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Friday 26 July 2013

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

Saturday 13 July 2013

Software Defined Radio

I am adding Software Defined Radio to the shack, this is in the form of a Realtek RTL2382U based USB DVB receiver, equipped with a R820T tuner that can receive from 24MHz and up, the shack computer has been set up in order to be able to utilise the RTLSDR when it arrives.

The receiver in question is this device from  The device comes with a very short antenna that plugs onto the unit using an MCX connector so you will need an adaptor to the Belling-Lee connector, then if you want a reasonably better connection you can get an adaptor from Belling-Lee to F connector

As a stopgap you could use a pair of "rabbit ears", which you can get from Poundland in the UK (or whatever you have in your country that is similar), something I have actually done with the FM broadcast receiver in my living room's Hi-Fi system and it works well in Band II despite suffering some damage, though it should receive other frequencies but a better antenna and coaxial cable would be more beneficial when possible, especially an outdoor antenna as it would be less prone to interference.

The same coaxial cable used for satellite dish LNB feedline is also a good idea as that is low-loss.  There are instructions online on how to build antennas for use with these devices as well as suitable software for all platforms and the drivers to make the devices work, do not use the CD supplied with the device as this is the software for using it as a television device.

This is something I have been meaning to play with for a long time, now I have that opportunity to do so, stay tuned for more.

73 de 26CT730

Friday 28 June 2013

Scooter CB... the theory

I plan to purchase a 50cc scooter/moped in the not too distant future as I am starting to find bus fares are costly and am spending £15 a week and I'd spend less than that on riding a scooter a week, and I plan to fit it with a CB radio.  I have identified a few issues already that have to be overcome, these are:

  1. Lack of a suitable groundplane, without which a standard mobile antenna will not work, so an antenna designed to be fit to fibreglass vehicles would be needed, at least two have been identified as suitable though it is possible to buy an EGP kit, however I cannot buy this until I have the scooter.
  2. A suitable power source.  My understanding is that most modern scooters have a 12 volt electrical system, so simply fitting a cigarette lighter socket to it should be no problem, this will then accommodate the car adaptor supplied with current handheld CBs such as the Intek H-520 and Midland Alan 42 Multi (I have both radios and bought the latter specifically for this).  The supply would also be fused on the socket's positive line to avoid any fires or other such issues, and possibly ignition-switched
  3. Headset.  A standard CB radio cannot accept an Icom type headset connection (as found on PMR446), except on some very expensive radios that putting onto a scooter would not be wise to do and would not be removable as readily.  As all handhelds currently on the market are Icom headset compatible this makes them usable with motorcycle headsets which simply are fitted in the rider's helmet and have a PTT on the handlebar to allow transmission, handheld CBs do not have VOX either so this may be solved already but I need a motorcycle helmet first.
  4. Mounting the radio.  This will depend on the scooter, the handlebars themselves are a no-no for obvious reasons, it would need to be mounted so it can be accessed easily yet not interfere with my operation of the scooter, the planned mounting location may also dictate the location of the cigarette lighter though I may use the same socket to charge my mobile phone.
  5. Ease of removal.  I decided that the Intek H-520 Plus is quite a cumbersome radio for this task, as is the cheaper H-512 as it uses the same basic case, so instead I chose the Midland Alan 42 Multi. Also the car kit supplied with the Midland slides onto it in place of the battery box, the Intek radios use a small screw to hold it's car kit in place on the underneath of the radio and requires the user to remove one of the batteries before using it on a cigar lighter socket.
  6. Waterproofing.  The antenna connection can be waterproofed with self-amalgamating tape, in particular the connection at the antenna itself as this will be permanently connected, the radio itself however is something I will have to look at at install time.
  7. Security, as the radio is quick to remove this should be no problem, when I am not using the scooter I simply remove the radio and return it to the house.
I am not the first person to fit a CB radio to a scooter/moped, I know of at least one other that has done this, though they used a different radio, a Midland 38, I suspect this was for static mobile use rather than actually on the move given the radio used.

I will post an update once I have a scooter and put this theory into reality. I will also include photos of the installation.

73 de 26CT730

Saturday 22 June 2013

Another 446 gateway update

It has been a while since I've been able to get on air as the last few months have been VERY busy for a variety of reasons.

The PMR446 gateway computer failed again but I may have solved the problem.  The current 80GB hard disk was not being detected, I have, however, replaced the power supply, which was just out of a theory I had, and the hard disk was detected and the gateway computer booted successfully, the gateway is now operating on it's usual channel and CTCSS combination, it has also been up for a week without a fault, I am keeping a reasonably close eye on it though I'd need to keep a radio on me at all times to be absolutely sure and I would not be able to do so.

