VK7RTC - Mt.Wellington Repeater

[VK7HH]

Hi All,
A new repeater has been installed onto Mt.Wellington - Southern Tasmania near Hobart.

The callsign is VK7RTC
Frequencies:
439.825MHz Output
434.825MHz Input
Tone 123Hz.

It would be appreciated if during ducting openings to Tasmania if you can try this repeater out. ZL stations are of particular interest too.

Thanks, regards.
Hayden VK7HA

[VK7HDX]

Hello Hayden...Hopefully it has a large (non-ducting) footprint too. I will have a TX from in and around L'ton today (Saturday).
73...Karl
VK7HDX

[VK7HH]

No worries Karl.

Try giving it a go from home too if you can. A bounce off Ben Lomond may work too.

Hayden

[VK4TIM]

Hi Hayden,

The only issue for ZLs is that the frequencies above 439.800 are used exclusively for the National System, and 439.825 is one of the commonly used frequencies.
Given the site, I'm sure it will be heard easily on the mainland.

[VK7HH]

Hi Tim.
Thanks for that. I've never quite understood ZL band plans. I did see that there was a repeater with the same frequency on the South? Island. So I guess any users of that may be heard, assuming they use the same tone too.

Thanks
Hayden

[VK3BQ]

Hayden.

Curious why 123Hz and not 91.5Hz tone?

which seems to be the defecto national standard these days. ??

[VK7HH]

We have various repeaters in Tasmania that are 123Hz. We have never had any of the false decoding problems encountered in VK3.

I did trial 91.5Hz on one of our repeaters but got a funny mix with the receiver which caused an audible hum on a received signal. A change to 123Hz fixed that.

[VK6LD]

We have various repeaters in Tasmania that are 123Hz. We have never had any of the false decoding problems encountered in VK3.

Same here in VK6. It must be something in the water in VK2/3/4.

On a serious note, VK6 was never invited or had a chance to comment on the shift from 123Hz to 91.5Hz as the standard tone. Not sure how that could happen.

It does cause some angst to interstate travellers unless they have access to the internet or up to date callbook for their travels.

Cheers,

Rob...
VK6LD

[VK7JG]

Good work Hayden.

The problem we will have if we all use the same CTCSS tone of 91.5 is that in our case take VK7RAA ,147Mhz on Mt Barrow shares the same frequency as RGL and we will be back to our mutual interference when band conditions support propagation across the Strait . If and when we install CTCSS on VK7RAA it will definitely not be on 91.5Hz.

Also whoever came up with 91..5 did not take into account that it is not a frequency selectable when using AWA RT85 transceivers in their standard form .

123Hz was originally selected as it was an easy number to remember .

Regards.
Joe
VK7JG

[VK7HH]

Hi Joe.
Thanks. Can you access from home, or are you still down this way? If so I'm listening at work all day.

VK7RAA has that unique problem with 3RGL, one which I don't think would happen as often down here. Although I do enjoy hearing VK3's. I'd like them to try VK7RTC when the band opens (now).

Dion 7DB has a good system, running dual tone decode on VK7RMD. This way VK3's with a single 91.5Hz tone encoder installed into their radios can access it from the mainland. That said, I'm sure most these days have modern radios which are selectable tones.

Regards
Hayden

[VK3BA]

Good work, Hayden and anyone else involved

Cheers,

[VK7DB]

Thanks

[VK4TIM]

Hi Tim.
Thanks for that. I've never quite understood ZL band plans. I did see that there was a repeater with the same frequency on the South? Island. So I guess any users of that may be heard, assuming they use the same tone too.

Thanks
Hayden

G'day Hayden,

In ZL the band 433.000 to 434.775 is used for either repeater inputs OR outputs. There are plenty of reversed (user TX high, RX low) 70cm repeaters in ZL, and the band 438.000 to 439.775 is used for either repeater outputs OR inputs.

The bands 434.800 to 435.000 and 439.800 to 440.000 MHz are exclusively used for the National System.

