Marti STL-10 tx issue

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smalltownbroadcaster
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Marti STL-10 tx issue

Post by smalltownbroadcaster » Fri Jun 03, 2016 9:58 am

Hello,

We run a dual mono STL-10 setup for our STL. One of the marti tx's is going kaput on us; and it's time for us to explorer another alternative. This is like the 3rd refurbished unit we've installed; and we just cannot get over the curse of these things going out.

Obviously, once again replacing the one marti tx would be the simplest; as the other 3 pieces are still functioning okay.

Aside from ubiquity, which wont work for us (too much interference)...anyone have any good, affordable alternatives? Anyone have an STL-10 transmitter laying around? 2,000$ for a refurbished unit from Bohn is not attractive, as this would be our 4th refurbished unit from them. And they just keep breaking.

Should we explorer a different brand? Thoughts?

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Shane
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Re: Marti STL-10 tx issue

Post by Shane » Fri Jun 03, 2016 10:05 am

Look in the For Sale section. A set was just listed earlier this week.
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Deep Thought
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Re: Marti STL-10 tx issue

Post by Deep Thought » Fri Jun 03, 2016 10:42 am

Since you already have antennas that might work at 900 MHz you could take a look at the Ubiquiti unlicensed 900 stuff.
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kkiddkkidd
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Re: Marti STL-10 tx issue

Post by kkiddkkidd » Fri Jun 03, 2016 11:32 am

I have several clients running Nicom STL RX/TX/Pairs and they seem to work OK for the money. The newer units are better than the old 2ru units.

AND they support both mono and composite. There are several of the offshore brands that are all OK if budget is an issue.

I have noticed that sometimes when replacing a Marti TX with a Nicom that the audio levels have to be dramatically reset on both ends. I suspect that someone had kludged the TX and RX metering to make up for very low TX mod. They were both supposedly the same emission designator.
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smalltownbroadcaster
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Re: Marti STL-10 tx issue

Post by smalltownbroadcaster » Fri Jun 03, 2016 1:16 pm

Deep Thought wrote:Since you already have antennas that might work at 900 MHz you could take a look at the Ubiquiti unlicensed 900 stuff.
Hi Deep Thought,

Thank you. We do have Para Mini-Flectors at both ends of the link for the Marti's....

How do you interface a Ubiquiti radio to these antennas?

smalltownbroadcaster
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Re: Marti STL-10 tx issue

Post by smalltownbroadcaster » Fri Jun 03, 2016 1:31 pm

kkiddkkidd wrote:I have several clients running Nicom STL RX/TX/Pairs and they seem to work OK for the money. The newer units are better than the old 2ru units.

AND they support both mono and composite. There are several of the offshore brands that are all OK if budget is an issue.

I have noticed that sometimes when replacing a Marti TX with a Nicom that the audio levels have to be dramatically reset on both ends. I suspect that someone had kludged the TX and RX metering to make up for very low TX mod. They were both supposedly the same emission designator.
Thank you Kkidd.

Question though; since these marti's are obviously licensed....could we run and 'off shore' brand the TX side of one of the frequencies? Would we have to amend our license filing to do this? Is it okay to just replace 1 transmitter in the group of 2 transmitters and 2 receivers, assuming the frequency was obviously set correct.

I do like Deep Thoughts idea of interfacing a Ubiquity 900 with the Mini flectors; just not sure how that would work.

smalltownbroadcaster
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Re: Marti STL-10 tx issue

Post by smalltownbroadcaster » Fri Jun 03, 2016 3:30 pm

Just as simple as SMA to N adapter to connect the ubiquity to Miniflector??

Anyway to run both a marti frequency and the ubiquity on the same antenna?

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Re: Marti STL-10 tx issue

Post by kcbooboo » Sun Jun 05, 2016 5:36 am

Just out of curiosity, what's not working on the bad TX? Audio? RF? Bad or no meter reading in some positions? I only ask because I repaired two pairs last year and they didn't seem to be that hard to work on.

Bob M.

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Re: Marti STL-10 tx issue

Post by TPT » Sun Jun 05, 2016 5:56 am

The supply can be a weak link on the STL transmitters. I believe a 4 amp 15 volt switching supply would work as a replacement.

Some series used the surface mount capacitors--these were problematic. And, of course, given the age of the design, plain old leaky caps can be the problem. If you open it up and see the bright blue Phillips axial caps--get out the soldering iron.

Switches: The front panel switch can get dirty and need to be exercised, of course, doesn't affect operation of the unit. On the audio board there are two switches (in both transmitter and receiver) that set pre-emphasis and de-emphasis. They can get dirty, intermittant, but usually can be cured by exercise.

