Moonbounce on 1296

[VK2JDS]

More time has passed , just today Phil vk4cdi worked some americans, a japanese station and myself. His station with a 3.7 metre dish is really working well . and thats just the start of the pass, later tonight europe will open up and the hb9q 1296 logger has a full board of waiting european operators. get yourself a dish and get going on the microwave bands.
today i removed the 60 watt amp and installed the 160 watt amp out into the box on the back of the dish, its only running about 90 to 100 watts but the return echos are clearly audible and bright white traces on the spectrum display. The added choke ring onto the septum feed does seem to better illuminate the C band dish i have here.
the weekend 5th 6th and 7th will see us attempting Brazil on 13cm . Matt vk2dag is bringing his 13cm transverter and PA out and installing it on the dish again here for a sked with Bruce PY2BS. doppler will be difficult and its all cw on the higher bands. Bob vk0bp/vk2abp will be out to observe. Anyone else interested?
my 23cm high power permit application got approved, just waiting on the paperwork now. we now need to convince acma to allow high power permits for troppo long haul work
cheers all, hope to work you off the moon soon
73's de Dave vk2jds

[VK2JDS]

further progress
after blowing up the g4ddk vlna a few times and more spare parts on the way, keeping backup preamps is a priority.
the new incarnation of the G4DDK preamp now uses a MGF1404 gasfet and has been tested down to 0.15 dB.

if you have a G4DDK check this link for mods http://www.vhfdx.ru/apparatura/rw3bp_12 ... timization
check this link for how to measure it http://www.vhfdx.ru/apparatura/accurate ... s_1296_mhz
here is part5 :http://www.vhfdx.ru/apparatura/1296-mhz ... ity-part-5

Its all about digging deeper into the noise to find those weak signals.

then there is the output power:
fitting the power amp out at the dish makes a huge difference, then I just changed the feedline from the back of the dish up to the septum from ldf4-50 to ldf5-50 and it gave a 20 watt power increase.
its a good option to mount the amp and switching gear at the bottom of the dish mount , but best on the back of the dish itself if you can do it. Run serious hardline up to the septum as it wont be bent and twisted as the dish rotates and elevates, just use superflex heliax from the IC910h to the dish mounted box (or whatever you can get from field days etc)
run dc power to the dish mounted amp, preferably 24 volts to reduce current compared to 12 volts , or just run mains up there and have a switchmode supply with the amp.
i dont have mains power, so 24 volts and a 160 watt amp has worked out well.
73's all

[VK2JDS]

This past weekend saw 4 amateurs and a 'soon to be amateur' come out to the dish to activate the Orange and districts Amateur radio club callsign in the 160 metre transtasman ssb contest. 150 contacts later the contest ended and it was time to work some moonbounce!
We booted up the station the next day and were hearing good echos. For the first time listening to your own signal echoing off the moon is a awesome experience. The look on the face of the soon to be amateur John is worth describing :
I had briefly described to John what I was attempting to do , we could see no visible moon as it was so close to the sun. we used a digital elevation meter and a compass for alignment and i pressed the morse key and the sound coming out of the speaker said it all . He stood there with mouth open for about 15 seconds watching the echo on the spectran screen trying to take it all in. (gobsmacked)

The moon was down in the west and we were into the business end of the pass. After some calling we got JT65c contacts for the visitors into the Netherlands and England!. Smiles all round and the new fellers were really inspired to get cracking on their own stations. Matt vk2dag and Bob vk2abp have done all this before but it still brings a grin to our faces hearing such nice echos , but Steve vk2xde and Lindsay vk2amv were new to the dish here and took it all in.
A great weekend of radio indeed, wire aerial for 160 metres , to a 5metre on 23cm

background to this , while testing the setup and a new interface cable i had a switching malfunction and blew the back-end out of the G4DDK yet again... doh
always keep a stock of spare in and out fets for your preamps, that kept the station going after a fet swap. buy in spares from Sam G4DDK and he is happy to send some, I just got another spare vlna with the new mgf1404 mods. Next was a new(old-but refurbished) dish, 5 metre, for Matt vk2dag to collect. everything is a work in progress, not just the hardware , but the people who come out and have a go and get inspired
73's all de Dave vk2jds

[VK5APN]

Dave

Yes this column is an inspiration. To all those who have thought about it but struggle to start. Yes it is that easy.

Having got my feet wet on 2m with a 10ele YU7EF yagi (5mt boom length) and a DSE amp kit, worked 14 stations so far (JT65b). Google and Youtube my call for my home page and video. This is with no elevaion control. Soon to be rectified, to enable greater flexibility.

