Repeater Status - 30 July 2014 - Offline

[Luke Jenkins]

While up working on the networking in the shack today, I tested the repeater and couldn't key it up even while at the shack. I power cycled the controller, and got the same result. I didn't have time to dig into what the issue was, so I disconnected the power to the controller.

I'm headed out of town for a spell, if anyone with keys gets motivated to go work on the repeater, feel free. Otherwise I'll be getting the gang together mid August to go check things out.

-Luke

KD7FDH

[John Sohl]

Thank you for all your work and efforts Luke! 

- - - -

John E. Sohl, Ph.D.
Professor of Physics
Weber State University

1415 Edvalson St., Dept 2508

Ogden, UT 84408-2508

voice: (801) 626-7907, fax: (801) 626-7445

cell: (801) 476-0589

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[Jeffrey Page]

Too bad.  It worked about a week ago.  I'll try to at least take a look in the near future.

Jeff

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[Luke Jenkins]

So I think I figured out what the issue was. I had my new FT1D handheld in digital only mode and not auto like I thought. The repeater is probably fine, the controller power just needs to be reconnected. I'm flying out in a few hours and won't have time to reconnect it, sorry about that and the false alarm.

-Luke

On Wednesday, July 30, 2014 5:38:10 PM UTC-6, Jeffrey Page wrote:

Too bad.  It worked about a week ago.  I'll try to at least take a look in the near future.

Jeff

On Wed, Jul 30, 2014 at 5:35 PM, John Sohl <j...@weber.edu> wrote:

Thank you for all your work and efforts Luke! 

- - - -

John E. Sohl, Ph.D.
Professor of Physics
Weber State University

1415 Edvalson St., Dept 2508

Ogden, UT 84408-2508

voice: (801) 626-7907, fax: (801) 626-7445

cell: (801) 476-0589

On Wed, Jul 30, 2014 at 5:29 PM, Luke Jenkins <l...@gmail.com> wrote:

While up working on the networking in the shack today, I tested the repeater and couldn't key it up even while at the shack. I power cycled the controller, and got the same result. I didn't have time to dig into what the issue was, so I disconnected the power to the controller.

I'm headed out of town for a spell, if anyone with keys gets motivated to go work on the repeater, feel free. Otherwise I'll be getting the gang together mid August to go check things out.

-Luke

KD7FDH

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[Jonathan Karras]

This afternoon I plugged back in the repeater controller. I was able to break the repeater at least once. Is the tone 123?

Jonathan

On Friday, August 1, 2014 10:09:35 AM UTC-6, Luke Jenkins wrote:

So I think I figured out what the issue was. I had my new FT1D handheld in digital only mode and not auto like I thought. The repeater is probably fine, the controller power just needs to be reconnected. I'm flying out in a few hours and won't have time to reconnect it, sorry about that and the false alarm.

-Luke


On Wednesday, July 30, 2014 5:38:10 PM UTC-6, Jeffrey Page wrote:

Too bad.  It worked about a week ago.  I'll try to at least take a look in the near future.

Jeff

On Wed, Jul 30, 2014 at 5:35 PM, John Sohl <j...@weber.edu> wrote:

Thank you for all your work and efforts Luke! 

- - - -

John E. Sohl, Ph.D.
Professor of Physics
Weber State University

1415 Edvalson St., Dept 2508

Ogden, UT 84408-2508

voice: (801) 626-7907, fax: (801) 626-7445

cell: (801) 476-0589

On Wed, Jul 30, 2014 at 5:29 PM, Luke Jenkins <l...@gmail.com> wrote:

While up working on the networking in the shack today, I tested the repeater and couldn't key it up even while at the shack. I power cycled the controller, and got the same result. I didn't have time to dig into what the issue was, so I disconnected the power to the controller.

I'm headed out of town for a spell, if anyone with keys gets motivated to go work on the repeater, feel free. Otherwise I'll be getting the gang together mid August to go check things out.

-Luke

KD7FDH

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[Jeffrey Page]

Yes, 123Hz.

Jeffrey D Page

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[Aaron Toponce]

On Fri, Aug 01, 2014 at 08:07:58PM -0600, Jeffrey Page wrote:
> Yes, 123Hz.

I just got a new mobile rig delivered today. I'll be installing it tonight at
home. If someone is on frequency, I would be grateful if they could give me a
signal report.

Thanks,

--
. o . o . o . . o o . . . o .
. . o . o o o . o . o o . . o
o o o . o . . o o o o . o o o

[Luke Jenkins]

If you get home I leave campus (usually about 6pm), I'll be monitoring. I've got terrain in between my home and the repeater otherwise.

