Field strength meter

A field strength meter is a useful tool to have in the shack as it detects the presence of RF, and in the shack that is undesirable and can be a sign of potential feeder radiation, which as is known is often a problem if a balanced antenna is connected to an unbalanced feedline without some kind of balun, RF in the shack can also occur if the antenna is also in the shack (which in my case is more or less unavoidable at present).

A basic field strength meter does not require a battery, it works similar to a crystal set but without the tuned circuit, I had an old unreliable SWR meter for CB and set about salvaging components from it, 2 of these components were germanium diodes (silicon diodes won't work as well if at all), so I found what components I could close to the values specified from a particular circuit (some of these were from the SWR meter I had disassembled) and assembled a crude field strength meter onto a veroboard, in close range of an HT at full power it swings the needle on the meter display fully over to the end stop, a potentiometer reduces sensitivity so I was able to bring the needle back over to the end of the "FS" markings (this SWR meter had readings for field strength but they were not used in the meter as it was a basic CB SWR meter and the majority of CB users usually don't need to know more than if their antenna is working and not going to kill their radio's finals).

I built the meter as a proof of concept and just to practice my soldering skills, as I've not soldered anything in a little while and am a little out of practice, I plan to build a proper one, in a metal box, using exact value components for the circuit, at some point in the future, I could have built one of these for my Intermediate but my instructor had other things he wanted me to do and it didn't really occur to me at the time.

73 de M6RSQ

National Hamfest–Planning

As you are no no doubt aware, I have visited the National Hamfest every year without fail since being licenced, this usually takes place at the end of September, and I got the dates this far in advance from the latest RadCom.

My plan for this year is to stop overnight so I can be there both days for a change, I have already got the form to arrange this and this just leaves me to take holiday from work on the Thursday and Friday of that week.

I downloaded a form from the website but obviously need to print this to fill it in, then I can mail this to the Hamfest organisers in good time along with sending payment to them.

As I intend to stop overnight I intend to do some radio activities on site as well, this is where my recently purchased drive-on mast stand will come into it’s own, as I will be able to put up antennas for 2-metres and 70cm at the very least, I probably won’t do any 10-meter operation unless I can get hold of or build a portable antenna for that band in the interim.

Another issue I will have is powering rigs, the FTM-400XDE requires the car be running in order to run it at full power (which as I’ll have a 2E0 by then I should be able to do), though I’d be sat in the car when operating this radio anyway from the magmount on the roof (and I should be able to hit the Lincoln repeater from the Newark showground no problem), for analogue 2-metre operation I can use one of my HTs, as the 10-metre rig is also quite power hungry with the power turned up I would normally run this off my jump starter but I may not have a means to power the jump starter when it needs to be charged again, so I am looking into the possibility of obtaining a generator if possible as the Hamfest doesn’t allow the use of the site’s electricity hookups.

So, I have a lot to plan and 5 months to plan it in, time to get to work.

 

73 de M6RSQ

Blackpool rally 2017 - post rally

Having again attended the Blackpool rally I can safely say I did succeed in obtaining a variable capacitor that may work for a magnetic loop at high power levels, I also purchased a new rig for the home shack that replaces the Leixen VV898, a drive-on mast stand from SOTAbeams. and a Nokia extension speaker for the car, which works well with the FTM-400XDE, at least in analogue mode, hope to try this in Fusion mode soon as I've relied solely on the internal speaker, as the connector is stereo and the speaker plug is mono I had to use the supplied stereo to mono converter with the radio, the speaker is not fixed in final position just yet.

The drive over the previous day was good, the drive over on the return journey was not so good as I got held up in traffic on the M55, I spent most of this monitoring S20 though it seemed quiet for the most part,

The new radio, the QYT KT8900D, works well with my current 2/70 antenna and appears to have better rejection than the Leixen does.the QYT mic has bigger buttons on it and DTMF can be sent with the PTT pressed again unlike the Leixen, allowing access to Echolink and IRLP on repeaters, though for me at my home QTH this is just GB3IR, HG is seemingly having a repeater keeper change and from what I am aware currenlty lacks an NoV and has no linking anyway, and CD is screened by the buildings behind me.

I of course need to try out the radio further, assemble the mast stand and have a look at the capacitor properly before soldering it to a mag loop.

And my replacement radio also allows higher power, it's currently in low (10w) mode, the radio is 25w, great for my intermediate pass in the near future all being well and getting my intermediate licence.

73 de M6RSQ

Preparation for the Blackpool rally

With a week to go preparations for attending the Blackpool rally are now well underway, today I have programmed the frequencies for both GB3FC (which like the Blackpool rally is at the Norbreck Castle Hotel), and GB3OA, located at Southport, a short way down the coast, the former is a 70cm repeater, and therefore seems only to cover Blackpool sufficently for HTs, the latter is on 2-metres, the coverage map shows good coverage into Blackpool, this will be ideal as this year I intend to go on the day before to avoid an early start and be at the rally in good time to get parked.

