New STL System?

Gotta watch those Fresnel zones!
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lewiscallaway
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New STL System?

Post by lewiscallaway » Tue Jan 12, 2016 7:06 am

The station I do engineering for currently has a Marti STL transmitter and receiver. Would it be worth it to upgrade to a nicer digital system? I was told the internet at the TXer is unreliable, so there goes using a Barix box.

Thanks!

TPT
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Re: New STL System?

Post by TPT » Tue Jan 12, 2016 8:02 am

What kind of system? Composite or discrete?

If you currently have no problems with the Marti system, what's the point?

You own the current path. If the Marti fails, you can easily replace it, and you are back in business. You are protected against on-channel interference--you'll get notices if anyone seeks to operate anywhere near your channel. If you receive interference because of spurs from someone's malfunctioning equipment, they are responsible to clean up the signal.

Now, the expensive on-channel digital systems are much more finicky--any kind of adjacent signal that wouldn't bother the Marti may cause continual problems with a digital system. A more prudent investment would be a used frequency agile STL transmitter, available as a back-up in case the Marti fails--you can find these from time to time for around $1K. Look for Moselley 606C or 6010 series, Armstrong or even another Marti, avoid TFT.

You can go to an unlicensed system (5 ghz), these are not all that expensive but only handle discrete (left and right) channels. And they are unlicensed, so there's no protection against interference. Might make a good back-up but I wouldn't rely on them for a full time STL.

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Slab Bulkhead
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Re: New STL System?

Post by Slab Bulkhead » Tue Jan 12, 2016 10:26 am

Definitely keep your Martis. If your path is clean you should have decent audio. Spare composite STL's are on the used market all the time, so just grab a frequency agile pair for a backup plan in case of failure.

I take care of engineering for an LPFM that has one of the fancy digital systems. It works well but the path is only 2.5 miles so the received signal is quite strong and probably swamps any potential interference. We have an analog backup on the shelf in case the digital goes down. The digitals are expen$ive...let's just say I got really lucky on a grant application.

In my mind, a microwave STL definitely beats dealing with IP or telco circuits any day.

ChuckG
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Re: New STL System?

Post by ChuckG » Tue Jan 12, 2016 10:10 pm

lewiscallaway wrote: Would it be worth it to upgrade to a nicer digital system?
Probably not if you are getting clean, reliable audio out of your current system. I'm not sure what you'd gain.
Depending on which Marti you have, might be worthwhile to replace the power supplies. There are Switchers that are almost a drop in replacement and it really keeps the heat down.
FYI: Bohn Broadcast picked up Marti repairs since Rick Neace's passing. They do good work should you need it.
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Chuck Gennaro
Central Wisconsin

TPT
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Re: New STL System?

Post by TPT » Thu Jan 14, 2016 7:18 am

Believe Rick was using 4 amp/15 volt switching supplies as replacements in the STL-10 transmitters. Variety of such supplies available from Jameco at reasonable prices

TPT
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Re: New STL System?

Post by TPT » Thu Jan 14, 2016 7:34 am

Brain awakening early this winter morning. The composite Marti STL transmitters and receivers use a Meanwell power supply. Just had to replace one in a composite receiver. Turns out that Meanwell had replaced this series supply used in this older receiver (about 6~7 years old) with a newer version --similar part number but the new model supply was just a bit longer than the older model. Questionable whether it would have fit into the receiver.
Luckily Allied Electric still had some of the old model supplies in stock.

ChuckG
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Re: New STL System?

Post by ChuckG » Fri Jan 15, 2016 1:09 am

TPT wrote: The composite Marti STL transmitters .
Last I worked on one of those, the output device was a blue Motorola slab that couldn't be sourced anywhere. Is that still the case?
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Chuck Gennaro
Central Wisconsin

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kkiddkkidd
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Re: New STL System?

Post by kkiddkkidd » Fri Jan 15, 2016 6:58 am

ChuckG wrote: Last I worked on one of those, the output device was a blue Motorola slab that couldn't be sourced anywhere. Is that still the case?
One of the repair depots, (Jsquare maybe?), can retrofit a lower power slab in some Marti tx's. I have not had particularly good luck with the few that I have had converted but it can be done. The best I can recall, it costed about $600/ea to retrofit but it seemed like something else always happened within a year or two of having it done.

Later,
--
Kevin C. Kidd CSRE/AMD
WD4RAT
AM Ground Systems Company
http://www.amgroundsystems.com
KK Broadcast Engineering
http://www.kkbc.com

jammerdave
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Re: New STL System?

Post by jammerdave » Fri Jan 15, 2016 10:35 am

The slab in Marti (forget part number MHW-XXX) was the same used in the older MDS 900 mhz SS serial data transceivers (forget model #) Years ago, I stumbled across well over 250 of those units that came up surplus from a power company on the west coast. I parted out a few to folks that wanted the RF hybrid module, but couldn't hardly give the rest away at the time. Nearly all of them ended being E-cycled, unfortunately. Just thought I'd mention this as a potential source of parts. J-Squared didn't even want the ones I had, as they had plenty at the time, apparently.

dave

ChuckG
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Re: New STL System?

Post by ChuckG » Sat Jan 16, 2016 11:16 pm

jammerdave wrote: couldn't hardly give the rest away at the time.
Now you bring it up. :lol: :D :lol:
Last edited by ChuckG on Sat Jan 16, 2016 11:17 pm, edited 1 time in total.
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Chuck Gennaro
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ChuckG
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Re: New STL System?

Post by ChuckG » Sat Jan 16, 2016 11:17 pm

Ye olde double post. Cellular internet bad. Delete button would be good. :lol:
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Chuck Gennaro
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countrykev
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Re: New STL System?

Post by countrykev » Mon Feb 01, 2016 6:34 pm

These days I wouldn't consider another 950MHz install. If your current system is working, that's fine.

If you are installing a new one, go with licensed 6GHz or 11GHz if you have a short hop. Unlicensed is fine too if you are on a budget and can check the path prior to install.

For that matter, you can get a couple of 900MHz Ubiquiti radios and use your current 950 hardware. Depending on your path you could get 10-20MB of throughput. More than enough for a codec and some web surfing at the site.

There is just too many advantages to having a data path at a site in 2016.
What the heck am I supposed to write here?

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