setting up receive for QO-100 at my QTH

The Es'hail-2 geostationary satellite, the first of its kind to carry an Amateur radio payload, designated QO-100, has been in orbit for some time now, and I listen to it now and again on the BATC WebSDR hosted at Goonhilly Earth Station in Cornwall and have got a rough idea of when it is active, I've had a look at how to receive it and it would appear it can be received with a Sky UK 60cm Minidish and LNB connected into the RTL-SDR, however the RTL-SDRs that can power accessories on the coax only can do so with 5v, a satellite LNB requires either 12v or 18v, the polarisation is selected using these two voltages, 12v for vertical, for the narrowband transponder, which I am interested in here, 18v for horizontal, this calls for a Bias-t which essentially supplies voltage to an accessory up the coax however at the same time prevents that voltage going into the receiver (or transceiver in some cases), a Bias-t simply has a capacitor to block voltage and an inductor to block RF).

LNBs generally have a LO of 9.75 GHz unless a tone is fed to them as well, which is not required for QO-100 as the 9.75 GHz LO is suitable, the downlink frequencies being around 10.4 GHz (though generally these LNBs specify a minimum frequency of 10.7 GHz), so on the RTL-SDR for me to receive the narrowband transponder requires me to take it's frequency of 10489MHz and deduct 9750MHz, this should be around 739MHz.

As I already have an LNB, which is designed for an oval shaped dish, the Sky UK Minidish, the biggest size they are in is 60cm for the north of the country is what I need, though there is a dish and LNB already on the building for my flat I cannot use this as it needs to stay set for the Astra 2 Satellites used for Sky UK and Freesat, so I need to buy another dish and this is what I had in mind as the LNB I have, a quad-output Visiblewave unit with Sky branding on the sticker, will fit this with no modification, this gives me an option to receive both transponders as the unit had a length of twin cable terminated in F male connectors, which I intend to splice and fit a Bias-T inline for each, powered at 12V and 18V respectively, however I'd need two RTL-SDRs of good quality, the NooElec NESDR SMArt is a perfect choice as it is more frequency stable than the standard stick, as reference I'll use the Goonhilly hosted WebSDR to ensure things are on frequency, LNB skew and dish alignment is obtainable from BATC.

There should be a YouTube video of my success (or failure) of receiving QO-100 with a Sky Minidish, nice to experiment with, if not I've got a portable satellite dish to take camping with me for television use.

73 de 2E0EIJ

RTL-SDR dedicated machine sort of set up

I have an old laptop with a display that has no working backlight, a Samsung RV510, and am putting this machine to use as a dedicated RTL-SDR receiver, it originally served as the now closed Richmond CB FRN gateway, with me having high SWR (and having to use a matcher), it remained closed for quite some time however the machine was in fact hibernating from the very point it was closed down.

It seems to run the SDR# software fine and works with both RTL-SDR sticks (I already know that the cheapo black one works, the NESDR SMArt was tested). so first test was with Soundmodem and APRS, it worked ok, though I don’t think I configured it correctly to pass packets from soundmodem to APRSIS32 so nothing was gated in that experiment.

Next was to decode DMR, it did not do well here either due to there being some noise on the frequency I could not seem to get rid of, though this was in the 70cm band and the supplied magmount is fitted with RG58, trying a piece of 213 and a dipole didn’t make a difference and destroyed my SMA-M to SO239 adaptor almost to the cost of the stick’s SMA-F connector (though the sheared pin was removed with Blu-Tack.

I am going to rehash my Handheld CB and PMR446 videos after either the Ripon or Blackpool rally, the first videos were all HT to HT (or in the 446 video between two units with fixed helical antennas) using this setup, the final location of this receiver of many talents will be next to my “Stranger Things” radio (the Realistic Pro-53 Patrolman, I call it that because it really looks like it was pulled from the Netflix series Stranger Things though I owned it before I heard of that).

The two videos will be done under the same conditions at the TX end, using the same radios (Intek MT-5050 for PMR446 and Midland Alan 42 Multi for 11-meters, both again using the stock rubber duck antennas), the RTL-SDR will be connected to an antenna using a lenght of RG213 to keep loss as low as possible, the antenna will most likely be in the window, outside if possible, and I want to make it from a couple of cheap CB antennas with the 3/8th thread on them as I have a dipole centre configured this way, that arrangement won’t be used for TX as there would be no choke.