I too am looking higher in frequency. Have my eye on a 3m dish (at a very good amateur price - bonus). I think (hope) that is OK with the XYL (Oh and council ). I dare not produce a 5m one Hi Hi.

Make Google your friend. Some interesting sites for 1296 EME include

http://rvhfg.org/pdf/articles/29.doc (intro doc)

http://w7iuv.com/1296eme/7ftdish.htm (Pictorial progress on the cheap - love the "G" clamps)

The only Downside to this EME is that IT IS ADDICTIVE.

So BEWARE

Could imagine the wide open mouths when they heard the echo's. Yet to hear mine, but would be just like my first EME QSO. Pumped and over the moon - HI HI

Regards

Wayne VK5APN

[VK2GOM]

Hi Wayne,

What sort of power level were you running on 2m?

I have had a listen at the moon before, but yet to hear (or should that be see/decode) anything. My local noise is simply too high I think.

I think the record for 2m EME at the moment is something like a 5ele and 5W on 2m! Someone over in Scandanavia completed with one of the big gun stations.

73 - Rob VK2GOM / G0MOH

[VK2JDS]

Hi Wayne, 3metre with shadecloth over it , now tell the XYL thats called a shadehouse for plants !! hihi

hope you get it going soon , its great fun !

any questions please post up here and we will get it sorted

monday morning at 3 am i was up and operational on 1296.065, Israel was -28 through the fog and pouring rain , but no sign of the Belgian station I had a sked with
The Israeli has a 1.5m dish skirted to 2.3 metres and about 40 watts and septum feed. You will have great success with the 3 metre on 1296, and especially on 2.3/2.4 GHz etc
Well worth getting and installing. if its a polar mount then set the elevation to straight up and lock it at that. now use the polar tracking actuator to raise and lower the dish for elevation adjustment , and swing it around on the top of the pole for azimuth. works well

73's from Dave vk2jds

[VK5APN]

Rob

I'm using a DSE Amplifier Kit. As JT modes are harsh (continuous TX of tones etc) on the amp I run it about 80-100w out. I do have a fan ontop of the Heatsink blowing air down onto the amp. This comes on only when in TX. This is fed into some second hand RG213, about 14mts of it. Who knows if it was OK. No mast mount preamp, no GPS lock of the stock IC706MkII (not the G model - said like the TV ad for the yellow pages and the G-O-G-G-O-mobile)

I am lucky in that I do live in a rural township, about 6km (line of sight) from the urban sprawl. When the moon is setting (due to no elevation control here) on the good moon conditions, the time is in the early hours of the morning (1-4am). Most neighbours are in bed with no plasma's or PC's on. The nearest farms does not use electric fences (grapevine growers), so no noise there. Keep trying, as I think you will be pleasantly surprised. Best to pick a good moon weekend. There is a link to the moon condition calendar on my EME log book page. Best ones coming up are early and late Sept.

Dave

Yes having to out bid one of the neighbours to the guy who has the 3m dish to secure the purchase. Comes with mounting pole and actuator. Still in negotiation at the moment. But there is another one that I have my eye on as well, but that is still in the air. Being lazy here in getting the one already dismantled, Hee Hee.

Will keep you informed on the progress, fingers crossed. Well done on the contacts. Yep next to 2m (due to easy access to HPA's and easy build ant that have been computer designed), 23 cms would be the next populated band. According to others and to the word doc link in my last posting. But that may change as the HPA's are becoming easier to obtain as well as the TVRO's Dishes.

Regards

Wayne

[VK2JDS]

further update
we now have Mark vk2ams fully operational, Brett vk2cbd is operational receive-only and Wayne vk5apn is almost operational. As always Phil vk4cdi and Rex vk7mo are about there somewhere!
i am running the newest incarnation of g4ddk's vlna and same power thanks to vk3xpd's 160 watt amp.

conditions are great at the moment and the moon is clearly visible for easy tracking. upcoming weekends have some EME contests running so expect to see a dogpile of cw on the low end of the band around 1296.010 to 1296.025 at the western end of the moon pass each night. most of these cw stations are high powered with large dishes so they should be visible on spectran or specJT (in wsjt9) by yagi stations used to working terrestrial stuff. there might be some US cw activity around 017 or 020 at moonrise.

to keep up to date with what events are happening on EME think about subscribing to the moon-net reflector, its a great source of info, also check in at vk3um's site and grab the latest of Dougs software, also think about a DUBUS subscription, its the cutting edge of whats going on in europe for eme etc

73's de Dave

[VK5APN]

A QSO between a 25m and 10m dish.

