Remote magnetic loop antenna tuner

As you know, magnetic loop antennas require a tuning capacitor to tune across a range of frequencies,this is usually done manually by tuning the antenna with the capacitor, for maximum noise or strong signal and low SWR.

Manual tuning is not always ideal if the antenna is some distance away, a remote tuner is needed and this is usually two parts, a motor with a reduction gearbox and a remote control with electronics to control the motor.

I have found a suitable circuit that can do this and the majority of the parts and the motor can be obtained from the same place, there is a transistor in the circuit that has been discontinued so I have to find a suitable alternative, which I am working on now.

Obviously I have yet to buy a tuning capacitor to build my loop but I have an idea where I can obtain these and can test the controller before I connect the motor to a capacitor.

further research is needed but I should be able to begin construction by the end of the month.

73 de M6RSQ

Magnetic loop antennas–a follow up

As I have mentioned previously I have a desire to build a magnetic loop antenna for HF use, primarily with my CRT SS9900 on 10 metres, though something that could cover 12 through to 10 metres meaning will work on CB as well as I still have a keen interest in that side of things despite holding an amateur radio foundation licence and hoping to go for my intermediate exam very soon, as alluded to in my last post.

My antenna situation as you know is very poor right now, made worse due to the fact I live in a first-floor flat, though I have a CB antenna in the attic it functions very poorly with high SWR readings and the need of a tuner to prevent damage to rigs connected to it, though this antenna works on 10-meters as well the tuner does not and to get the SWR to safe levels requires it be tuned with both sides turned all the way up to 10 (the unit is a Euro-CB EM-110 and is really suited to 11 metres rather than 10 metres), 2 metres is currently done with an antenna on a biscuit tin, also poor but it does work.

This is where the magnetic loop comes in, and I saw a YouTube video showing a design made out of copper tubing, with a power meter on the larger loop itself, a variant of this design was also on YouTube by an English member of Charlie Tango (of which I am a member with the callsign 26CT730) for CB use, with the right capacitor and correct dimensions I should be able to build a loop to this design (without a power meter fitted to the loop itself as I intend to fit the loop with a remote tuning system utilising a stepper motor and gearbox) and be able to start using 10 metres, despite the poor conditions at this time on that band I am eager to give it a go, also as I have not played with 11 meters since I scrapped my old car this would be a good opportunity as I understand CB is alive and well and there are regular nets held now, even on the midblock using AM and SSB since those modes became available to UK CB operators in 2014, but naturally I am keen to give 10 metres a go, whether I get a working magloop before or after I get my intermediate remains to be seen however I intend to make sure I get on 10 metres regardless, I have invested in equipment for that band I may as well use it.

I know I can get copper and plastic tube locally but for a suitable tuning capacitor I may have to look to rallies to do so, the requirements are that the tuning capacitor will work happily up to 4kV (though I suspect 50 watts is far below this but I like the idea of a safety margin).

The antenna will be connected with a suitable SWR meter in line almost permanently, my Zetagi Mod. 203W is perfect for this as it covers a frequency range of 26-30MHz for TX power measurement and 3-200MHz for SWR measurement.

I will post more on this subject as it progresses

 

73 de M6RSQ

Upcoming rallies–planning

As you know since I was licenced in 2015 I have attended whatever rallies I could, notably these have been the Blackpool rally at the Norbreck Castle Hotel and the National Hamfest, though in December I was also at the Bishop Auckland rally in Spennymoor, this year that is to be improved on and plans are already underway.

It comes as no surprise that the first rally I will be at this year is indeed Blackpool on the 9th April again at the Norbreck Castle Hotel, only a couple of weeks later I plan to be in attendance at the Ripon rally as I missed it the last two years, of course I will also be at the National Hamfest again this year, as well as the Bishop Auckland rally in December.

one of my main aims is to get hold of a suitable tuning capacitor for building a magnetic loop, for this I will take my multimeter with me as that can measure capacitance, if I can also find some other materials suited to building a magloop that will be even better as I am very keen to get on 10-meters (and HF in general) and if I can source the parts at rallies that will be excellent, of course I need to know how much power I can get away at putting through a tuning capacitor, so I shall ask of course.

Hopefully I can complete my aim at either Blackpool or Ripon.

 

I’ll post an update once I have attended the first rally, of course that is Blackpool.

 

On closing I hope to take my intermediate exam soon, wish me luck

 

73 de M6RSQ

APRS map display on tablet

I found that it is possible to connect a tablet to the Yaesu FTM-400 to display the data on a map (in a similar manner to aprs.fi), this only uses the data cable that the radio is supplied with and a USB-OTG adaptor.