The receiver works from as low as 24MHz right up to 1.7GHz. so 10-meters, 6-meters, 4 meters. 2-meters, 70cm and a lot of commercial, licence-free and aviation frequencies are also covered as well as the Amateur bands and CB frequencies, first things first is that I require a new SMA-M to SO239 adaptor and preferably a way to stop the SMA pin shearing off.

On closing I now have an extended battery to record video footage from the camcorder, this is so I can record footage of the Ripon and Blackpool rallies , Ripon is on Sunday (with an aim to have the video uploaded by Monday afternoon), Blackpool is two weeks later (with an aim to have the video uploaded by the following Monday afternoon)

73 de 2E0EIJ/26CT730

SDR mod complete (or kind of)

My RTL-SDR stick is now inside it's tin submerged in Aldi's own brand cooking oil (other discount supermarkets are available) and it seems to work fine and drift appears to be reduced greatly, there is one issue that occurred however.

The Neutrik USB connector and BNC connector are both coated with silicone sealant underneath, though it does not react with cooking oil the connectors aren't properly sealed and leak by a small amount when the lid is pressed on, not good, to remedy this I have decided to use Sugru, which may require me to temporarily remove the lid of the can to deal with, around the outside edges of the connectors.

The stick has little noise (due to a mod to the cable between the "A" side of the Neutrik and the stick itself, the shielding of the tin, and, of course, the cooling, it is currently placed on my bedroom windowsill and connected using a high quality Belkin USB cable.

Reception wise so far, as I am temporarily utilising the Nagoya NA-771 antenna, has been GB3IR, PMR446 channel 1 (which I was using for some tests to check drift and at the same time was in use by children as is normally the case), CB channel UK19 (me again for drift tests), the PPM correction ONLY had to be reduced.

This whole idea came from SDR for Mariners and the author seems to be bang on the money here, the stick can't get that hot if in oil, refrigeration may help further.

To make the most of the SDR I will naturally need a better antenna, the NA-771 is a 2/70 antenna, meaning it is only any good in VHF and UHF frequencies, and doesn't make a good scanner antenna, so that may need rectification.

In the mean time I think it's best to stress test the stick in its new enclosure.


73 de 26CT730

SDR enclosure almost ready for stage two

Posting this on my phone as the home QTH has no Internet connectivity since Friday morning, which has resulted in no PMR446 gateway in Richmond, unfortunately this is BT's issue as opposed to mine.

I found a second nut and machine screw today while tidying up, needless to say this allowed me to drill a second hole and fasten the USB port to the tin lid properly, I removed the SDR to drill the hole as I did not want to damage it, it was returned to the tin when the second screw was tightened.

The SDR is currently tuned to GB3IR, the local 2m repeater, the antenna is a 2/70 antenna so fine for this use, performance appears to be good, the next stage will be sealant around any holes to prevent leaks, then some vegetable oil for coolant as far as I dare fill the can, as per the information on SDR for Mariners, and a final bead of silicone sealant on the outside of the lid to be absolutely sure.

This has been a slow project but it is almost there, a scanner antenna will be next for this, hopefully I can see what this cheap SDR, when surrounded by metal and immersed in oil, can really do.

73 de 26CT730

PS, I hope to have Internet restored and the gateway operational soon

RTL-SDR enclosure prepped

I picked up 2 different diameter hole saws today to enable me to cut the hole needed in the lid of the tin for the USB connector for the SDR, the connector was fitted after a suitable hole cut and another hole drilled through for a screw (a second screw will be sourced and used later to finish the job).

A connecting lead for the antenna socket on the stick was sourced from the magnetic mount stick antenna that was supplied with the RTL-SDR stick, it was simply a small amount cut from the lead with the MCX connector intact, the cut off end was simply prepped and soldered to the appropriate points on the BNC connector, with the excess trimmed off, continuity was checked before the lead was connected to the stick.

The stick was then tested with just the antenna socket, I installed the SDR# software to do this, it worked as it should have done, the stick was then connected to the USB socket inside the tin lid and the tin closed up, it still works, the NA-771 antenna is not tuned for everything the RTL-SDR is capable of tuning to, but it seemed to work OK in the broadcast band, it of course worked fine in the 2-meter band and on PMR446 (PMR446 frequencies fall into the 70cm band in the US so to be expected). I tried it on 11-meters including on 27.555 MHz, but no luck, partly due to being indoors and partly due to being the wrong antenna for the band, a final test was to see if broadcast reception was eliminated while inside the tin, it was.