I have also bought some stick on letters and numbers from Halfords and now my car has my current callsign on it, as I run APRS this will allow any other Amateur operator to know it’s me, also I don’t make a secret of being a licenced Amateur radio operator for the most part, however this will be the first Blackpool rally I have attended in which my car is equipped with APRS

This leaves a few final jobs to do, first of which is to have the oil level of my car checked, as at the home QTH I have to park my car on a slight incline I will enlist the help of Halfords, the next job will be charging of the jump starter in case the battery is flat at any time, and finally if I have the chance it will be to wash the car.

I also need a battery box for the capacitor tester I acquired and since modified to run off a PP3 battery, these are cheap and available from Maplin, and I will need a capacitor tester for testing of any variable capacitors I can find, both the tester and my multimeter will be called on for this task.

This week will go quickly, and on closing I hope the sun is out again going over to Blackpool.

 

73 de M6RSQ

thoughts turn again to the magnetic loop antenna

With the Blackpool rally now 2 weeks away, my attention has again turned to the magnetic loop antenna I plan to build for 10-12 metres (though 12-metres may not be immediately possible due to lack of equipment for that band), sizes, capacitor values, even the feedline from the antenna to the radio is now being worked out.

The capacitor can probably be sourced from the Blackpool rally, the copper tube to make the main loop is available from Wickes as it is the cheapest I have seen it, Homebase don't sell it for some unknown reason and B&Q sell it for more than Wickes, I hope to get the tubing this Saturday for both the loop itself (copper) and the support (plastic), the coupling loop can be made out of RG58 or some other coax with the braid and centre shorted together, or the same copper tube as the main loop.

The design I had seen by Larry WD0AKX also incorporated a meter, though I plan my final build based on this design it will have an enclosure over the capacitor which will contain a motor on a gearbox to tune the loop with the capacitor and I will keep an SWR meter on the feeder, for initial tests though tuning will be done with the capacitor and a plastic tool to avoid stray capacitance from my hands, my final build will also be suited to 50 watts (maximum on the Intermediate) if I find a capacitor that can handle the resulting voltage but until I get my intermediate I would only transmit at up to 10 watts, for CB use I'd always be at 4 watts or 12 watts PEP for SSB on the midblock.

Naturally I also want both my CB and my 10-metre rig to both be connected so I don't have to go behind them to swap the coax over, this requires a switch, preferably one capable of dropping the output of the "disconnected" radio into a dummy load and the "connected" radio onto the antenna, such a switch does exist, my good dummy load is, however, rated only to 50 watts, though this would protect the finals of both radios, though the SS9900 does have a HI-SWR function that prevents TX if SWR exceeds a preset limit however I prefer the reassurance of a load always being there, as repair of the finals is something I have no time to do, this idea makes sense as the President Grant II does not have a high SWR safety cut out, much like many off the shelf CB radios.

Hopefully I can start gathering what I need to build the magnetic loop antenna this week save for the capacitor which I hope to get from Blackpool or Ripon if it comes to it.


73 de M6RSQ

Rescue Mission

As you may or may not be aware, I have a temporary mast setup consisting of a fibreglass mast, a TV antenna pole, and a 25kg cement parasol base, which at present is not set up with any antennas on it.
For a time, the parasol base, as it is heavy, and the near 2 metre antenna pole have both lived in a shed that is incorporated into the building for the storage of conventional dustbins, this arrangement suited me well until I received a letter from the district council along with a black and white photograph of the contents of both sheds, demanding the tenants in this block cease storage in these sheds and remove anything they have stored within by the 31st of this month, after that date the council would dispose of anything still left in these sheds and fit locks to prevent further use in this manner, I had to act and today I finally rescued my temporary mast base, both parts, from the council’s mercy.
With the pole and base both now safely within my flat, I am at a loss as to where to store these, so in the mean time I’ll look to put them under the bed until such times I can do something about storage outside again.
The securing of these sheds gave me an idea however, if they are to be permanently locked, with no bins stored in them as wheely bins are too big to store here, I could mount a plantpot mast containing a magnetic loop at the top and get on the air from home at last on 10-12 meters, even CB/11-metres, which I have not played with since I took my old car to Tan Hill.
Something good may come out of something bad.

73 de M6RSQ

ShackCam update

The shackcam is currently still down as I have yet to complete the hardware, however the Raspberry Pi Zero which I intend to use now has an update allowing me to make it easier to set up, it recently had WiFi added to it meaning one less device.

Externally the camera, when finished, will still appear the same, and should still function as intended, it just means now that all I need to complete the job is one power cable, one Pi Zero, the current version of the camera and the adaptor cable to connect the camera to the Pi Zero.

This comes as very welcome news because it means not only don't I need a WiFi dongle but I also do not need a USB-OTG lead, two purchases I no longer need to make.

Hopefully I will have this built after my planned 10-12m magloop.

73 de M6RSQ