APRSDroid isn't reported to work with this in this manner, so a different app and approach is needed, after a little bit of searching on Google (other search engines are available) I found a suitable app that reportedly works with the FTM-400, and needed only two setting changed, both in "DATA" in the main menu.

Before venturing down to the car to test this out I tested my tablet (a Huawei MediaPad T1, the 4G and WiFi model supplied by EE) with the USB-OTG adaptor I had spare and the data cable supplied with the FTM-400XDE, the tablet operated as it should have, I then went to the car to connect the radio and tablet together and it worked again as it should have, each station received by the radio was displayed on the tablet, and if it contained location data it would also appear on a map, exactly as intended.

Now I know this works I have to solve a second problem, running the tablet like this with the USB-OTG adaptor plugged in means it cannot be charged, I need to find a way to allow the tablet to charge and at the same time run the interface between radio and tablet to display the APRS data on a map, at the moment my efforts to figure this out have come to nothing, replacing my car's stock head unit with one that runs Android is a possibility but these are usually double-din and are expensive so I have ruled this out, modifying an OTG cable may also be possible but I have not found any schematics that do this, safely or otherwise, of course I shall investigate this

My third problem is a mount for the tablet so it won't get in the way of anything while the car is under normal operating conditions, though for obvious reasons I'd not look at this while driving, of course I have to figure this out owing to the car's lack of useful space and where the data cable will need to run, this is now a work in progress,

Now I have it working I'll see how it pans out

73 de M6RSQ

Bicycle mobile... perhaps?

Recently a friend of mine suggested I should go on a bike ride with them, presumably when the weather is better, in their local area, I've already looked at a cycle carrier for my car (only one exists that will fit it) and worked out everything that this entails, this gave me another thought, bicycle mobile operation.

My bicycle is fitted with a luggage carrier and pannier bag (both from Halfords unsurprisingly), the carrier is metal so a magnetic mount antenna could in theory be used on it, however I've not tested this in practice.

I also require some kind of electrical arrangement to run a radio, to keep the size down and make operation more convenient with a suitable headset I am looking at solely HTs for this, and many of these come with car adaptors or have them available as an aftermarket accessory, this then requires a cigar lighter type socket (available online or from, you guessed it, Halfords, though Maplin Electronics sell these too in some of their stores that I have seen lately), and a 12-volt battery (or two 6-volt batteries), with the circuit protected by a fuse naturally.

As I have two CB HTs that I know to work, I can use these for any licence-free purposes over a reasonable distance (PMR446 is also an option but none of the radios for that band have car kits except for one designed for in-car use which would prove impractical as it is not an HT), I already have the Midland 42 Multi, the car kit modified somewhat for the abandoned scooter CB project that for various reasons did not happen (I say modified, just waterproofed with Sugru), my Intek H520 Plus can also be used in this manner though the Midland is smaller overall with it's car kit attached, both radios still work on both bands, though if I am out cycling with others and they use a similar setup then we'd agree on a channel before departing,

I still have the top box from my scooter (as I still have the scooter itself), I was thinking to use this to mount the batteries and the antenna to as it's a cheap top box and it locks, I would need to work out how to fix this to my bicycle's luggage rack with the antenna as far back from my head as possible and make it possible to remove for stowing on the bicycle rack on the car when transporting it.

Running coax and power along the frame should be relatively straightforward, cable tied to the frame out of the way of the brake and gear lines, thus allowing the brakes and gears to function, but then comes the issue of mounting a PTT and the radio itself.

On the front of my bicycle there is a light bracket manufactured by Bicygnals for their wireless turn signals, the front unit of the pair takes up most of the width of the handlebars leaving little room for anything else aside from the bell (the gears are grip-shift), fitting a radio and a PTT could be a tall order however I intend to look at the bike with the lights fitted (as they are indicators they are fitted at every ride, the rear set don't pose too much of a problem from what I can tell as they are a smaller set and therefore I'd still be able to get away with the top box battery box solution.

Although I primarily want to use the setup for CB/11 metres I may use it for 2-metres as well but should realistically be able to get away with using a longer antenna on the HT

I'll let you know how I get on with it in the near future.

73 de 26CT730/M6RSQ

2017 in radio... what is to come to for me all being well

Well it is now 2017, and of course radio will continue to be a hobby I enjoy, so what is to come for me.

Well rallies first, my intent is to attend the Ripon, Blackpool and Bishop Auckland rallies as well as the National Hamfest, and any other rallies I can get to, my attendance at rallies has been poor so far but I've made the National Hamfest twice.