The last stage of this project is to fasten the USB connector down properly with one final screw, silicone seal the inside of the tin to be sure that no leaks can occur, fill it with oil after the silicone sealant has cured, and immerse the operating RTL-SDR into it, the reason I want it operating while I do this is to ensure that the stick continues to work while immersed in oil, SDR for mariners claims that it does.

It has taken me a bit of time but I finally have got the tin fitted out.


73 de 26CT730

President Grant 2 to be ordered soon maybe? (also a shack computer update)

I may place an order for a President Grant 2 next week if my finances look good, this will allow me to operate on SSB, in particular on my DXpedition to Tan Hill, however I will see what's what.

The reason I chose the President Grant 2 is several reasons, it is the first legal rig that allows you to switch between the new modes in the UK band (this is a recent update to the firmware in the radio), the radio is fitted with a power socket on the rear that the power lead plugs in to, this is similar to my Moonraker FA5000, a rig I hardly use now.

The President Grant 2 is easy to open up to export mode, inside there's a white wire and a jumper block, simply snip the wire and move the jumper, at the loss of your warranty and and your own risk, you also would lose the UK setting but you can get this back by moving the jumper back to it's original position.

It support's President's Liberty wireless microphone, a great idea that no one really thought of in the past, means you are not tied to sitting in the shack or your /p station, you can take a wander if you like, up to 100 meters I think it is, much like a DECT phone or a bluetooth headset.

Another nice feature of the rig is a choice of two backlight colours, orange and green, which also includes a dimmer so you're not blinding youself with a bright backlight at night.

There are other features as well on the rig but I'll do a full write up when I actually get hold of one, hopefully in a couple of weeks all being well

My shack computer has had a new motherboard, RAM, and CPU ordered for it, this would help with performance with regards to SDR use, there are incompatibility issues with the hard disk, optical drive, and existing graphics card, the hard drive has had an adaptor ordered for it to allow it to continue to work, the optical drive will be rectified later as it's not important at this time, the power supply should be sufficient for the new board, the only card that will be fitted is to be the CMI8738 sound card that the machine already has and that is compatible with the board.

Performance with SDR# has been dire with the RTL-SDR operating, the FRN client does work... just, the shackcam feed isn't really reliable on the machine (it's controlled by it both hardware and software, though I intend to replace this with a network camera,, which will make it software and link), and with plans to do the Amateur radio foundation exam as well I want the machine to reliably handle the Echolink software.  Another radio software installed on the machine is Zello, this runs reasonably OK but I tend not to use it as I use it on my phone more than I do on the computer.

Programming my Wouxun KG-UVD1P has proven unreliable with this machine, upgrading the internal hardware may be sufficient to remedy this (the official software, that is practically incomprehensible, works fine, the easier KG-UV commander doesn't read the radio properly, though it could be a bug with the software rather than the computer).

I should be taking delivery of the motherboard and it's ancillaries by Wednesday at the latest, for fitting that evening, which will take out the 446 gateway for a couple of hours but this is no real issue, the RAM on the existing board, if compatible, will be used in the 446 gateway computer to hopefully try and improve things, the GPU in that machine will also be swapped out with the one in the shack computer as I feel the one currently fitted to it is wasted in it and would be useful in another installation.

So, a better shack computer and maybe, just maybe, a President Grant 2 will be sitting on my shack desk soon, but we will see :)

73 de 26CT730

SDR improvement, an update

I have taken delivery of the two connectors needed to fit to the top of the lid of the metal container that will hold the RTL-SDR stick and the coolant (which will be vegetable oil), and have set up the USB port to be a type B on the outside of the case, in line with USB specifications and to allow the connector of the RTL-SDR to connect.

The next job I have to do is drill two holes in the lid, one to accommodate the USB connector (which turned out to be a little smaller than I initially thought) and the BNC connector, these will be sealed up with silicone sealant to stop oil escaping through the connectors, the RTL-SDR stick will then be placed inside the can, connected to USB and antenna first, then the can will be filled with oil as far as possible, the lid fitted, and the edges sealed up to prevent leaks.

As I plan to upgrade the motherboard in the machine to a more recent model the shack computer will be used, the board swap will mean a port change and reinstallation the drivers for the stick, this is not a problem for me, I have at least 3 compatible antennas for this new setup, or 4 depending on how you look at it, these are my Nagoya NA-771 2/70 antenna, 2 Intek KA-520 antennas (one is a bit bent but I think it works), and the stock antenna of the Midland 42 (I do not know the manufacturer's designation for it).