Environment can be a problem. In crowded racks with little ventilation, anything can overheat. I have a Middle Atlantic fan panel rear mounted in my transmitter rack blowing cool air across the heat sinks of my pair of 606 composite transmitters ( the building has a 10 kw FM transmitter for one station, while the Moseleys feed another station and booster of that same tower).

Generally, my experience is these things run till they die.

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kkiddkkidd
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Re: Marti STL-10 tx issue

Post by kkiddkkidd » Sun Jun 05, 2016 8:19 am

smalltownbroadcaster wrote: Thank you Kkidd.

Question though; since these marti's are obviously licensed....could we run and 'off shore' brand the TX side of one of the frequencies? Would we have to amend our license filing to do this? Is it okay to just replace 1 transmitter in the group of 2 transmitters and 2 receivers, assuming the frequency was obviously set correct.

I do like Deep Thoughts idea of interfacing a Ubiquity 900 with the Mini flectors; just not sure how that would work.
I believe that you would have to do a mod but someone else can probably answer definitively. I am going to guess that if your license is over a few years old, it is incorrect anyway. I have checked dozens of STL/RPU licenses around here and found about 25% of them to be complete and correct. We have straightened out a number of them but the incomplete/incorrect ratio is still probably over 50%.

To diplex/duplex a 900 UBNT radio with an operating 950 STL you will need a diplexer/duplexor. I have never done it so am not sure exactly what hardware is available but I have heard several people using Moseley LanLink duplexers. I recall seeing someone mention $1k for the Moseley duplexer new.

If you are going to use the UBNT by itself on an existing 950 antenna, the appropriate connectors and cables are all you need.

Be aware that there are only about 5 high bandwidth non-overlapping 900 channels and most of those channels are probably in use by your friendly local WISP operators. At least that is the case here in rural middle-TN.

If your path is clear and not too long, you can cheaply do a 5.8 link that might be more robust.

Good luck,
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Kevin C. Kidd CSRE/AMD
WD4RAT
AM Ground Systems Company
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KK Broadcast Engineering
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kcbooboo
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Re: Marti STL-10 tx issue

Post by kcbooboo » Sun Jun 05, 2016 10:14 am

A duplexer is used to allow a transmitter and receiver to operate at the same time through one antenna. Tuned band-pass and band-reject filters keep the signals going where they're supposed to (TX to ANT, ANT to RX).

A diplexer is used to allow two pieces of equipment to share one antenna. Tuned band-pass and band-reject filters isolate the various signals (port1 to ANT, port2 to ANT).

The LanLink 902-928 MHz product uses a diplexer in the associated 950-960 MHz STL TX or RX chassis to share the single antenna between the STL radio and LanLink radio.

The LanLink itself is a half-duplex unit. It either transmits or receives in any given instant. It does NOT do both at the same time. It can get away with this because most network traffic occurs that way. The unit receives a data packet from the network, makes sure there's no incoming RF signal, turns on its TX, sends that data packet, turns off its TX, then waits for some acknowledgement from the other end.

I don't know if the Ubiquiti equipment works the same way. Obviously an analog STL is uni-directional, as the name suggests.

Bob M.

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Deep Thought
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Re: Marti STL-10 tx issue

Post by Deep Thought » Sun Jun 05, 2016 9:23 pm

kcbooboo wrote:The LanLink itself is a half-duplex unit. It either transmits or receives in any given instant. It does NOT do both at the same time. It can get away with this because most network traffic occurs that way. The unit receives a data packet from the network, makes sure there's no incoming RF signal, turns on its TX, sends that data packet, turns off its TX, then waits for some acknowledgement from the other end.

I don't know if the Ubiquiti equipment works the same way. Obviously an analog STL is uni-directional, as the name suggests.
Most WiFi is half duplex. In the digital world that's not an issue.
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jammerdave
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Re: Marti STL-10 tx issue

Post by jammerdave » Mon Jun 06, 2016 9:50 am

I believe this to be the only diplexer option, same as in the Moseley LanLInk gear. We're going to be implementing some as well.

http://www.microwavefilter.com/18486.htm

df

smalltownbroadcaster
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Re: Marti STL-10 tx issue

Post by smalltownbroadcaster » Mon Jun 06, 2016 11:13 am

jammerdave wrote:I believe this to be the only diplexer option, same as in the Moseley LanLInk gear. We're going to be implementing some as well.

http://www.microwavefilter.com/18486.htm

df
Was looking at this too. About 800$ each. Question; is this needed at both ends.... since obviously your transmitting from Mountain to Studio as well with the lan side of things.

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kkiddkkidd
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Re: Marti STL-10 tx issue

Post by kkiddkkidd » Mon Jun 06, 2016 6:39 pm

Yes... Unless you can run a dedicated antenna at one end or the other.
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