-Luke

[Aaron Toponce]

On August 14, 2014 5:09:15 PM MDT, Luke Jenkins <luke...@gmail.com> wrote:
>If you get home I leave campus (usually about 6pm), I'll be monitoring.
>
>I've got terrain in between my home and the repeater otherwise.

I'm transmitting at 50W, and I'm not triggering it. 145.250 with CTCSS 123.0 Hz, negative offset, yes?
--
Not sent from an iThing.

[Jeffrey Page]

Aaron,

Monitoring now, I can get the repeater to respond with the mentioned parameters, so it is working.  I will monitor both the repeater freq. and the offset freq. until I go to bed.

Jeff

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[Aaron Toponce]

On Thu, Aug 14, 2014 at 10:25:32PM -0600, Jeffrey Page wrote:
> Monitoring now, I can get the repeater to respond with the mentioned
> parameters, so it is working. I will monitor both the repeater freq. and
> the offset freq. until I go to bed.

Curious. I have direct line of sight from my house in Syracuse to WSU, near as
I can tell. I'll give it a try again tonight.

[Luke Jenkins]

The frequency we have for the repeater is very noisy as it is used by cable tv; this limits the effective range of the repeater since the noise floor is so high anywhere that has cable tv infrastructure (including campus).

I know that KE7VVT did some range testing when he first set up the current iteration of the repeater so hopefully he can chime in with what kind of range he was able to confirm.

-Luke

[Aaron Toponce]

On Fri, Aug 15, 2014 at 09:16:52AM -0600, Luke Jenkins wrote:
> The frequency we have for the repeater is very noisy as it is used by cable
> tv; this limits the effective range of the repeater since the noise floor
> is so high anywhere that has cable tv infrastructure (including campus).

What coax cable is used between the transmitter and the antenna?

[Luke Jenkins]

RG-8 of some flavor.

-Luke

[Aaron Toponce]

On Fri, Aug 15, 2014 at 09:53:11AM -0600, Luke Jenkins wrote:
> RG-8 of some flavor.

Is there possibility of moving to LMR-400 or hardline? Possibly heliax? That
would greatly reduce loss. Also, how long is the transmission line? Sorry, I
haven't visited the site personally. :)

[Luke Jenkins]

The antenna is at the top of a 30' tower, the transmission line is about 40' long in total.

Moving to LMR-400 would take the loss from somewhere around 1.6db down to about 0.6db. Taking the effective radiated power from about 34w up to about 44w.

-Luke

[Aaron Toponce]

On Fri, Aug 15, 2014 at 10:00:23AM -0600, Luke Jenkins wrote:
> The antenna is at the top of a 30' tower, the transmission line is about
> 40' long in total.

$60 for 50':

http://www.amazon.com/LMR-400-Ultra-Cable-Connector-Black/dp/B0013REMTE

[Aaron Toponce]

On Fri, Aug 15, 2014 at 10:13:33AM -0600, Aaron Toponce wrote:
> http://www.amazon.com/LMR-400-Ultra-Cable-Connector-Black/dp/B0013REMTE

Although, I guess that's N male connectors, not PL-259, which I would guess is
the correct termination at the transmitter and antenna.

[Rob Eckel]

The cable has little to do with it. The cable tv channel doesn't help.

The main issue is the loss through the cavities, however. Next time
you're up there, hook one of the radios directly to the antenna
without the cavities, and operate the radio from the shack for a
little while, and you'll be able to hear what a difference the
cavities make.

Rob

Sent from my iPhone

[John Metcalf]

I initially used LMR-400 on the cavities and it did not perform well so we went back to RG-8. The antenna feedline, however, is LMR-400. Range is 'Ogden Proper'.

The noise floor is a big issue (squelch is up high) and also the transmit power is low (because of overheating issues).

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[John Metcalf]

I have a big technical data file that needs to go into a Google Drive or WSU data sharing site. Unfortunatly I can't access such services from my work laptop so I'll need to hand a CD to someone to do the rest of the work.

In the files there is configuration documentation, which may be useful for these types of discussions, ie."what kind of coax, antenna gain, etc.."

[Jeffrey Page]

I've been waiting for the big technical file, I'll take it.

Also, I have a new cooling fan for the transmitter, I just got occupied with a move and then flight week.

Jeffrey D Page

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[Aaron Toponce]

On Fri, Aug 15, 2014 at 10:29:53AM -0600, Rob Eckel wrote:
> The cable has little to do with it. The cable tv channel doesn't help.
>
> The main issue is the loss through the cavities, however. Next time
> you're up there, hook one of the radios directly to the antenna
> without the cavities, and operate the radio from the shack for a
> little while, and you'll be able to hear what a difference the
> cavities make.