The RTL-SDR should run cooler after this and should not drift or require the offset to be changed, also reception without an antenna should be either heavily reduced or eliminated.

so, I can start to get this thing built and will try and order the parts to upgrade the shack computer this weekend, which I have already chosen.

73 de 26CT730

Planning a DXpedition to Tan Hill

I am planning a DXpedition to Tan Hill, home of the highest pub in England, my plan is to take a rig, battery rated around 10Ah, may get a bigger one (my scooter's battery is 7Ah and I need that to power my scooter's starter motor so I cannot use that), or a portable jump-starter with a 12 volt outlet, I just need a collapsible pole and antenna, I plan to make up what is called a T2LT for this purpose.  This is inspired by others going up hills to do this, and Tan Hill makes a good place, I'm sure the Amateurs would like it too, and best of all there's a pub up there for food and drink

Update: Listening to GB3IR, the 2m repeater in Richmond, this evening (I obviously cannot transmit as I don't hold an Amateur license yet) the Amateurs that were on air have mentioned Tan Hill so they actually have used it themselves for HF work, so I am not the first nor am I the last.

The pub itself stands at 1732ft ASL, so the location is pretty much perfect for radio, especially DXing on both 27MHz and 446MHz (I may give the latter a go as well depending on how much charge is in my radios, though I can charge them up prior to the event and take spare batteries, but my aim is to try on 27MHz, as it is sat around spare and it the better of the three mobile rigs I own I will use the Midland 78+ Multi B (the TTI TCB550 is on gateway duties so won't be removed and the Moonraker FA5000 has an awful s-meter and cannot do AM, as AM is now legal and my Midland 78 Plus is type approved for use in the EU as far as I can tell it is legal to use on AM here, for the full 4-watt output on AM, it is required to put the radio into the setting for Spanish channels as these use 26.965-27.405 AM and FM at 4 watts.

My new Sony headphones and my converter will also be going with me, just for those stations I may not hear easily, laptop, maybe, though a notepad would allow me to write down callsigns, I simply need to pick up a portable power supply (a battery and volt meter may be sufficient as a temporary measure until I can get something better), a telescopic or collapsible pole, and an antenna, preferably of the T2LT type.

I may also look into picking up a President Grant II CB radio, as I hear these are very good indeed, and I've wanted a President CB radio for a while now, but until then I will just use my Midland 78+ Multi B.

One thing that I intend to do is take an SWR meter, my good quality Zetagi combo SWR and power meter will be ideal for this role, my cheaper two aren't brilliant, one has a needle that is not as precise as it should be and the other sometimes likes to stick, one of these is connected to my home antenna system for the CB gateway as the radio is also connected to it and I need to monitor if the tuner is working as it should be on occasions.

on PMR446 the antenna will be screwed into the radio, so no meters, coax, or anything else.

If I take the computer I may take the RTL-SDR and use it with another antenna, provided I don't overload it with my own transmissions.

So, I'll post an update as and when this DXpedition takes place, Tan Hill is there, I might as well use it for radio.

73 de 26CT730

SDR improvement

After seeing an article on the RTL-SDR blog and a more detailed article on the SDR for Mariners blog I decided that to eliminate the excess heat (and by association the excess frequency drift) I would use a cooling method from this page, immerse stick in can of cooking oil.

This cooling method hast two plus-points

1. The liquid is not conductive and no damage to the stick should occur
2. The can will act as a faraday cage, the SDR alone contains no metal screen and picks up everything in it's surrounding environment easily without an antenna (I tried this with a CB radio connected to a home brew dummy load in close proximity with the gain at 0, it picked it up with little problem), in a metal enclosure it should not pick up anything

The can I have chosen is the largest golden syrup tin I could find, I have chose to modify this with two connectors, BNC for the antenna (this will be of the 50Ω impedance, rather than the 75Ω the dongle would expect but a mismatch shouldn't be an issue, to allow compatibility with scanner antennas), and a Neutrik NAUSB-W chassis mount USB port set up with the "B" side on the outside of the tin and the "A" side inside to connect the dongle to.

These will be sealed with silicone to stop the oil leaking out of the connectors and to keep air out.

I'll report back on how this works, apparently it works quite well according to what I have read.

73 de 26CT730

SDR in the shack

The RTLSDR device arrived this morning and I have it currently in the shack connected to the shack computer, when I have a bit more time I will play with it further, perhaps even on my Android phone as I hear with a USB OTG cable this is possible.

I shall let you know how I get on

73 de 26CT730