On-air activities, probably won't be too much happening during these winter months, I can use this time to do any antenna building and sorting out of the 'shack' as soon as possible, even getting the ShackCam built as it is still not finished yet, during the spring and summer I'll probably play with 2-metres and 10-metres on a hill, maybe go back to my roots and do a bit of 11-metres on a hilltop as well, I plan to buy a drive-on mast stand for this and maybe operate from Tan Hill as it is an excellent spot from a radio standpoint, I will still be active mobile on 2-metres both analogue and C4FM where possible, I will be doing more with System Fusion and APRS as well.

I intend to keep training towards my intermediate licence, and all being well gain my full as well which will be excellent if I can get through both this year, but if not I will be fine with my intermediate, may require me to get a new battery for my car to accommodate the rig but I will see in time what happens.

Also as alluded to above I intend to do some satellite operating using a home-made antenna for the job, and I look forward to making a satellite QSO this year.

That should be it I think but there is a chance I'll think of something else after pressing the button

73 de M6RSQ

Amateur satellite

After watching a segment of episode 12 of TX Factor about operating through satellites I thought I would give this a go myself as all I need to do this is a suitable dual-band HT, as all mine are Chinese one would think they wouldn't be suited, as they can do what the offerings from the big names can do then they are fine for the purpose.

The satellite I am interested in, and as noted on the TX Factor episode referred to above, is SO-50, as it has an FM transponder, with uplink on 2-metres and downlink on 70cm, as it would be massively impractical to use the -600kHz split on a satellite due to the size of the cavity filters used at 2-meter repeater sites that achieve this so the signal goes up on 2-metres and comes back down on 70cm, but it isn't that straightforward as the Doppler effect has to be compensated for, programming the HT with the frequencies for the satellite beforehand will save you trouble here, the frequencies for SO-50 and other Amateur satellites are available on the Internet.

Knowing when the satellite is to pass is another thing you need to know, I have already gone ahead and downloaded two pieces of software for this purpose, on my Android phone I have AmsatDroid Free, and for my laptop I have Orbitron, the latter software being mentioned in the same TX Factor episode noted above, and this runs fine on Windows 10, so now I know where SO-50 is at any given time the next bit requires I be able to transmit from my HT through the satellite and my HT's rubber duck antenna simply will not do, for this a Yagi is the best antenna to use, but it needs to be of a design that will work on both bands, the most popular antenna appears to be the "Arrow" antenna, the original of which is actually made from arrows for the antenna elements, and because we're doing cross-band operation we also need a diplexer (this is correct, it is not "duplexer"), which from what I can tell is simply two passband filters, one high-pass for 70cm and one low-pass for 2-metres.

The Arrow antennas are not cheap, so in the spirit of Amateur radio it makes perfect sense to build one using bits from the junk box, and from a DIY store (B & Q in my case as it is the closest one to the home QTH), and I like to build rather than buy antennas where I can to save money, and considering that one may simply use their arm to move the antenna with the satellite it needs to be lightweight, wood for the boom would work well here, but if you do use wood it should be varnished to protect it should you be out on that hilltop and the heavens open, waterproofing the coax connections is also advised.

Once you have all the information regarding your chosen satellite, an antenna, a programmed HT, go out and make some contacts, but be aware that satellite QSOs through SO-50 are similar to contesting, usually callsign, location (locator square) and signal reports as the satellite passes for a short duration and is often very busy, listening before keying up is well advised, as is the use of headphones so you can hear the satellite better, also run the radio with an open squelch.

As a foundation license holder I am restricted to 10 watts, as is anyone with a foundation licence, antenna gain may push your actual radiated power beyond this level so dropping the radio to a lower power setting may keep the foundation licencee within their power limits and still legally use the satellite, gain and other such factors are beyond the scope of this blog, and from what I understand SO-50 doesn't need more than 10 watts anyway into it and by the time the signal gets there it probably falls well below that.

Having a second person on hand to assist with the operation may also be a good thing, as they are not transmitting they do not need to be licensed, adding a second pair of headphones for the assistant to help with logging may be a good thing too, the assistant can also help position the antenna leaving you free to carry out the QSOs.

And finally, building the antenna simply requires a search on Google as there is a lot of information on the subject and many designs are available, and you could further this and build the diplexer as commercial ones are about £30+ depending on where you go, and you get the pleasure of building the entire thing yourself if you do, and save money.

I look forward to working some stations through a satellite very soon, just got to get the festive season out of the way first.

73 de M6RSQ