Posts by 2E0ILY

For completeness and to say a most sincere thank you to those who responded, I'd like to report the LTE filter has cleared up the interference totally without moving the dish or anything else, so I can resume my TX side build with some confidence. Thanks again everyone!

Please await replies from much more knowledgeable members, but speaking in general RF tems I think what I would do is put a current meter in the supply to any pre amp before the PA and see if TX'ing shows more current draw from the first device after the Pluto. If so, how much change from resting to TX'ing? As you know I am watching your progress with great interest as we are treading similar paths Good luck.

I need to get myself one of those mini VNA's as i do not have anything to check antennas or coax at these sorts of frequencies, I am Googling your power meter in a minute! I have worked mainly LF (137khz) and HF previously, these UHF frequencies are new to me.

I have had this dish and mount for well over 20 years, I think it's of Swedish origin. I did have the paperwork, but it has been lost I believe. I am curious if anyone recognizes it, the mount is extremely well made with phosphor bronze and probably Teflon bushings, and the galvanizing is only now beginning to deteriorate, despite spending 18 years on damp ground outside! I ask because if the makers are still in business I'd be interested in seeing their current products. Thanks.

Quote from DC7KG

What is the distance of the interference lines?

I am not sure, I will have to connect the Pluto up again tomorrow, zoom in to a few lines and try and get the frequency spacing, I'll have to wait until then as I need the laptop for some work tonight, I'll let you know, thanks Detlev.

Quote from DC7KG

Hi,

I suggest to add an attenuator. That is the simplest method to see if something changes.

Detlev

I should have said, I have tried an attenuator, in fact several from 3 to 30dB. All signals get weaker, but relatively the interference to wanted signal ratio is unchanged. Thanks for the idea, and sorry for forgetting to mention this.

Quote from dm4im

Hi there.

Why should a filter do the trick for the pluto when the screen looks clean without a filter when using a sdr-dongle? I believe there's something wrong with the pluto or the PC. Maybe the USB-power is dirty or too weak.

73, Martin

I am assuming the Pluto has a very wide bandwidth front end and if it sees strong out of band signals to those tuned the software will display them? Perhaps the RTL dongle can't see these signals? I just tested the Pluto using a battery USB supply on the power port of the Pluto, instead of a second USB port on the laptop, or a USB powered hub, and the results are just the same. So I have to assume the signal is coming down the antenna coax, and not via the power source for the Pluto. That of course leaves the possibility of the Pluto being faulty, but it works fine on my 2 meter VHF Yagi and 2 meter vertical antennas, so I am still hopeful a filter will do something. Thanks Martin.

Quote from DC7KG

Hello,

which size is your dish? I use a 60 cm dish without any problems. A 10 dB attenuator or 740 MHz filter has no influence.

Detlev

Hello Detlev, my dish is quite big at 1.8 meter. It has a combined POTY / Bulls Eye LNB on it ready for TX at some stage. Do you not think a LPF or BPF will help? Thanks for the reply.

Quote from dl6dca

Hello Chris,

test it with bandpass for 739MHz or LTE Blocking-Filter. Look https://www.darc.de/fileadmin/…ung_QO100_Bericht_1.1.pdf

vy73 Wilhelm

OK, I have a spectrum analyser but I don't know if it has the range (I suspect it does..) and I am not very good with it, I am always afraid of blowing the front end! It's an HP8568B so pretty decent. I have the tracking generator for it, too I will look into making one, but meanwhile I have ordered a commercial one off Ebay just like the one in the .pdf you kindly linked to. Many thanks to you Wilhelm, have a good weekend and look after yourself!

I have been listening to SSB with an RTL dongle and SDR Console, and had excellent results. I swapped to my brand new Pluto SDR and see a lot of regularly spaced lines of interference on the waterfall. This is on the same USB port of the same laptop, and the same dish and Bulls Eye LNB. Disconnecting the LNB causes the interference to disappear. Running the LNB bias T from a battery does not get rid of the interference.

Has anyone any ideas as to what the cause may be please? Thanks

Thanks for sharing the chip type, that's useful info.

If I want to bring the forward and reflected voltage signals out of the case of my on order AMP2400v3 do I need to use feed through capacitors, and if so, what value might anyone suggest please? For cooling would a big computer CPU cooler with a small 12V fan be up to the job? The cooler heatsink's footprint is similar to that of the amp's case. Thanks.

I want to remove or isolate the stock TCXO and lock my Revision B Pluto to an external GPS disciplined oscillator. Ideally the GPSDO would also lock the LNB, so 25 MHz and a splitter sound cost effective.

My questions are, is a Pluto happy with a square wave input? I believe the LNB would want a sine wave, or at least a good LPF on a square wave signal?

