General question about the WIFI amps and pushing them, how can operators tell they are being pushed to hard? Am I correct in thinking that they then generate additional side-bands especially at the low audio frequencies as they hit compression as in this effect typically seen on the satellite:-
I guess it is not just the WIFI amps but any amp that can do this.
Or am I mistaken in what I am thinking?
Adrian
I had a good look for it but unfortunately can not find it, I will continue to look for it in old back up files, if I find it I will send via PM or email etc.
Adrian
Gentlemen, I was joking !!!
At least for me, our hobby still is about wireless radio..
73s Peter
It is about wireless to me, but I bet it is possible to do and something that Amsat as a governing body could operate for schools and colleges if they wanted to show the technology, and my questions were actually genuine. How would you authenticate licenced operators?
I have not used echo-link, D-Star or any of the other web gateway systems as it has never appealed to me, (I hate DMR with a passion as it was part of my job at a radio dealer's) So I do not know how these system is controlled or policed from abuse over the Internet I have it in my mind a sort of timed token system to a particular IP address, but it's just a guess.
Actually sat here in front of SDR console on the Laptop, I bet it is possible with that software?
What may be a joke could have merit in some quarters to both boost the hobby and industry, just a thought. But I am also happy to be shot down.
Adrian
How would you stop unlicensed operators and abuse and like a transponder would it not generate noise up to the satellite?
Just wondering.
Adrian
But I had fun making it and will have more with the 2.4Ghz one I am machining now.
I even managed to get some brass bar!
Adrian
Is there any plans to reduce the beacon to 1M SR, that may be useful the wider bandwidth users and also have the benefit of reducing the average power consumption, even if only slightly that the transponder takes?
Adrian
Yes you did mention that in the link as well. It is also something I have done in the past with a signal generator and Schottky diode to listen to a signal outside of a receivers normal range.
To the original poster, to me it is a good idea to have your own downlink as:-
1) it's yours
2) Should be less latency then Internet based
3) May be fun to put together
4) build it portable enough and you could use it anywhere.
As to the point of monitoring ones own transmissions, it was good to notice that many have the gear to make the checks and where doing so before the satellite was live, I would surmise that many are old hands at satellite working. I was not, but thankfully had a Hackrf that works to 6GHz to hear my output directly.
What I was trying to suggest was that a dish, 10GHz LNB and say a SDR with software does not necessarily provide compliance with licence conditions.
But I thank you for the link to the 2.4GHz transmission test as I just decided to get two of the MMDS converters at £8.50 each that were mentioned by PA0P together with mod instructions.
Adrian
Not trying to be awkward here, but how many actually have a receiver to monitor the transmit frequency on 2.4GHz and not what have been rebroadcast through the satellite. To me that is what 7(6) means. It is correct in that QO-100 is not test gear, but the assumption is that if sounds clear through the satellite then it is OK on transmit. Although down at 2.4GHz who knows what spurious side-bands or image frequencies are being transmitted, they are going upwards so will not effect anyone, will they?????
There was an interesting read on QRZ at one time about a security camera effecting a 1.8GHz sat band,
https://forums.qrz.com/index.p…nterference-issue.659731/
and a pdf about the levels of interference
I wonder if we can do harm to systems on other satellites.
Adrian
I have an aluminium filter that was designed for above 23cms that I retuned, I was surprised it was aluminium as it was copper coated.
Aerial Facilities, as was, built their band pass filter systems from aluminium, some would have copper clad board top and bottom but the sides stayed aluminium. I used to work for them and build them many years ago.
I did a bit of web reading before I started and apparently the issue is not the necessary aluminium which will oxidise very quickly and protect it self to an extent but the fasteners that can be used in construction, Keeping away from stainless and some other metals seems to be the key, Zinc plated basic steel appears OK with aluminium.
But all in all it was easier to get hold of aluminium in block form, it is relativity easy to machine if not a little sticky on the tools, so my little milling machine could cope OK. The issue was how to solder connectors. I would love to be able to Nickel and then copper plate things like this but for the odd job it is not worth it. But what I have tried seems to work OK, time will tell.