Listen at 1:40 into the clip
http://www.youtube.com/watch?v=mRbS2xLI-GU



Regards

Wayne

[VK2JDS]

its been a while since this thread was updated

today in the HB9Q logger (HB9Q.CH) there were 6 VK amateurs. this is great to see, as the rest of the world is looking for us.
contacts into russia, ukraine and japan as well as some into VK were completed, using a 2.4metre solid dish and 45 watts by Ross VK2DVZ on his first go at moonbounce. (!!!!)

you can do this too.

the gear here has changed a bit : still the IC910h, with G4DDK LNA and VK3XPD 160w amp module, but more fine tuning of the RX feedpoint eliminating any hardline between the feed>TR relay(18GHz transco) and the sma input of the G4DDK, just adapters. check out Sam G4DDK's website.
the amp is mounted on the back of the dish with a short run of LD-F550 from the PA output up to the septum.

Brett VK2CBD has been doing some work on his transmit side of things and his signal has about doubled since experiments started. He has worked many dx stations now and is commencing work on a dish skirt to increase the diameter to 4 metres. he has a qsl.com webpage showing progress. its worth a look.
Mark VK2AMS is working a heap of dx with his skirted dish, I see stations he has just worked in the logger regularly. That dish work and valve PA is going well.
Phil VK4CDI is heading onwards towards a DXCC on 1296 the way he is going!
Ross VK2DVZ and his 2.4m solid dish with amp is off to a flying start, and if you wonder if 1296 EME is always this good? the answer is Yes.
73 de Dave vk2jds

[VK5PJ]

Dave and others,
I have also been working my way towards 23cm eme and have a 3.7m dish in storage for this purpose (no feed yet). I can not help wondering about the obsession with rings around feed on smaller dishes, surely the apature blocking caused by a dish feed ring would outway the advantages it might offer in return. It seems to be a common theme that people add what seems to be a large blockage to the front of their dish to combat some spill over but surely the reduction in the exposed dish surface is more of a concern with lost gain?

Appreciate any comments on this from the readers.

Peter, vk5pj

[VK4CDI]

GD all,
I have a 3.6Mx .34 f/D dish, and with an OK1DFC/septum feed/polarizer I am slightly under illuminating the dish. In reality it means I pick up less ground noise and sidelobes are less of a concern, hence a 'full size' choke ring is not needed. As you correctly point out Peter, the increased blockage would negate any gain increase.
According to the experts however, a dual mode feed like the RA3AQ for my f/D would probably give me a 1dB or so improvement. And according to VK3UM planner, adding a 50cm skirt would give me a 2db increase in sun noise......

My efforts will go into an RA3AQ feed, then maybe a skirt.
Unless anyone has a 6metre dish lying around.......

Phil VK4CDI

And well done Ross!
Great to see all the VK calls on the HB9Q logger.....

[VK2KRR]

I tend to agree Peter (PJ) about the choke ring on smaller dishes, and even on my 3.8m dish, the choke ring looked huge so I left it off and it works very well on terrestrial and EME, although its only horizontal polarity, worked Jan PA3FXB in about 5 mins on Tuesday and could hear the ON0EME beacon audible.
Thanks also to the VK2JDS tuned pre-amp

[VK2DVZ]

Hi all, pleased to be able to join in on the 23cm eme fun.

After having my dish in the air for about 25 years, I found that the mounting frame that the dish was attached to was showing too much deterioration due to dissimilar metals, coastal climate - read salt laden NE, SE winds.

I was planning to acquire a 3m or larger mesh dish and ground mount it, but my qth has far too many trees blocking my European window together with other position restraints on where a dish could be installed.

As my existing dish is about 6.5m above the ground, the EU takeoff is much more favorable, so the decision was made to run with it for eme purposes. There is a lot of blockage due to trees to the north for terrestrial use but as the system has worked very well over the years from my current and former location, why change it? Yes the thought of putting a 3m or 3.7m dish on my free standing tower was contemplated, but did not want it to blow down is severe weather/storms. Even a 2.4m solid dish, parked on the Zenith, can be concerning in big blows!