What are the advantages and disadvantages of say a 10MHz, a 25MHz, a "stock" 40MHz or maybe a higher than stock frequency for the Pluto? Is choosing a Pluto lock frequency a matter I need concern myself with please? My thanks for any replies. Chris, 2E0ILY.

Thanks to Martin and Colin, that sounds straightforward and cheap, I appreciate the replies, thanks to you both. 2E0ILY Chris.

Thanks again Martin. I turned up an Acetal adaptor boss to mount the POTY 22mm tube concentrically in the plate today, and am awaiting the LNB to arrive. I will start with extending the tripod legs to bring the aperture of the 22mm tube to the same distance from the centre of the dish as the standard LNB and annular rings.

The POTY instructions say to not use the supplied plastic "lens" if fitting it to a prime focus dish like mine, and to leave the tube open. I am concerned about water and insects going down the open end of the 22mm copper tube into the LNB. Can I cap it in any way that doesn't do "bad things"? The more I get into all this the more it becomes apparent that my microwave knowledge is very lacking!

Another question has come to mind I am afraid. If I use the tripod plate as in the photo I hope to attach, it is of 170 mm OD, made of steel. My POTY will sit in front of it and I will turn an Acetal plastic adapter to sit in the plate in place of the annular rings LNB feed and the current old LNB, with the 22mm copper tube going through the plastic ring to a new LNB behind the steel plate. With the steel tripod plate being a larger diameter than the POTY reflector, do I need to have it a certain distance behind the reflector plate to stop unwanted interaction please?

I believe the 22 mm copper tube forms a wave guide to the LNB, is its length important?

For a no sweat, reliable uplink with a 1.2 meter prime focus dish, and probably a POTY TX antenna, although I may try a home made helical for the hell of it,, how much power do I need from a PA please? I am in the midlands, UK. I don't want to be buying 2 amps, I am starting dipping my toe in narrow band SSB, but my goal is wide band TV, so I would rather buy one amp that can be run throttled for SSB. Many thanks.

Thank you Lucio, I have now read the link and ordered a genuine TP-Link one with a supported chipset. from a genuine dealer, so should have covered all bases I can All the best and look after yourself.

Looking to buy a known good, branded USB to LAN adaptor for my hopefully soon to arrive Pluto. I have heard talk of powered ones, rather than taking their supply from the USB port, but can't see any like that. Is this important? OS is Windows 7, if that matters? I assume a USB3 adaptor is backwards compatible with the Pluto USB2 port? I also assume you can use a connector adaptor for the Pluto mini USB port to a C type adaptor connector? I think an actual known usable one is safer than me "winging it" Thanks for any replies, I am in the UK.

Thank you very much indeed for the reply Martin, it was most helpful and has given me a starting point to make a mount, much appreciated and all the best to you.

I am bringing an old 1.8 metre prime focus spun aluminium alloy dish out of storage and want to use it to access the QO-100 satellite. Initially for RX and TX of SSB stuff here in the Midlands UK. But I want to future proof the whole installation with a view to adding wide band ATV as an option. I may have quite a few questions I'm afraid, , but already joining this forum has been a huge help. I intend to initially buy a Pluto SDR, and have it in a weatherproof box by the dish, with it's own power supplies and feed the Windows 7 64 bit dedicated PC in the shack via a hard wired LAN. Is there any potential issue with doing this to reduce co-ax feeder lengths? For TX I am thinking of one of the Bulgarian 20W amps with a pre amp between it and the Pluto with a Bias T Am I right in thinking that I can pay a premium for an LNB already configured for a GPS locked reference signal?

Now this was a quality dish in its day , but it's now old... The LNB was used for general satellite stuff some years ago at my old house. I am initially looking for thoughts and recommendations for which LNB to buy that's currently available. Ideally I would like to lock the LNB to GPS. I have Trimble Thunderbolt but it's 10MHz. I also have a Ublox NEO-M8T-0-10 GPS unit which will output user defined frequencies, GPS locked.

I am not averse to buying a Leo Bodnar GPS however. I also want to mount the POTY antenna for TX on the same dish, at the same time. Rather than try and explain the current LNB mounting verbally I felt it much better to upload a zip file of some photos to my server for viewing. I have a small machine shop as I am in the motor race game, so I could make some simple constructions for mounting the new LNB / POTY.

Looking forward to any advice as I want to put the 4 inch tube in for the dish and get it mounted before the wife changes her mind As I said, I am in the UK as regards buying an LNB. Thanks for reading and for any replies. 2E0ILY

The photos are at http://www.chriswilson.tv/satellite/satellite.zip