The channels 434.800, 434.850, 434.900 and 439.950 are used for "so called reverse offset" repeaters, most often as intermediate link repeaters, while 434.825, 434.875, 439.925 and 439.975 are used for "normal" negative (user TX low and RX high) repeaters, often the main "node" repeaters.

CTCSS is not used on any of these National System repeaters, as the extra delays in CTCSS decoding, when added from one end of a network to the other (which could be 10 hops or so) would cause words to be cut off, as they operate in something akin to a "daisy chain".
I have had significant involvement with this network when it was re-engineered in about 2004 or so to overcome the interference problems, and was also a trustee of the Klondyke site, serving Auckland and the northern Waikato, until 2007.

Other, independant repeaters must operate with the same TX/RX offset in the areas served by a given "inverted" link repeater, especially where they are co-sited.
Other independant UHF repeaters are allocated "inverted" repeater pairs as required, if LIPD interference is an issue, such as in more densely populated areas.
LIPDs are not taken into account when repeater frequencies are selected, as they have no protection from interference.

As for CTCSS tones on repeaters, there's some good sense in using different tones on repeaters, rather than using the same tone nationwide. Higher tones also do decode slightly faster. There's no ACMA or WIA mandate to use a specific tone, it's not a licence condition to use either 91.5 or 123 Hz, so you could use anything you like. Modern equipment can generate all standard tones, so as long as it's documented, no problems.

[VK2AAH]

The thought of carrier operated links gives me the shudders Tim... it makes me think that noise in New Zealand is not the issue it is over here (probably explains why some NZ equipment is sold with totally inadequate internal duplexers- they seem surprised when the gear curls up its toes over here).

Why don't they just run these links hot and use in-band signalling for fast key up? It has to be better than running carrier switched...

Cheers

Richard

[VK4TIM]

Richard,

Yes, the "links" are simple repeaters, with no tail, and yes, use carrier squelch. Hmmmm. Noise floor can be a problem on some sites.

Main sites may use a main frequency of say 439.875, for local access, and "links" with TX frequencies like 439.850 and 439.900. The intermediate step is the "link" repeater, RX high and TX low.
Crude, yes, but with some careful engineering, it does work. Any interference received at any stage is heard through every site. With transmitters operating that closely at one site, (albeit on separate antennas, the links are yagis) you need to make sure you use low intermod, preferably stainless antennas that have all joints welded to prevent intermod.....

If the links stayed up 24/7 as hot links, then the intermediate link repeater would also stay up as it would have a signal on it's input, which could come from the main sites, and local users would not be able to access.
There were grand plans to install digital links in both the 23cm and 12cm bands, however things like the resource management act prevented the installation of dish antennas on towers without high application costs and politics.
Also in one case, there wasn't the physical space to allow the installation of a dish antenna at one site.

Simply put, the greenies won't allow you to install an antenna on your site without first consulting them (and local councils) and doing environmental impact studies etc.. Silly politics.

As for some gear not performing well in the filtering department, tell me about it. The cheap chinese gear is probably worse, using notch-notch duplexers. Not on my site. No way.

Also I refuse to allow class licence equipment on my sites, they're not on the register of radio frequencies, and often the gear is less than clean spectrally, and not protected from interference. The operators of that sort of gear seem to think that they have more rights to clean, interference free operation, than anyone else, and make the loudest noise when problems occur.

[VK2AAH]

Interesting challenge Tim... I've spoken to Dave at Tait in Christchurch a couple of times about the network when I was there- I'd love to see something like that here.

Cheers

Richard
VK2AAh

[VK4TIM]

Ah, yes, the guys at Tait. I used to know a few othe the engineers and system people, including Eion Gibson, (SK, ZL3AG I think).

I started at the Tait factory in 1991.

Would be interesting to do a linked multi-site system here, however it would not be likely to be analog, but maybe DMR, P25 or other digital technology. I'd love to have a crack at it on 1200 MHz, especially in the main cities...

[VK7HH]

I suppose our system is quite small to theirs.

At one point we had, 5 repeaters all linked up in VK7. You could talk from the tip of the North West to the far South East.
The linking methods use a variety of CTCSS switching etc.

Hayden