I am happy that the gateway is back on air, this means I can hopefully restart work on the CB gateway again, and hopefully that will be on air before the end of the year.

73 de 26CT730

Thursday 11 April 2013

446 gateway update

I have managed to get the PMR446 gateway back on air within the last 24 hours, using the 80GB WD hard disk, the original Maxtor hard disk has completely failed and has been removed from the machine awaiting tests to find out what happened to it and if it can be salvaged.

Reconnection of the autokey device to the computer was straight forward, it worked the first time, though there is an undesirable hum in the received audio it does not have a major effect and transmissions from the gateway are perfectly audible.  I may look into fitting a ground-loop isolator onto the gateway to see if that cures it but it isn’t a major issue at this time.

The gateway is operating on it’s usual channel and CTCSS, so feel free to use it if you are in Richmond, you may not get a reply immediately but be patient.


73 de 26CT730

Sunday 7 April 2013

PMR446 gateway failure

My PMR446 gateway has within the last month suffered a failure in either it’s hard disk controller or two seperate hard disks, this means it is currently off air and due to my fiancĂ©e visiting me this last month it has been awaiting repair as she has been priority.

I plan to install an offboard IDE controller in case the onboard one has indeed failed, should this not be the case I will be looking to source a new hard disk and possibly an SATA controller if I end up with an SATA hard disk in the machine.

My plan is to get the gateway working within the next week or two, and hopefully it will be back on air before the end of April.  I will also resume work with the CB antenna system to hopefully get the CB gateway on air properly in the not too distant future.

Hopefully all will be working again very soon


73 de 26CT730

Friday 18 January 2013

ShackCam update

Taking inspiration from a none-radio related project I am working on I have modified the ShackCam page so that instead of the inelegant auto-refresh of the page, only the ShackCam image will change, this resolves one issue in that the ShackCam page would need to be manually refreshed if the connection were to drop in it’s previous setup, a blank space will appear instead while the page script tries for the image until it can find it again, so there is no need for user intervention here.

The ShackCam is online nearly every time I am in the shack, you can find a link to the right of this page.


73 de 26CT730

Monday 7 January 2013

CB gateway testing update

The gateway went through it’s first proper test yesterday with the gateway computer in its new configuration.

Yesterday was the monthly DX net I take part in, as this was going to be high traffic I put the CB gateway into the DX net, and it did very well and did not bounce, this makes me pleased so I have for the moment left it switched on and put it back into the 446Muppets English net where it will spend nearly all of it’s operating hours when operational.

I am pleased with how well the CB gateway is now working and look forward to getting the antenna connected to the radio next.

As for the DX net, that was enjoyable, though I did make at least one contact that I hadn’t logged myself, I was listening for the most part to keep a close eye on the CB gateway, and got myself in the host operator’s log early on, the ShackCam was on during this event as well Smile

I shall post an update on the CB gateway’s progress soon


73 de 26CT730

Saturday 5 January 2013

Another CB gateway update–positive progress

The new matched RAM for the CB gateway computer arrived this afternoon, though I was a little concerned it may not, as I have since installed it and powered up the gateway radio, the gateway appears to be working rather well, so I am impressed with this, the lockups that were happening have since been largely eliminated with the replacement of the RAM and CPU.
The gateway is now being tested for any issues on it’s dummy load in the English net of 446Muppets, so far this is proving to be positive, meaning that tomorrow I can test it out in the DX net I will be taking part in
The antenna is to go given that I now have the dipole centre and I should be able to get the gateway on the air in February as I hope to do.

73 de 26CT730

Friday 4 January 2013

Another CB gateway update

But first a belated Happy New Year to regular readers of this blog, hope 2013 is a good one and perhaps I will hear you on air soon.

This morning the Moonraker dipole centre arrived ahead of the RAM for the gateway computer, though the RAM is on it’s way to be delivered either tomorrow or Monday, this leaves the two mobile whips to complete the antenna and then the tedious task of installing the antenna, though if I can have the gateway functional on just the dummy load currently connected to it on Sunday I can use my handheld CB to monitor it in the kitchen when I make refreshments during the day as I intend to take part in the DX net taking place that day though probably be operating in the shack as I do not fancy going out, the existing PMR446 gateway will not be used as part of this and will remain connected to it’s usual server.

I hopefully will be getting a car this year and naturally it will be fitted with a CB radio, my Midland Alan 78 Plus Multi B to be precise, if this gateway works I’ll be able to use it on the road, that would also work in favour of anyone passing through that is in range, though I don’t expect a good range to begin with due to the limited size of the antenna but we’ll see what happens when the gateway finally goes live.

I look forward to finally being able to switch on Richmond’s first and only CB gateway to the Free Radio Network.


73 de 26CT730