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Author Topic: coax adapters  (Read 1706 times)
AD7XN
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Posts: 36




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« on: February 14, 2013, 11:59:37 AM »

If I connect an VHF to N Adapter to any of the connectors in an transceiver to antenna system, how does it effect the Constant Impedance characteristics of the N connector ?   For an example;-transceiver VHF adapted to an LPF with N connectors, or antenna switch ?

Would it be better to change the N connectors to VHF ?  Is there any advantage in using N connectors in the entire system, meaning changing out all the VHF connectors to N's, on all of the gear in an strictly HF set up ?

Thanks
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WB6BYU
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Posts: 13121




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« Reply #1 on: February 14, 2013, 12:55:59 PM »

If you're installing new connectors, it might make sense to use type N throughout
the system.  They are supposed to be more waterproof.

At HF, you won't notice any significant difference.  Even at 70cm the actual impedance
mismatch of the PL-259 is relatively small.  Above that you would probably want to
use type N.
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WB2WIK
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« Reply #2 on: February 14, 2013, 02:22:59 PM »

I agree with Dale.

Below 450 MHz or so the real thing to watch out for when making transitions is the quality of the adapters.

I've seen some "imports" (and "Radio Shack" types) that were horrible and quite lossy, evidently made of materials that probably shouldn't have been used for this.

But the U.S.-made Amphenol, Kings, Pomona, Trompeter, et al (people who are qualified to manufacture mil-spec connectors and adapters) are very good and have no measurable insertion loss up through the VHF spectrum.
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K8AXW
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« Reply #3 on: February 14, 2013, 04:57:30 PM »

I went through this very thing several years ago on the advice of a very electronics savvy engineer. 

I learned much later that this was his "opinion" and was based on very little actual fact.  I gradually went back to the PL-259/SO-239 connectors and now I have a load of N connectors and rotary switches taking up drawer space.

For HF, save you money.

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G3RZP
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Posts: 4445




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« Reply #4 on: February 15, 2013, 12:44:45 AM »

You definitely want to watch some of the right angle adpators in PL259/SO239 type. Some of them have a a small spring coil to do the connecting and make a real impedance bump at VHF.  Reputable manufacturers such as Greenpar, Amphenol and  Huber and Suhner are OK.

As far as PL259s are concerned, good Teflon insulated silver plated are the way to go. 12 for $10 at Dayton last year.
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K8AXW
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« Reply #5 on: February 15, 2013, 09:04:41 AM »

Peter:  You have made a very good point here.  I had an antenna problem once that just about had me on the ropes!  Long story short I found the brand new right-angle PL-259s were the problem.

I didn't understand that until I dissected two of them.  One of the new ones and an old one.  Found the new ones had a coils spring between the contacts and the old on had a solid connector.

Can't recall if it was VHF or HF but I've made it a point not to use right-angle connectors anymore!

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G3RZP
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« Reply #6 on: February 16, 2013, 02:47:28 AM »

'AXW,

So I wasn't the only one.......

I still use right angle adaptors, but they are genuine Amphenol dating from WW2!
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