The original VE4MA feed - with choke ring - illuminated the .375 F/D solid dish beautifully. After researching the OK1DFC septum feed I found a combination that would suit my dish F/D, so built one and installed it. The feed horn mounted preamp is a Mini-kits 33dB unit mounted directly on the isolation relay and is fed via the coax using a bias tee. The received signal is fed into the shack into a old 23cm-2m down converter then directly into a 2m to 28MHZ down converter (both by SSB electronics) and then fed into the HF RECEIVE ONLY connector of my TS-2000X. (Impossible to squirt RF into the back end of the preamp using this method). An in line 10dB or so rotary attenuator helps calm the S meter after the ATTENUATOR on board the rig is activated. The S meter will now read correctly!

The VK2RSY 23cm beacon was used to initially calibrate my 28MHZ IF frequency to the equivalent 1296.420 on receive and the actual rig 1296.420 TX frequency also, prior to noting any discrepancies and saving a series of split memory frequencies into the rig. Upon rechecking using the Dural beacon, I find that there is never more that a few hundred cycles of frequency difference, due to temperature, mainly affecting the dual down converters - near enough for me.

The entire upgrade has taken quite a while, but had successful eme contacts yesterday. Thanks Ian VK3AXH for being my first 23cm eme contact. Thanks also to Dave VK2JDS for contact and words of encouragement.

[VK3DXE]

Great stuff Ross. Once I get my 2m station to where I want it, 23cm is next.

[VK2DVZ]

Here are a couple of photos of the upgrade in progress:

The first photo shows the radome that covers the septum, instead of trying to use a waterproof box to house the relay and preamp. The tower and support base are clearly visible. The radome comprise a 50 litre plastic office/kitchen tidy bin - made in Australia. It has now been painted, along with the choke ring and dish face.


The second photo shows my method if installing the isolation relay and preamp. A 150mm long teflon pre-terminated coax jumper is used to interface the FSJ4-50 receive cable to the preamp. The relay is energised for RX.The RX probe looks into a 50 ohm dummy load during TX. Also prior to TX, 12v is removed from the preamp which then places a short to ground on it's RX input port during TX. Power to the preamp is via the RX coax line, fed by a bias Tee.


The third photo shows the dish in use for eme.

[VK2KRR]

Looks great Ross, good stuff

[VK2DVZ]

Hi all,

With a just over 7 weeks of intermittent EME use, I am very pleased with the performance of my 2.4m dish with OK1DFC feed. The total performance appears to be exceeding my initial expectations for a small station setup.

Initial power at the feed was in the 30-35 watts range, and resulted in 30 contacts off the moon with that power, one of which was an SSB contact with OK1DFC. In recent times I have been using an SSPA that loafs along while providing 120 watts at the feed. I have been able to decode (sometimes hear) my own echos using the WSJT ECHO mode, at good strength and have also heard my own 'whistle' echo on SSB.

This morning using JT65C, I was able to work Mark VK2AMS off the moon for a total terrestrial distance of 5.3km, thanks to about 3.77kHz of Doppler shift . This must rank among the shorter distances achieved on 23cm EME.

I would recommend anyone that has modest power and a dish to consider giving digital EME a try - you may get hooked on the fun too!

I also look forward to trying out my upgraded system with circular polarization on terrestrial DX during the coming summer season, running higher power and improved receive gain compared to my last 25 or so years using the previous setup.

Good DX to all...

[VK2ZIW]

Hi guys,
Much is posted here on the RF side of things.

How do you point your dish accurately?

Does your rotator system track the moon?

73 - Alan VK2ZIW

[VK2DVZ]

Hi Alan,

How do you point your dish accurately?

Does your rotator system track the moon?

In may case I rely on the WSJT program (in JT65C mode) to tell me where the moon is.

As for AZ and EL control my station is completely manual in that I adjust my linear actuator to the EL and my rotator to AZ. The AZ has previously been lined up on the sun to ensure a known direction at a given time and was set to match the controller readout.
I used a cheap but accurate digital 'bevel box' (read digital protractor) to setup my actuators memories in 2.5 degree increments, horizontal being 0 deg and 90 deg being on the Zenith - much closer accuracy in EL is available by goggling the Up-Down controls - I have a printed table of memory and elevation settings for reference.

Both AZ and EL accuracy was verified by observing the correct position of the feed horn shadow onto the surface of my dish again at a given time, as depicted by the program.
Further verification of accuracy is determined by peaking sun noise measurement results. To date I am happy with the accuracy - but can't afford to get distracted for too long, as the moon is in constant steady motion...

Auto tracking would be good, but have not considered it necessary at this stage with my small dish. Large dishes require far greater pointing accuracy and auto tracking would be necessary.