VK Logger Ham Radio Forum Archive

Digital Modes Please Admin

David

The CW illiterates won't get the significance of the .... .. But the format that you have suggested is a very good one.
Congratulations.

David

I would like to see ALL beacons GPS locked and run a continuous WSPR format with the Tx frequency on the published one. Most stations who are serious about propagation run a computer in the shack and it is quite simple to run the WSPR program while doing other things. I run two additional monitors o...

It also says
Note 10: 50.0 MHz to 50.1 MHz segment may be used for
NB Data communication with overseas stations

David

You also need to be aware that most (all) 50 MHz yagis have more gain off the back than out the front when used at this frequency.

David

The savvy amateur doesn't use lossy RG58 to make baluns at VHF.

David

I have done some actual measurements on both 6 metres and 2 metres, On 6 Metres I measured around 5.5 db improvement at a take off angle of around 8 degrees with the antenna at a height of 8 metres. This was done using W7GJ off the moon with my 15 element yagi. This agreed fairly well with the EZNEC...

Oils ain't oils, and neither is plastic insulation tape. You only get what you pay for and if you buy cheap tape it doesn't stand up to UV for very long. I have found however, that 3M brand tape is very good and if you take care applying it with plenty of tension, it lasts a long time.

David

Might I enquire , what is the design of the antenna in question?

If you are trying to work MS, short calls are imperative. Time is of the essence. Just call "CQ VK4WDM" Don't repeat anything. Pause for 3 seconds between calls. Beam headings don't seem to be critical on MS. For other modes a 3 x 3 call is probably better, repeated after a longer pause. D...

If you keep an eye on http://www.ips.gov.au/Satellite/2/1/5 you might get an idea of what is happening.
David

There used to be a general consensus that the optimum trade off between gain and sidelobes happened at -13 db sidelobes. This happens when the stacking gain is around 2.8 db. If you go wider for more gain, the side lobes come up. If you go closer, the first side lobes go down, gain goes down and sec...

I don't always agree with Steve, but in this case I do. For one thing, the stacking distance, even for small yagis on six metres has to be at least 6 metres and for the 10 element YU7EF which I have, the optimum distance is almost 8. Secondly, if you start with a beam which has a nice clean pattern,...

I am not sure whether anyone else has made the point, but at 432 MHz most commonly available (read cheap) SWR meters only give a very rough approximation to the truth. It isn't hard to make a slotted line at that frequency with a suitable probe. Everyone who builds antennas above 300 MHz should have...

No one has mentioned the elephant in the room. If you have a lossy feedline you will get a fairly good measured SWR regardless of what you hang on the end of it. And it won't change much with variations in the frequency. Although changing the length of the feedline won't change the SWR of the antenn...

You should only get bad interference if there is a spark or a bad leak such as a piece of grass or a weed etc. Get a portable radio and go along the whole length of the wire, you might find a noisy insulator. The noise blankers on most of the modern day rigs seem to cope fairly well with this type o...

Has anyone thought of bending the heatsink to fit the module. The photo I saw of the heatsinh was just a 1 cm thick piece of aluminium. It wouldn't take to much force to bend that. In adittion you could put saw cuts a few cm apart to help both the bending process as well as increasing the area avail...

The problem with 6M is that it isn't all multihop F2. There is generally a bit of Es as well which combines with the bubble of F layer across the equator' The bubble gets the VK4's into JA but us poor southerners need a bit of Es to help us. This shows up as propagation to the VK4 beacons from VK3 w...

I would be very sceptical about any claims made for Chinese tubes. My searching has failed to find any tubes which measure up to the original Cetron 572Bs. The Russian ones are not particularly well thought of either.
David

Another red herring is the fact that signals do not always follow the the direct great circle route. Back in thE late sixties on 10 metres I often worked into Sweden from Northern VK8 while beaming due north. The great circle bearing was about 30 degrees west of north. I suspect that a tilt of the r...