Tag Archives: microwave

South Black Range SOTA and park activation on 13cm band – 15th June 2019

Having received an offer from Ted VK1BL to help me find and fix the problem in my 13cm transverter, I spent an evening with him on 13th June. Moving through the various functional blocks in the transverter we found

  • The receiver was working quite ok, it was very close to the right frequency and was fairly sensitive, hearing -120 dbm from the HP sig gen pretty well
  • The output from the PLO was good and at a level of +7 dbm as recommended for the mixer
  • The output from the sequencer board, which includes attenuators and a level setting control for the IF signal, 144 MHz in this case, was working well and we calibrated that at -10 dbm for input to the mixer, with 0.5w drive on 144 mhz from the ft817
  • The output from the mixer and filter was at the expected level, about -13 dbm
  • The output from the tx IF amplifier/driver was +10 dbm, which was adequate for the power amplifier
  • The power amplifier had the correct negative bias and positive voltage on the correct terminals
  • But the power output to the antenna socket was zero.
  • The power output from the amplifier (before the relay) was about +35 dbm (approx 2.5 watts)
  • The relay board was examined and was found that the DC to the relay coil was intermittent. Resoldering the pins of the relay, a surface mount type, fixed that intermittent and made it a reliable connection. The output to the antenna socket was then +35dbm or 2.5w.
  • Transverter considered fixed.

With that result I discussed the possibility of an activation on Saturday morning to prove it in the field. Andrew VK1AD offered to activate Mt Stromlo and I decided to visit South Black Range. Coincidentally it was the day when bonus points commenced for VK2 summits above 1200m, so I half expected to find some snow on the higher parts of this summit, as it had recently snowed down to about 900m.

No snow, quite cold at about 3 or 4C when I got there, but it warmed up to about 8C by midday.

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FT817 in foreground, transverters and tripod holding 1296 yagi at rear

After initial contacts on 144 then 1296 we switched over to 2403 MHz and found we were able to make easy contact, my signal received a 5×8 report from VK1AD and I received his signal at an indicated strength 5.

Note: the distance of this contact was about 47.5 km, not bad for 2.5 watt transmitters. The locators of the two summits are QF44MQ (Stromlo) and QF44SN. The visual horizon is 35km so this is beyond “line of sight”. But how far over line of sight is it?

According to my iphone app DistBear the distance between centres of the two grid subsquares is 47.5km. So 2.4 GHz worked fine, well over the visual horizon. To get a more accurate distance I used the website https://sotamaps.org, using the “range mapping” option, we get a more accurate measure of the distance, at 48.7 km. I am sure there will be longer contacts made on this band using the same equipment.

The antenna in use for 2.4 GHz at my end is shown in the photo below attached directly to the 2.4 ghz transverter, was the SG-LAB PCB antenna, a 2 element HB9CV type on loan from Andrew VK1AD. The 2403 MHZ equipment was placed on a rock and turned so that the antenna pointed roughly towards Mt Stromlo, albeit through many trees nearby.

Two UHF transverters
The SG Lab transverter for 1296 is shown here sitting on the box containing the home made transverter for 2.4 ghz. These two transverters are, ironically, equivalent in power output and receiver function though they operate on different bands.

After completing the contact on 2.4 GHz I moved to HF and ran a few contacts on 7023 khz using the Pixie half watt morse transceiver (on a 50 x 50 mm PCB), then moved to the KX3 radio and ran contacts on 40m and 80m SSB and CW. I left the summit just after 12 noon, after spending 2 hours there. The temperature had risen to 8C by then.

Pixie PCB transceiver, battery, key, ATU, balun

VHF/UHF Field day (contests) scoring proposal

After discussion for several months a proposal has been published for revision of the scoring rules for Australian/WIA-sponsored VHF/UHF Field Day contests.

The proposal is here:  vk1da.net/vhffielddayrules.html

A survey of active VHF/UHF amateurs seeking views on the proposal and other aspects of these events is here:  vk1da.net/survey/index.php

The proposal was developed by a group of interested radio amateurs, primarily Colin VK5DK and myself but in consultation with a number of others.

VK9NA expedition

Late comments about the VK9NA expedition I joined in January 2011.  This was a VHF/UHF/microwave and 2m EME operation.  Due to quite poor conditions for tropo across to the mainland, we eventually did most of the operation on 2m EME.  However we did try to make contacts and ran a lot of CQs on 144 MHz every day.  We did make some contacts but there were nowhere near the number of tropo contacts made last year.  The 144 MHz band was the main band used for this work.

We activated the station every day on 6m as well, from the hotel site.

Due to the high winds experienced on the hill we moved the EME station to the Guide Hall where we had been kindly offered the use of the grounds.

On Norfolk the internet access is provided by Wifi connections at hotels/resorts and a few in the Burnt Pine business area. I found it was necessary to buy several different cards to get access via NIDS, Norfolk telecom and another account for access at the hotel I stayed at. Wifi access from Mt Pitt was good, from the hotel the others stayed at, access to NIDS was not good.

The radio conditions on vhf up were not as good as they had been in 2010. This was partly due to physical weather conditions, including strong winds for the duration of the operation from 8th to 20th January. On the weekend of the summer field day conditions were very poor and the only contacts made with the mainland that weekend were on 6m, and there were not many of them.

