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Off Air Audio
Topic: Obsolete 300 ohm connectors for the REL.

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Posted by oatman on 01-26-2009
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Hello All;

Any idea where I can get an antenna connection for an REL tuner. It appears to be a clear plastic connector with holes in one end and set screws to secure the strands of a 300 ohm dipole antenna with another end that plugs into the back of the tuner. I understand that this may have been a common connection set up back in the 50's but I just get blank stares when I ask in RadioShack or local electronic supply houses.

Thanks for any ideas

Posted by Joe Roberts on 01-27-2009
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Yes, that WAS a common connector but this won't help you now. Radio Shack sold those as recently as ten years ago.

Since the female side of the connectors has spring terminals there is some variability permitted in the diameter of the male contacts. I suggest trying speaker cable pins and test probe pins. Speaker pins tend to be a little thinner than the pins on that connector, but might work. In a pinch, a few pieces of 16 ga. or so solid core wire might work.

Most antennas today would not be 300 ohm balanced twinlead. If you consult the manual, I believe that you will find that 75 ohm unbal only connects to one side of that connector and ground.

Check the connector from the back and see if it is possible to thread wires through the connector holes, in which case you can have a ground coming through one hole and a hot coming through the other. Terminate these wires in a 75 ohm F or BNC per your requirements. Of course with the coax connector installed, you will no longer be able to remove the cover but how often will you need to do that?

The other alternative is to get a 75ohm to 300 Balun and solder solid core wires or pins to the side with the spade lugs in order to plug into the connector. This is what I did when I used my last twinlead connector. There will be some loss with your average cheap balun but the REL has excessive sensitivity for urban situations anyway, so you should be fine.

One other suggestion: look on ebay for old rabbit ear TV antennas that might have that connector. Although most had spade lugs, I have seen some with the moleded lucite twinlead plug that you need. As you suspected that is a 1950s item. By the sixties, most FM/TV twinlead terminations were screw terminal.

Posted by drdna on 01-27-2009
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Like this one?

http://cgi.ebay.com/AweSoMe-Vintatge-50s-TV-Antenna_W0QQitemZ250363939125QQihZ015QQcategoryZ73374QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

Adrian

Posted by Joe Roberts on 01-27-2009
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You cant see the end of the wire to know if it has a connector.

This might have been a stupid suggestion because most of those antennas will have spade lugs or no connector whatsoever, just bare wires.


Posted by Romy the Cat on 01-27-2009
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Oatman,

I might understand that you have a desire to keep your REL as authentic as possible (that I feel is not a dignified objective to begin with – this is Tuner not the Fabergé Egg), but if you go not for a look but for the actual result then trash all that crap that REL put in there and run a plane and simple BNC connector right to the front end. Perhaps it is me but in all tuners that I have I get rid any connectors and replace them with BNC. The BNC connectors are in use for many decades in measurement equipment and Good know why anything else was “invented”. In my view BNC is so perfect that any further “progress” had to be abandon.

The Cat

Posted by Joe Roberts on 01-27-2009
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Keep in mind that there are 50 ohm and 75 ohm BNC connectors. The inner pins are different sizes. If you plug a 50 ohm male into a 75 ohm female, you will stretch out the receptacle and, over time, ruin it.

There are also impedance matching considerations but the practical  effect on receiving apps is nil.

A 75 ohm male usually makes contact with a 50 ohm female, but it is a close call. For 75 ohm FM apps, it is best to search out a 75 ohm female BNC.

BNC is far from the ultimate VHF connector, but it is far more than adequate for casual indoor receiving applications--certainly better than anything that bolts to 300 ohm twin lead.

Posted by Joe Roberts on 09-26-2009
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Just scored a box of these obsolete 300 ohm connectors for the REL.

Drop me a line if you need one. Free to any REL owner.

Joe

Posted by mark2870 on 04-13-2010
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Joe,

How can I get one? Or, even a picture would help.

Thanks.

Mark

Posted by Joe Roberts on 04-13-2010
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Gimme a couple days to find the box and I'll send you a couple.

PM or email your address.

Joe



Posted by oatman on 04-13-2010
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Hi Joe;

Just received notification of recent responsis re: my origonal question over a year ago. Let me know if you locate the box and can send a couple as I really need them. (Getting around to finally setting up 2 I have in a new system)

Thanks so much and best regards!

Dave

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