Author Archives: VK6LD

Equipment Check day – Sunday June 23rd – all welcome

WARG will be hosting a “Check your equipment” day at our usual venue, Peter Hughes Scout Communications Centre, on Sunday 23 June 2013, starting at 11am.

The purpose of the “Check your equipment” day is an opportunity for Amateurs to bring along their own equipment to be tested using professional-quality calibrated instruments.
Testing will focus on the usual RF parameters, so if you are wondering about your rig’s deviation or modulation limits, S Meter accuracy, receiver sensitivity or the like, now you can find out for sure. Likewise your other station equipment – whether your SWR-Power meter reads correctly, or your dummy load is a good 50 ohm match on all the bands; and so on.

WARG will supply professional quality test equipment and knowledgeable people to drive it. We will also provide the usual 13.8V DC and mains AC power supplies

You will need to bring your equipment, and all accessories required for it to operate on test,like the power cables, microphone, and any other specialist items. If you’re bringing one or more handhelds, ensure the batteries are well charged.

We’ll be set up to fully check equipment operating from 160m through to 70cm, mainly in analogue-based modes, such as SSB or CW, and FM, and RF power levels from QRP to the legal limit.

We will be able to check function and basic accuracy of RF power and SWR meters, and impedance match and frequency response of dummy loads or RF filters. We can also do resonance sweeps of some VHF/ UHF antennas, .

We may be able to test other things … if you aren’t sure, bring it along! As long as it can be safely powered up on the bench, we can advise on the day. Or if you can offer to test certain equipment, please let us know.

For each item tested we will give you a written summary sheet, outlining performance.

Note that we won’t be geared up to to repair or realign equipment – but we will be happy to give advice if we find anything amiss. (If anyone wants to consider working on their own gear, there may be a corner available – but BYO tools and everything…!)

Cost of all this is only a gold coin donation per tested item (depending on how many bands you want tested – thorough tests of multiband/mode rigs will take longer, and will thus warrant additional donation). WARG members – or those who join WARG on the day – can have some items tested free. (WARG membership is still only $25.00).

With events like the RD contest and Hamfest not far away, June 23rd is a good opportunity to put your gear through its paces

The equipment check day will start around 11 am, and we need to be packed up by around 4 pm. A sausage-sizzle lunch, soft drinks, tea and coffee and afternoon snacks will be available, all at reasonable prices, Funds raised will go into keeping our repeaters on the air

We would appreciate RSVP, for catering purposes, and also to get an idea of how much equipment we have to test. Also we are looking for volunteers to help on the day – whether you have professional-grade radio comms test setup you can bring – or are willing to help on the day, cooking the sausage sizzle etc, all assistance would be appreciated.

Email us through the Contact Page, or call in to our on-air net, Sundays at 10:30 local on VK6RLM, 146.750.

So, we hope to see you at WARG’s “Check Your Equipment” day, June 23rd, Sunday, 11am to 4pm, Peter Hughes Scout Communications Centre, corner Gibbs St and Welshpool Rd East Cannington.

BR & 73,
Anthony VK6AXB

Roleystone Working Bee – 26 October

Hello All,

Anthony here, quick update on today’s work at Roleystone.

The UHF repeater VK6RUF was found to have almost no output power (no doubt the cause of the poor performance) and was removed, I have the transceiver for repair and will reinstate as soon as fixed, hopefully later this week.

Other antennas were checked and the 2m repeater & diplexer/cavities spec-checked to try & correct the intermittent noise problem. (One suspect coax connector was replaced, we should continue to monitor the repeater performance to see if any improvement). The 6m voice repeater was also checked, all looks OK.

The batteries were removed, cleaned and refitted, allowing timber reinforcing to be placed underneath (not quite enough timber for the whole set, job will be completed next time). The DC system was checked and the power supplies readjusted to compensate for voltage drop (due to diodes in series), so the battery/system
voltage is ~13.6V.

Some of the cells are starting to show signs of age, and while we can probably count on another year or two from these, we need to start looking around for replacements – the existing ones are sealed gel types, heavy duty, around 500AH per cell – if anyone can find some disposal ones like these in reasonable condition, we
are definitely interested! (If the price is right…)

More work is planned in November (date TBA) including the packet system overhaul, Bob VK6ZRT has volunteered his expertise to carry out this work (and hopefully train a few others of us in the ongoing care & feeding of VK6BBR).

Thanks to all who attended today: William VK6KWT, Cliff VK6LZ, Andrew VK6VCG, Matthew VK6KMC, Dennis VK6KAD, Jim VK6JIM, Anthony VK6AXB. My apologies if I have forgotten to mention anyone, all efforts are sincerely appreciated.

BR & 73,
Anthony VK6AXB.

Official Opening – D-Star Repeater VK6RWN – 18 October 2008

Hi All, Saturday, 18th of October 2008 is the DSTAR release presentation for VK6.

It will be held at the Darling Range RSL Hall, 35 Canning Road, Kalamunda, starting from 11.00am. (See map below for directions)

There will be a presentation from Icom representatives and then a practical demonstration.? They will also be available for questions and assistance so please make sure you bring your DSTAR radios along.

We will be having a sausage sizzle for lunch and John Tower will be there with some DSTAR equipment for sale!

Please come along, it will be good to see you all there.

Please pass this e-mail onto anyone that would be interested.