I also use a retuned Block filter at 2.4GHz that was intended for LTE gear, that is also aluminium, but is silver coated, now that would cost a bit to do, but RF losses at the higher frequencies would probably be worth while for the manufacturer.
I did a simple comparative test with the MiniTiouner express I have, waiting for a time with just the beacon active and it improved the MER by 0.5/0.6 dB. The MER changing from 8.1 to 8.6/8.7. This is with a 1metre offset dish and standard unmodified LNB and POTY feed, I did have better at one point without a rain cover, but it gets it back to the same area again.
Not a great increase for the effort I know, but still happy with the filter at this end. I guess this small gain is due to the reduction in bandwidth to 12 MHz from the 22+ Mhz bandwidth of the tuner front end at these frequencies?
Adrian
Well I solved it almost as it was, I do not have enough brass rod to make the filter, the rods are 8mm'ish! But I did have a bit of 10mm rod which I drilled out and sweated/pushed/bashed small sleeves over the base of the aluminium, this allowed me to use the blowtorch to solder the connectors to the sleeves.
To say I am pleased with the results is an understatement, it may, or may not improve things on WB, nothing noted on NB as the filter is wider then the NB transponder, but a simple alignment and test on the speccy An shows it does what it says it should.
10dB per div vertical and 10MHz per div Horizontal.
The marker at 744MHz
Adrian
I used aluminium as I thought Galvanic corrosion would be an issue when I eventually mount outside in a box? Also lack of brass at the moment.
Adrian
Just a bit of an update whilst I decide on what is the best way to proceed!
Over the previous days I managed to mill out of a solid block of aluminium, the basic cavity for the ID filter block. Used some aluminium bar stock for the rods and fixed most of it together.
I am now contemplating how I attach connectors to the aluminium rods. I was thinking of trying to nickel and then copper plate the bottom sections of the rods so I could solder to them, not sure if that would work and i really do not want to be messing with acids.
So looking for some simple ideas at present?
Ideas gladly welcome.
Adrian
Thank you Robert and Peter.
Robert, I will make a note of .625, I was using 620 for the tests last night is there a frequency emerging for SSTV such as MMSSTV style?
Peter thanks for that, band width is well under 2.7KHz so for these modes I will stick to Digital or mixed if it gets busy.
I built myself a simple interface between PC and Radio unit and did some testing with KG-STV, but I am not sure if there are predetermined frequencies yet on the Satellite for various modes.
Searches for band plans bring back the usual chart CW, Narrow Digital, Digital, Mixed and SSB, but I have as yet not found a typical subdivision.
So whilst I used a clear area in Digital for my tests last night I would not like to upset anyone by using a spot allocated for something else?
Adrian
OK Mike I will leave as it is. I am not wanting to mess with a good antenna and I reckon I am doing well with 0.75 Watts to a 1 metre dish on NB. So it will be a case of do not touch.
I am sure mk2, mk3 etc feeds will follow eventually, if so I will make one at the time, all that information not a lot to me i will have to understand smith charts first.
Slightly off topic, but on webchats. I read a comments about IRC chats Webchats, there are twitter feeds, shoutbox, etc.
The wideband chat on https://eshail.batc.org.uk/wb/ gets used a lot by the DATV'ers
The freenode chat on the NB not seen much activity at all, unless it is all private chats between individuals?
I am not on facebook yet so can not comment about that, but notice there are a few QO-100 groups?
It looks like there are many, many ways of getting a message across to potential and current users, I really do not know which is the most popular to visit, but wonder if they all put forward the same message on power levels and spectral bandwidth/purity.
Adrian
You say the "pie tin" reduces side lobes at 2.4GHz would this mean reduced transmit outside the dish area, I am sandwiched on 3 sides by other houses rather close by, so the less 2.4GHz I throw towards the other houses the better. I am thinking forward to when I try DATV at higher power. I know I am just being cautious. What height is the ring and does it go on the outside of 105mm ie can it be fitted to an already made POTY.
