have been into radios for over 50 years and had never seen one so the one you have must have came out of Canada or Europe since they weren't sold in the states.

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Re: MRC (Mars Radio Co.) Model M-358

Post by IfYouSaySo » Sunday, 29 October 2017, 17:56 PM

Wow, that's alot of experience under the belt there. You know I never thought about that, it was originally my fathers. The radio is made in Japan and went there several times while in the Navy, he was in the VP-65 squadron during the height of the Cold War, he hunted for Russian submarines on radar. He was also the on board radio repair man if something went wrong in flight. Every flight was over 20 hours, they flew practically from North to South pole over the Pacific and refueled in different places including Japan and Alaska. He brought home several things from Japan. So you must be correct. No wonder I can't find anything on that radio. I did find a picture of one in some kind of radio museum website a few years ago, and now that I'm thinking about it I believe it is an EU site. I will see if I can find it and post the link if possible, don't know if I have permission for that yet. When able I'll upload the schematic as well and see what you think, may just wind up being an experimental project. Or just say forget it, but would be nice to get more than 4 watts out it. Thanks for taking the time on some research! I'll post the rest when permitted

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Re: MRC (Mars Radio Co.) Model M-358

Post by IfYouSaySo » Sunday, 29 October 2017, 19:23 PM

Tried to send a link but still green I reckon. Will retry in time

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Re: MRC (Mars Radio Co.) Model M-358

Post by sonoma » Sunday, 29 October 2017, 21:17 PM

wow MDY I have been into radios myself for a long time. since 1972 I bought my 1st radio and in 1973 started selling them out of my station I owned, started working on them in about 1974 or so. when gas started going so high I had shut down my station in the end of 1976 and just worked on them out of my home some. very few of us oldtimers still messing with the radios.


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Re: MRC (Mars Radio Co.) Model M-358

Post by IfYouSaySo » Wednesday, 01 November 2017, 8:38 AM

[img][/img] [img][/img] [img][/img] Don't know if I'm doing this right or not? I'm use to a paper clip icon for attaching files. Testing....

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Re: MRC (Mars Radio Co.) Model M-358

Post by MDYoungblood » Wednesday, 01 November 2017, 11:31 AM

IfYouSaySo wrote:
Wednesday, 01 November 2017, 8:38 AM
Don't know if I'm doing this right or not? I'm use to a paper clip icon for attaching files. Testing....

First problem is you don't have the post count to post pics but when you do use the "Img-Upload" on the index bar, makes it a lot easier than a third party image poster.

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Maxon HCB-40WX
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Re: MRC (Mars Radio Co.) Model M-358

Post by IfYouSaySo » Wednesday, 01 November 2017, 13:34 PM

10-4. Thanks for the info when able, I thought that might still be the problem but wasn't sure

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Re: MRC (Mars Radio Co.) Model M-358

Post by MDYoungblood » Wednesday, 01 November 2017, 17:07 PM

IfYouSaySo wrote:
Wednesday, 01 November 2017, 13:34 PM
10-4. Thanks for the info when able, I thought that might still be the problem but wasn't sure

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Don't worry, it won't be long now, you will see one of the next couple of posts go right into the topic then you can post pics, change your avatar, and be able to PM/email other members, more privileges come into play as the post count increases. I like https://postimg.org to post on the forum, it is more secure than others and free, two of the reasons the forum uses it. Some others like photobucket but that one is too easily hacked and see everything in your account.

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"321, the Middle of Maryland"

23 AM "WORLD Image WIDE" 38 LSB

Strong Supporter of America's Original Homeland Security Act
The Second Amendment


Base
Uniden Washington
Mobile
Texas Ranger TR-696FD1C
Handheld
Maxon HCB-40WX
Antennas
Avanti Sigma II
Homemade Full Wave Loop
Homemade 1/2 wave Dipole
Hustler 102" SS Whip and Hustler Ball Mount

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Re: MRC (Mars Radio Co.) Model M-358

Post by IfYouSaySo » Wednesday, 01 November 2017, 20:25 PM

Man I sure appreciate the warning and the link! You been very helpful, and patient with us new comers I might add. Guess I need to catch up on the times, will do some more posting soon

Chris

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Re: MRC (Mars Radio Co.) Model M-358

Post by IfYouSaySo » Monday, 06 November 2017, 0:18 AM

Here she is! As MDY mentioned in all his years of being in the CB business he has never seen one, nor have I ANYWHERE except on a CB museum website out of Spain which has now been removed or closed down. Some pictures of the museum can still be seen from another website here https://www.radiomuseum.org/museum/e/mu ... que-cadiz/ CB's and Mics wall to wall. I copy/pasted the picture of mine to the PC about 10 years ago when the site was still up, other than that I have found 0 information on it. So for all I know mine may be the only one here in the States? Hopefully any of you radio mod experts out there can give some pointers on increasing power and modulation output. This radio is free of chips etc so should make things a bit easier. These radios were manufactured in Japan, don't know if they are the original owners of the company but I assume they were, the quality is excellent, a very unique and well made Portable CB. Any extra info on the history of these radios would be very nice if anybody out there in the CB world knows anything about them. If not at least the CBRT Crew will know what one these old rare jewels look like. I will send a pic of the SSB model 458 also. As I mentioned before these radios were designed to be used with a battery pack antenna combo that came with them or could be detached and used mobile. It appears I cant upload the schematic in pdf so I hope the jpeg's will be clear and good enough, if not someone please advise me of a better way to do it.

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Re: MRC (Mars Radio Co.) Model M-358

Post by IfYouSaySo » Monday, 13 November 2017, 17:14 PM

:whistle:

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Re: MRC (Mars Radio Co.) Model M-358

Post by MDYoungblood » Tuesday, 14 November 2017, 7:09 AM

Cool pics and no problems reading the schematics. I think you could do the PDF using the attachment tab. Like you said other than the 458 model I can't find anything on them either.

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The Second Amendment


Base
Uniden Washington
Mobile
Texas Ranger TR-696FD1C
Handheld
Maxon HCB-40WX
Antennas
Avanti Sigma II
Homemade Full Wave Loop
Homemade 1/2 wave Dipole
Hustler 102" SS Whip and Hustler Ball Mount

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