Oh, I see. It shares a conduit with other coax cable, and they're all
interferring with each other?

[John Metcalf]

Datas

[Aaron Toponce]

On Fri, Aug 15, 2014 at 10:51:25AM -0600, John Metcalf wrote:
> I initially used LMR-400 on the cavities and it did not perform well so we
> went back to RG-8. The antenna feedline, however, is LMR-400. Range is
> 'Ogden Proper'.

Have you looked into 7/8" hardline? The solid copper shield should greatly
reduce outside noise. Pricey stuff, but might be worth looking into? Or maybe
we should just build a Faraday cage around the feedline. :)

[Jonathan Karras]

No other cable exists in the penetration out of the shack (outside of a now defunct CAT5 cable).

--

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Weber State University
801-626-7529

[Aaron Toponce]

On Fri, Aug 15, 2014 at 03:49:33PM -0600, Jonathan Karras wrote:
> No other cable exists in the penetration out of the shack (outside of a now
> defunct CAT5 cable).

I guess I need to take a visit.

[Rob Eckel]

My email earlier today probably wasn't clear as I tried to type a brief message from my phone.  Here's another attempt.

• Antenna feedline
  
• If I remember correctly, we used Davis RF Bury-FLEX
  
• It's a fairly high quality cable, for the price.  It's comparable to LMR-400 at our frequency.  Hardline is better, of course.
  
• Upgrading the cable will be an improvement, but it will probably be minor and only measurable with test equipment.
• Cable TV Interference
• Cable TV Channel 18 uses a video carrier at 145.25 MHz.  That's our transmit frequency from the repeater.
  
• Their RF is supposed to stay inside their cable, since they aren't licensed (Amateur radio is the primary service on that frequency)
• Despite that limitation, the cable network acts like an RF DDOS network, with practically every customer leaking RF from unterminated jacks.  Cable TV has been doing DDOS since before it was cool.
• Duplexer Cavities
• This is the black magic that is nearly universally responsible for difficulties in repeater RF performance.  Ask anyone who's built a repeater, and I almost guarantee they will say the duplexer cavities were the primary technical challenge.  If they didn't have any problems here, they either weren't on the amateur 2m band or they were located on a commercial tower and too busy dealing with intermod problems.
  
• Amateur 2m band frequency assignments for repeaters suck.  The tx/rx pairs are too close together.
• For anyone not familiar with the cavity setup, it's essentially two notch filters.
• On the output of the TX, the notch filter is tuned to attenuate the RX frequency. (144.65 MHz)
• On the input of the RX, the notch filter is tuned to attenuate the TX frequency. (145.25 MHz)
• There's two main problems for the receiver:
1. The TX is blasting out power concentrated around 145.25, and if it's not reduced down close to the noise floor on the input to the RX, it overloads the RX front end.  This causes receiver desensitization - it's like trying to listen to someone whispering to you when someone else is yelling in your ear.
   
2. Some of the TX power in it's sidebands invariably ends up in the RX channel, which reduces SNR on the RX frequency - compounded by the finite Q of the input filter resulting in attenuation on the RX frequency.  This is worse when the RX/TX pairs are closely spaced.  See my comment about 2m frequency assignments above.
• The duplexer problem becomes more difficult the closer the tx/rx channels are to each other.  Maybe difficult isn't the right word - expensive is a better term.  The filters need to be very high Q to attenuate the frequency you want to block while rolling off fast enough to avoid attenuating the frequency you want to pass.  High Q = large size/precision = High $.  Luke and John were able to scrounge some used cavities at a decent price from a swap meet, but they aren't the best quality (not terrible, just not great).  There are plans out there for DIY cavities, but even those aren't cheap unless you discount the value of the time you spend to build them.
• We had to compromise in tuning the cavities we had to work with originally.  To reduce the TX power at the input to the RX low enough to prevent desense, the attenuation at our RX frequency is higher than desirable.  This is the primary limitation to the range of the repeater, unless something has changed since.. 3 years ago? Time flies.
  

Rob

[Terrence MacArthur]

Not really a reply, but "reply" seems to be be the only way I can discover to post something.  I just got a 25 Watt handheld.  Made by Luiton.  Problem is the manual and the software itself provide no instructions on how to use the software to program the unit.   I need to either get it working or return it by September.  Anyone our there experienced enough to help me figure it out?

[John Metcalf]

Hi Terrance and welcome!

What is the model of the radio? 

Sent from my iPhone

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