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Author Topic: Mic 8 pin to RJ45 connector  (Read 3364 times)
W4NRY
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Posts: 37




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« on: April 12, 2012, 07:35:59 AM »

I want to adapt a microphone with a Foster 8 pin connector to a modular pin input to my Yaesu FT-900. I'm thinking of using CAT5 cable with a male 8 pin connected to an RJ45 connector.

Is length a critcal factor?
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K8AXW
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« Reply #1 on: April 12, 2012, 08:40:26 AM »

No.  Unless perhaps you're planning to run the mic cable from upstairs to the basement and out to your garage shack.   Grin
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KB1GTX
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« Reply #2 on: April 12, 2012, 03:34:54 PM »

I replace a d104 cable with 6 feet of cat5 for my ft857 and works great.
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KB5ZSM
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Posts: 70




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« Reply #3 on: April 14, 2012, 03:56:33 PM »

Yes, length can be a problem. The wire is not properly shielded and if you have any RF in the shack, you will have a feedback problem. It isn't hard to wire a regular mic. cable to the RJ45. Just twist your shield wire and tin it. Then arrange your wires in order and trim them evenly. Check your fit in to the connector and when satisfied, crimp. Sometimes when I want that little extra strength, I will put a little super glue on the area where the cable enters the connector (but not so much that it runs down to the connections. I just made a replacement cable for my IC-7000 that needs two RJ45s.

Win (KB5ZSM)
Tip Top TV
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K8AXW
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« Reply #4 on: April 14, 2012, 09:05:56 PM »

Win:  I considered that when I made my abrupt answer.  CAT5 cable is foil wrapped and has a "drain" wire.  I assumed (ASS-U-ME) that the ground lead would be connected at each end.  If it is, it should be OK. 

I have CAT5 strung through the house connecting my computers and run high power.  No problem. 

The tongue in cheek comment about the run length becomes reality if indeed he intends to run a long piece.  There is always the IR losses in wire for anything from DC to daylight.
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KB5ZSM
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« Reply #5 on: April 15, 2012, 01:34:17 AM »

To K8AXW -- Don't laugh but I have seen cheap CAT5 that doesn't have shielding, Just 4 pairs of twisted wires. That was the bases of my reply. I hadn't even considered what you had said about long long stretches but your also correct about losses. You can use the shielded type with no problems but I have also had great easy success using regular Microphone cable. I have replaced many missing RJ45s on our county's radios that have the coiled mic. cables.
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W4NRY
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« Reply #6 on: April 17, 2012, 06:57:29 AM »

Thanks to all.
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K8AXW
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« Reply #7 on: April 17, 2012, 07:45:49 AM »

One thing I never considered was the cable flexibility.  This is where cable designed for a specific use should be used.  Microphone cable usually is quite flexible or supple whereas most CAT5 cable is on the stiff side. 

But then one has to consider the cost and availability........   This is what is great about ham radio.... doing with what you have!
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KJ4RWH
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« Reply #8 on: April 18, 2012, 08:18:14 AM »

To K8AXW -- Don't laugh but I have seen cheap CAT5 that doesn't have shielding, Just 4 pairs of twisted wires. 

I believe that's what UTP refers to. (Unshielded Twisted Pair) probably 95% of what you'll find in use. The twisted pair element provides its own shielding by what's known as Common Mode Rejection.
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W9GB
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« Reply #9 on: April 18, 2012, 08:42:15 AM »

EIA/TIA 568a established the infrastructure standards in early 1990s, and is revised/updated on regular basis.
http://en.wikipedia.org/wiki/Twisted_pair
Unshielded Twisted Pair (UTP)stat is Category 5 or 5e will be the most common LAN cabling you find (everywhere).

Screened Twisted Pair (ScTP) is more common in Europe, especially Germany.
Newer Las Vegas casinos adopted ScTP in 1990s to reduce RFI / EMI issues.  
The screen is usually a Foil shield, like BeldFoil (Belden trademark).

Belden 1533
http://rj45s.com/Belden_1533P_and_1533R.html

Shielded Twisted Pair (STP), like the old IBM 2-pair Type 1 cabling of the 1980s --
is used where shielding is required. Cat 7 or Grade F cabling is adopting this approach.

You CAN purchase 8-pin modular connectors that have a metal component for Screened Twisted Pair (ScTP).  These connectors are more expensive, and a bit more difficult for hobbyists to find.
http://www.twacomm.com/catalog/model_IC1078S500.htm

http://www.rj45s.com/M57623_Cat_6_OSP_ScTP.html
« Last Edit: April 18, 2012, 08:57:08 AM by W9GB » Logged
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