Good place to buy RF jumpers (US)?

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radiowave911
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Good place to buy RF jumpers (US)?

Post by radiowave911 » Tue Jan 05, 2016 7:15 pm

While I could get the parts and roll my own, I really would rather buy than build in this case.

Our QEI transmitter has been giving us fits. Finally came down to 2 modules with (among other things) failed voltage regulators.

The parts all came back today. I reinstalled everything, checked all my connections and fired it up. Switching between forward and reflected on the exciter, the needle didn't move. That is what is commonly called a bad thing. Shut down, open the transmitter back up (the exciter has a rack mount spot in the top of the chassis), went to check the connector on the back of the exciter - had the cable in my hand, the connector still on the back of the exciter. The cable and connector were no longer mated. Much cursing ensued.

Found an unused N connector for RG8 (the cable coming from the exciter - yes it is overkill for the exciter output, but it is what we have). Cut the bad end off, installed the new connector. Hooked everything back up, things came up beautifully. Time to button things back up. Note that the power controller was sitting on the floor at this time, not re-installed in the transmitter chassis.

Shut back down, reinstall power controller, fire things back up. Forward and reflected on the exciter match. Again. Much cursing ensued.

Shut back down, pull power controller. Decide to fire up transmitter for goofs & grins (either that, or I am a masochist), making power. No reflected on the exciter. Looking good. Can't find anything wrong otherwise, checked to make sure there wasn't some odd short between the power controller and the transmitter chassis. Looks good to me. Must be the cable.

I need a N Male to N Male 50 Ohm jumper cable about 6 feet long. Needs to handle at least 100W (gives me plenty of breathing room should I have a need to press the transmitter into service again bypassing some internals). Where would YOU go to get such a cable?
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Re: Good place to buy RF jumpers (US)?

Post by ChuckG » Wed Jan 06, 2016 2:17 am

Pasternack will have what you want in stock, but you'll pay for it. Probably $90 for a right-angle N/N with RG8.

I used to maintain a FMQ10000 and had similar troubles with the auto power controller. It controls drive by running the exciter power through an electronic attenuator. When that fails it shorts the exciter to ground, or goes completely open, and it failed a lot. I finally just bypassed it and set power with the exciter output. Are you certain it's the cable?
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Re: Good place to buy RF jumpers (US)?

Post by TPT » Wed Jan 06, 2016 6:58 am

CablesOnDemand.Com

You can get a 5 foot RG213 N to N jumper for $17. I have a number in service--they seem to work OK.
They are in Endicott (Binghamton area) NY.

For specialized cables try Dave Edmiston at RF Specialties/Pennsylvania. More expensive, of course, but I've had them make up a 20 foot superflex for an LPFM installation (needed to run it from the base of the tower, through a trough, to the little Nautel transmitter), as well as a 3' 7/8th DIN to a 7/8th EIA for one of my stations (the transfer switch is mounted in the same rack as the transmitter).

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Re: Good place to buy RF jumpers (US)?

Post by kkiddkkidd » Wed Jan 06, 2016 7:26 am

Tessco will have some standard length cables (1,3,6,8ft etc) but you can probably have them made locally at a 2-way shop. I bought a set of crimpers and common connectors from PowerWerx several years ago and keep some LMR240 and LMR400 around just for building special cables. I seem to make more cables for my ham projects than paying work but it is very handy to have around.
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Re: Good place to buy RF jumpers (US)?

Post by kcbooboo » Wed Jan 06, 2016 8:04 am

Good crimp-on male N connectors cost $4-$5 each. I usually use silver-tinned RG-214. I bought some for $1/ft but lately it's been closer to $3/ft. Takes a few minutes to prep each end. Based on that, $17 is a good price for a 6ft cable.

There are loads of companies that will make cables to your specs. You tell them what each end connector is, what type of cable to use, and how long. These are especially handy for single cables where the ends are different or uncommon or where you'd have to buy $25-worth from some supplier.

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Re: Good place to buy RF jumpers (US)?

Post by NECRAT » Wed Jan 06, 2016 6:53 pm

Ramtronix out of Long Island will as well. Walter there is a good guy to deal with and I've had him make me RF cables in the past that worked excellent. He even got me a very expensive, specialized cable from a company that only did bulk, because he had connections there. 800-528-4550
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Re: Good place to buy RF jumpers (US)?

Post by Deep Thought » Thu Jan 07, 2016 11:05 pm

http://mpddigital.us/

I've been using Kim's company for years and they are fast, inexpensive and produce a quality product. Plus you're supporting a USA woman-owned small business.
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Re: Good place to buy RF jumpers (US)?

Post by rich wood » Sun Jan 10, 2016 8:16 pm

I have had good luck with:
http://www.testedrfcables.com/

Their price, quality and turn around time is very good.

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Re: Good place to buy RF jumpers (US)?

Post by radiowave911 » Tue Jan 26, 2016 8:22 pm

ChuckG wrote:...Are you certain it's the cable?
Reasonably certain. No idea where this one came from in the first place (I do not think it is original). Given that the connector literally fell off one end after having been in service for at least 7 or 8 years, I am guessing the other end may have issues as well. I would rather get a known good cable.

I also saw a comment on the power controller failure modes. This controller just came back from the factory. It was one of the first components we suspected was causing our problems (which ultimately turned out to be 2 failed regulators).

Unfortunately, this has slipped over the last couple of weeks, and I am finally getting back to it (the problems of being a part-time engineer for a public school district - I have a 'real' job to pay the bills - that has been nuts lately). I am checking in with MPD. I like the idea of supporting women-owned, minority-owned, local, etc. companies whenever it makes sense to. I will even pay a bit more if I have to. The quality has to be there, though.

Thanks
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Re: Good place to buy RF jumpers (US)?

Post by rich wood » Wed Jan 27, 2016 10:41 am

Hello Deep Thought,
I tried using the MP Digital web site. Not much for product listing and their contact page does seem to work? How can I reach them? Thanks

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Re: Good place to buy RF jumpers (US)?

Post by Deep Thought » Wed Jan 27, 2016 12:08 pm

She sells mostly through eBay and Amazon. For example: here are the current listings. She will make any length with any connector, though. I usually just contact her through eBay with what I want, she puts up a listing and I buy it.

Her Amazon store is here.
Mark Mueller • Mueller Broadcast Design • La Grange, IL • http://www.muellerbroadcastdesign.com

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radiowave911
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Re: Good place to buy RF jumpers (US)?

Post by radiowave911 » Wed Jan 27, 2016 8:13 pm

rich wood wrote:..their contact page does seem to work...
I notice that as well when I went to the site. The issue is that the SSL certificate for the contact page expired December 31, 2015. I took a look at the cert and allowed my browser to accept it anyway, which allowed the page to display. Firefox on Ubuntu Linux.
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Re: Good place to buy RF jumpers (US)?

Post by jammerdave » Thu Jan 28, 2016 11:03 am

Also, CableXperts has served me well, and is reasonable. I usually bought them through Amateur Electronic Supply or Ham Radio Outlet. Also bought a lot of cables through Tessco and Talley. http://www.cablexperts.com/cfdocs/cat.c ... ship=1&c=0

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Re: Good place to buy RF jumpers (US)?

Post by radiowave911 » Tue Feb 02, 2016 5:43 pm

Following up - I have an order on the way right now from MPD. Very easy to deal with.

Thanks, all for the responses!
Meddle not in the affairs of dragons, for thou art crunchy and taste good with ketchup.

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