Category Archives: Antennas

QRPp on an IC-705

I have been wanting to work QRPp for while after reading about contacts CW ops were making on 80mW. The idea was to make a simple crystal controlled transmitter and use the 705 as the receiver. Than I read about the MFJ-813  which is advertised as a 5W QRP watt meter. Yesterday one arrived and has just been tested.

The 813 is reasonably accurate for such a low-cost meter. Starting with the 705 I set the power to 5W the meter showed 5W. Then I turned down the power to 5% and the 813 meter reading was remarkably close to 500mW. Turning down to 1% output on the 705 the meter read 100mW.

Next are some on air tests with 100mW – 1W power levels.

 

 

 

20m End fed half wave

I used a 20M EFHW and few years back with varying degrees of success. It was about the time when ‘squid poles’ became a popular antenna supports. The single core wire element was wrapped round the pole but the problem was that most poles then were made of a carbon fibre material which made them conductive. The antenna did not work so well.

This week I tried out a new, 10M fibreglass pole and, like before, wrapped the wire round to the pole. First indications are good with low SWR using a commercial 49:1 balun. This was much better than using the small EFHW tuner I made some years back.

Another idea is to use an off centre loading coil to make it a multiband antenna. More to come, watch this space.

 

New antenna analyser

I have been trying to setup the Buddistick outside but it’s been so bright I could not see the screens of the cheapo analysers I have. So, decided to upgrade to a more professional version, the Rig Expert AA-55 Zoom.  The first impressions are good.

Not used it outside yet, waiting for enough energy to do the job bit it does look better than the mini VNA,

Auto antenna tuner kit

There are many different versions of an automatic antenna tuner on ebay and other sites. Some come with a case while others are supplied as a PCB and a bag of parts. There are few instructions around but there are circuits diagrams, or schematics, on some sites.

The board as received

The insulated rear panel

I ordered what I thought was a complete PCB with case but what arrived was a populated board without a case. I complained that it was different to the photo for the item and accepted a partial refund which amounted  nearly what I paid. I then ordered the case for under £13 post-paid.

The board came with SMA sockets already attached which meant it would not fit in the case, so they were removed. Assembly was a bit fiddley, but all seemed to go well. The first power up showed the screen was working. Next came an RF test which did not work. Some quick tests showed that the rear panel had no earth connections to the PL259 sockets!

I decided to make a new panel from aluminium. After reassembling the case and testing with a TX connected to my long wire antenna  everything worked as it should.

I now have an fully automatic ATU that senses when there is a band change and retunes.

The new aluminium panel ready for testing

IC-705 and a new portable antenna

Although I still make stuff it is getting harder especially with small components. Last year I was told that I have rare form of cataracts. That makes working on circuits boards difficult. When the current pandemic is over maybe they will be able to replace to duff components and restore the circuit to its original condition.

This is all leading up the to be the excuse for buying an IC-705! It’s an exceptional radio with amazing performance which is hard to believe for an old timer brought up on HF receivers that occupied a full 19 inch rack.

 

Above left – Marconi HR11 telegraphy receivers with the boss pretending to tune one and above right, Plessey PVR800s telephony receivers. The first transistorised professional RX for the HF point-to-point service. Pics from around 1968 at PO radio station Bearley.

The IC-705 which I can hold in one hand!

So now the work is on perfecting the HF /P antenna. I have gone back to an end fed half wave made from a homebrew system that breaks down into 1m long sections. The aim is to cover 40m-10m with different lengths of wire wound on a reel, after removing the washing line. See Steve Nichols, G0KYA,  post on his blog here.

I also have a couple of light weight fibreglass poles and a drive over support just to make everything more flexible. That will allow me to operate from the car/micro camper.

 

 

Home construction, QRP, solar power 8 months on

When I came back to amateur radio in March 2018, I set myself some aims, more aspirations really.  I said that I wanted the station to be QRP, all homebrew and solar powered.

I have always enjoyed making stuff and now I have finally retired I have a lot of time to do just that. Second, I have previously thrown money at the hobby, got on the air and become bored.

QRP? Life is too short say the kilowatt cynics. Over the years I have enjoyed using a lot of small, home made radios with spectacular results. It takes more effort to winkle a signal out of the noise, but the rewards are bigger. Like many things in life it takes effort and patience to get results but the reward are higher.

uBITX

As the solar power I am trying to reduce my carbon footprint as I fear we are on the brink of a climate catastrophe.  You may not agree but I would urge you to read the evidence, from climate scientists, not newspaper articles, who agree that there is a big problem. Besides saving energy in the home saves money!

80w folding solar panels

So, 8 months on I am back on the air with a uBITX with the mods to reduce spurious emission and harmonics. Next is the AGC board. Using a LiPo battery I can get near 20W output but that is trimmed down to 5W. I also have a 20M QSX and am eagerly awaiting the launch of the multiband QSX.

20m QCX

The auto antenna tuner is nearly finished but in the mean time I have a 9:1 balun at the bottom of the antenna and an L match at the radio end. I can get below 1.5:1 from 106m to 10m which is fine for now.

The only thing to sort out now is a more permanent solar panel battery charging facility. I have the gear from ‘the van’ but want something more permanent.

80M DX on the uBITX

This is a recording of W1MBB on 3.798Mhz at 0754 this morning. My antenna is a long wire strung between two trees with a homemade tuner. I also heard a ZL this morning.

 

So, what does this prove? That the uBITX receiver works well although I must add the AGC board! That there is DX out there if you know where to look. That amateur radio need not cost a lot. And, most of all, there is nothing to beat the kick of building a radio and using it on the air.

I know I could never work him on the uBITX but I also know that using higher bands it is perfectly possible to work across the pond on 2W of CW.

Why home construction?

I am often asked why I bother with home construction. Why make stuff when it is so easy to go out and buy it? The questioners sometimes go as far as asking why I waste my time.

There are lots of reasons; it is something I have always done, it saves a lot of money, you know your gear well so can repair it and most of all I learn something, sometimes the hard way!

All of that is summed up in this quote I found today:

“The excitement of learning separates youth from old age. As long as you are learning you’re not old” Rosalyn Sussman

First test of the remote ATU. The control box is the next job.

I am now eight months in to my aim to build a totally homebrew station. I am at the point of having some working transceivers, power supplies, an antenna analyser and a long wire antenna. The remote tuner is almost done but is proving troublesome. By the end of the year it will all be sorted!

Slow scan TV from the ISS

At the third attempt I managed to copy an SSTV image from the ISS. It is noisy as it was orbit 1924 which showed a minimum distance of 1038km and maximum elevation of 19.15 degrees.

I used the dual band antenna I made last week with a Baofeng GT-3 and a Zoom H5 audio recorder. It all worked well enough but a bit more gain at 2m would have helped. I am thinking of making crossed yagis for both 2m and 70cms. As the wind chill was somewhere around -3C today the new antennas will be motor driven!