For further information please contact myself, VK6FZUK on 0414 533 244.

Regards, Danny Ainsworth – VK6FZUK.

googlemap

Tic Hill Site Visit

Hi All

A maintenance visit to tic hill (Redhill) VK6RTH was carried out today, (08.05.08)? mainly to check on the electrolyte levels in the 2 volt wet cells and general visual of the site.

This was carried out by Bob VK6POP(with 4 x 4 vehicle) and myself.

As usual we were escorted through the Quarry (mine site) by the site owners (Hansons), although they were busy at the time. They appreciated the Cake for morning tea which we leave as a thank you for their assistance.

Bob topped up the large wet cells with distilled water which had gone down by a about a third (in the min/max safety area)in each cell since October 07, this took approx 1 litre each, and cleaned the terminals
which showed signs of salt build up.

I checked the SWR on the Antennae cables (70 cm = 1.4/1 and 2m 1.3/1) which appear to use the dual bander. The Digipeater could not be checked as we did not have a BNC connector for the Antenna Analyser with us.

I am mystified as to what exactly is on the Tower(s) for example what is the dish? and square box half way up the main tower for ? is it wifi and whose is it?

I know about the 4 x 4 club receiver and LIPD Xmitter which appears to be working (we also topped up their wet cells).

There are also three unused co-axes – one open circuit and two with reasonable SWR.

The Solar cells were feeding 5 Amps during bright sun. The batteries each showed 2.2 Volts.

A visual check of the tower did not show up any problems. The water leak repair to the “Bunker” last October seems to have held with no evidence of water.

73 Cliff VK6LZ (Site Manager)

Walliston Tower Configuration

Hello all,

Attached is a concept for the very important antenna installation on the Walliston tower. There may be another concept idea but I have not seen such as of yet. So to kick things off please have a read and comment.

Will
VK6UU

Walliston RF concept

 

Will VK6UU

The antenna layout on the Walliston tower can be designed in several different ways, each with its own pros and cons.

The concept presented here relies on separate antennas for each band and split antennas, i.e. separate antennas for receive and transmit, except for the 70cm digital repeater and the simplex 23cm high data rate gateway.

This design is expensive in that it uses more antennas (8) and more coax (8) and hence takes up more mast space, but most important offers several important advantages.

Antenna failure.

Antenna failure, replacement and testing only takes out one repeater. If a triband or dualband antenna fails for example it affects 3 repeater systems. Antennas can be easily isolated tested and replaced.

Desense isolation

Easier to achieve desense isolation with less reliance on duplexer performance. Good duplexer performance is difficult to achieve particularly on 2M. 70cm duplexers are cheap and don?t require as much isolation as 2M duplexers. 23cm duplexers are difficult to source. The antenna layout highlights this with only the 70cm repeater using a duplexer into a single antenna.

Below is a concept diagram of the Walliston site. It shows the antenna mast, which is 75? (23M) high along with the layout of the antennas. Yes there are a lot of antennas and yes there is more than one way to put together the antenna layout. The number of antennas could be reduced. This design uses split antennas on all systems except the 70CM digital repeater and the 23CM high-speed digital simplex system.

Split Antennas

Split antennas means one for receive and one for transmit for each duplex repeater, rather than a duplexer feeding one antenna. This offers one major advantage, less filter isolation is required (cavity filters) and zero desensing is much easier to achieve.

What type of antenna to use?

Folded dipoles and in particular the ones you see on commercial installations are cheap, broadband, DC earthed for lightning protection, low SWR (1.2 or better), robust, come in a wide frequency range, can be custom made if required (e.g. 23cm) and can be stacked (more than one) to produce increased gain. And these antennas are designed to work side mounted on a tower, which is the type of installation we are looking at. Side mounting also produces 3dB gain, which is ideal, as the Walliston site should direct most of the signals to the West.

VHF Folded Dipole

Variations

Due to the number of antennas and the number of coaxes required in this design there are some options to reduce this. For example the 2M receiving dipoles (2 of) could be phased together (3dB gain) connected to one coax and then split via a low gain RF amp at the bottom of the tower, giving two antenna feeds. Or only one dipole could be used (to save antenna space) and split as described.

The 4-dipole arrays on 23cm and 70cm could be reduced to 2 dipole arrays. It all depends on what the tower can support.

The diagram is only roughly to size but a to scale diagram can be produced to give us a better idea of the antenna space taken.

Suggested Tower Config

Walliston tower configuration

I hope this document encourages discussion and more ideas. The antenna installation is one important (if not the most important) aspect of this complex installation. If we wish to achieve the very best performance RF wise then considerable engineering excellence needs to be our number one goal.

D-Star Progress/Update – 16 April 2008

On the subject of progress on my DStar commitments: the 400AH battery bank is OK & on charge, but difficult for me to do much more (ie: arrange support racking/battery straps & cables/DC distribution system) until we agree where & how the batteries are to be housed in relation to the equipment. Mains power supply is tested & working OK, I plan some preventive work to improve its reliability, and modify to add dry-contact alarm outputs (to signal mains failure/low voltage etc).

70cm diplexer still needs a fair bit of work, but should be straightforward. 23cm iplexer is still an unknown quantity – although I have an offer of assistance I am yet to follow up properly, but aim to do so soon.

BR & 73,
Anthony VK6AXB.