The 2m EME operation was very successful.  Over a hundred contacts were made using JT65 via the FT897 and a laptop computer running the WSJT software.  A TE systems amplifier boosted the output power of the FT897 for EME work.  The list of stations worked is at the VK9NA website.

I greatly enjoyed the event.  I learned how to use WSJT on both FSK441 and JT65B, and learned a bit about pointing a very large 2m antenna (19 elements, 12 metres length) at the moon and periodically repointing it. For about half or more of the time, the moon was not visible so we were relying on compass bearings corrected for mag offset/declination and an inclinometer for the elevation.

I also became familiar with the FT897 and found what a great radio it is for this kind of operation. The other radios used were FT817 and a TS2000 which I found to be a very good radio too.

The TS2000 has an option to automatically transmit CW at a 700 hz offset (actually the offset equals your selected cw beat note and sidetone frequency) when you switch from USB to CW. It also has an option to automatically switch from SSB to CW mode if you press the key, whether it’s an automatic key or a hand key. Very neat.

Apart from the radio aspects it was also great to get to know Michael VK3KH, Alan VK3XPD, Kevin VK4UH. We were fortunate in being well organised on the social and meals front by Michael’s wife Roz and her sister Gail, and Alan’s wife Aileen all of whom made this event that much more enjoyable.

We did attend a few local special events such as the fish fry, the progressive dinner and the re-enactment drama based on the voyage of the Bounty, the eventual mutiny led by Fletcher Christian and the exile of the mutineers at Pitcairn Island. This history is a proud aspect of the Norfolk Island culture today.

A great event and a fun filled 10 day trip for me.

Here are some photos at Flickr:

Here is one photo of the EME antenna.  Remember  it is 12 metres long.  There are 19 elements.  Click the photo for a larger view. The long “element” in the centre of the boom is just a truss boom – the antenna has vertical and horizontal stabilisation to prevent it flexing and losing gain. EME antenna at VK9NA

2010 Spring VHF/UHF Field day on 7 bands

For this event I took my usual station on 50 to 1296 MHz, plus my transverter and gridpack for 2403 MHz, Ted VK1BL’s transverter and gridpack for 3400 and Dale VK1DSH’s 10 GHz station (IC202, transverter, dish and tripod).

Contacts were made on all these bands.

Performance of the station on 1296 MHz was not as good as in previous years.  This may be due to conditions, or to a problem with my antenna or my location on Mt Ginini.  It is becoming increasingly more difficult to find suitable places where even two required directions are not partly blocked by the trees on that mountain.

Some pictures are already on http://www.flickr.com/photos/exposite/sets and I’ll be putting some also onto the vk1da.net photo pages.

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Spring field day a wipeout for me

After lugging all my equipment for 50, 144, 432, 1296, 2400 and 3400 MHz from the car to the north side of the summit at Mt Ginini, it still took several hours to get set up and operational. I finally got on the air on all bands at around 6pm, after making some earlier contacts on 1296, 2400 and 3400 with VK1BL and VK2AES.

Later I made contacts were made with VK1BL/p and VK2AES/p on all six bands (3400 only with VK1BL) but conditions and activity from further afield seemed quite poor with only weak signals from a small number of other portable stations.

I was running my station from a newly purchased inverter generator.  This was not a name brand but an import sold by a Victorian dealer, mostly marketed via Ebay.  I was pleased that its noise performance was much better than my previous generator.  However at about 9pm on Saturday night, within 20 minutes have having its fuel topped up, it slowly ran down and stopped.  All efforts to get it going again were unsuccessful.  I SMSd the other local field stations telling them I had a power problem.  The next morning I could only pack everything up and go home.

What happens to the generator has not been resolved yet.  My confidence in this particular unit is zero.  I have not been able to restart it, despite following the advice of the dealer and changing the fuel to premium unleaded.  I can believe it would run better, but I don’t see why it would simply fail to restart on ordinary unleaded.

I did examine the spark plug and found it was fouled considerably.  The recoil starter still reveals compression is good so I don’t think the rings have given up.  I suspect ignition circuit failure.

Fortunately others didn’t have this problem and went on to make more contacts.  The contacts with Doug 4OE did not work out too well, with Ted VK1BL making only marginal contacts on 144.  Contacts on higher bands were not possible.   Conditions were simply too poor.

Better luck next time.

2.4 GHz transverter success

The 2.4 GHz transverter has been completed and I used it in the vhf/uhf field day on the weekend of 15/16 November.

Construction began on Sunday 9 November with the first components soldered onto the sequencer board, finishing on Friday 14th November when I finally measured the transmitter output power.

The next day I was on Mt Ginini, with a 24 db gridpack dish (obtained from The RF Shop) attached to the transverter, receiving a big signal from Ted VK1BL at Mt Coree.  I replied to his call and asked how he was hearing me.  He replied immediately! This was my first contact on 2.4 GHz, made all the sweeter by the knowledge that the transverter was home made.

Together with some other “firsts” on this field day, it made for a very good weekend.

I have written up the details of the design and construction and submitted it as an article for AR magazine.  The article was published in July 2009 and can be found in the AR archives here.

The 13cm transverter under test
The 13cm transverter under test