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This afternoon I went for a stroll up Ling Fell, LDW-205. It was a fine afternoon and I wanted a bit of exercise. I took the VX-8GR so I could test the new QRU feature of Lynn KJ4ERJ’s APRSISCE/32 software that allows an APRS user to receive information about nearby objects on request. I have created a QRU server for Wainwright summits so that an APRS user in the fells could receive information about the nearest summits, to aid identification or navigation.

I put a 2m helical antenna on the rucksack support for the walk up, so the VX-8GR could send my position. The other channel was monitoring 145.500MHz (S20) the FM calling channel. As I gained height I started to hear some loud bursts of interference, a combination of a whine and a buzz, on S20. When I got to the top I switched antennas to the RH-770 dual band telescopic. My first call was answered by Colin, 2E0XSD. His signal was moving the meter on the VX-8GR to an S3 or 4 but there was intermittently a lot of crackly interference over his audio. I tried engaging the RX Attenuator option in the VX-8GR menu and it did seem to improve things a bit, but not completely.

A bit later, when I was testing the QRU server, I could hear the APRS packets coming back from my gateway (which is line of sight from Ling Fell, just behind me in the distance in the picture) but they sounded distorted and the VX-8GR didn’t decode them.

I wondered if there was a fault with the cable to the rucksack mount so I put the antenna directly on the radio. My next call was answered by Geoff G4WHA from his car in the car park in Penrith. He was 5 by 1 but his signal was cutting out intermittently. I got the feeling the problem wasn’t Geoff’s, but was my receiver cutting out due to overload from some nearby transmitter. There is a commercial mast a couple of miles away on the other side of the valley, though I have no idea what is on it.

I am starting to get a feeling that the receiver in the VX-8GR is not much good on summits when connected to a decent antenna. I first noticed odd things with the original VX-8R I had when I tried it out with a SOTA Beams MFD. There have also been several occasions when other people using VX-8 series rigs on summits have failed to hear me, even though I could hear them clearly and in some cases was running much more power than they were. This is quite disappointing. I really like the VX-8GR and much prefer it over the Kenwood TH-D72 which I have been thinking about selling. But perhaps it would be better to keep the Kenwood.

I wish that I had the test equipment to try to compare the strong signal performance of my various hand held radios. HF radios have their receiver performance exhaustively tested and the results of tests by the likes of Sherwood Labs are endlessly debated on various reflectors despite the fact that the only difference it is likely to make is whether you can copy a very weak station right next door to an extremely strong one. But the reviews of VHF radios focus only on matters like the ease of use of the menu system, how many memories it has or how the scanning works.

I think the receive performance of VHF/UHF hand helds is just as important as for HF receivers. If a receiver can’t cope on a hilltop on the middle of nowhere how will it fare with the signal levels in a busy urban environment? Heck, you might be missing vital emcomms messages and not know it! It’s about time the ham radio magazines started publishing blocking dynamic range and cross-mod figures for hand held radios.

On Good Friday I was able to get out and make another attempt at a Summits on the Air (SOTA) activation. This time I was successful, making a short run of contacts on 15 meters into Europe and activating summit W3 / PO-23. It was windy and cold with some occasional snow flurries, but I was able to setup the station in a rock outcropping to shield myself from the wind.

My rocky QTH

My portable station: an FT-817, BLT tuner, and modified Whiterook paddle

At this rate it will take some 250 summits to get to the famed Mountain Goat status, not considering bonus points for winter activations.  There are only 220 summits in the W3 SOTA association, so quite a bit of travel and planning would be necessary to pull this off.  But I’m in no rush :-)

I built this antenna a few years ago and it is about time I posted details about it on this blog.

This is a small loop, that is the length is ≤0.1 of a wavelength, and designed for receive only, not transmitting. The loop is a little more oval than round with the narrower diameter being 36″ and the wider diameter being 40″. A transformer is used to collect the signal and pass it via coax to the receiver.  The antenna shown and described here tunes from  around 3 MHz to 18 MHz.  So it covers 80m through to 20m and of course  the broadcast bands in between those frequencies too.

The schematic of the loop is shown below.

Schematic of the small loop antenna

The main loop is composed of ¼” copper tubing (available from hardware and plumbing stores). The advantage of this type of tubing is that is easy to bend into a set shape and it maintains that shape with just a few fixing points.  If a wire loop was to be made it would require some sort of frame to retain the loop shape.

The capacitor is a variable capacitor from a receiver.  I have not measured the capacitance but I suspect both sections together give a maximum of 300 to 400pF. To increase the range of the tuning of the loop I included a switch to allow either one or both of the dual stage capacitor to be included in the loop.  The picture below shows the top mounting of the loop, the variable capacitor and the switch.  To make easy connection to the capacitor, the copper was squeezed closed at the ends and holes were drilled for bolts. Ring or spade-end connectors can be used to connect wires from the capacitor to the copper tube, and held in place with nuts and bolts.

Note that the copper ends of the loop should not contact each other. They are close in my loop, because of the cable tie mountings on the pine wood, but they do not touch. Electrical connectivity is through the capacitor. To prevent any ‘hand capacitance’ effects when tuning (and hence tuning issues) I added a non-conducting shaft on the capacitor (you can see the brass shaft connector). In my loop the two capacitor sections are joined in parallel to increase the capacitance.  The switch can switch out one section, so decreasing the minimum capacitance and increasing the upper frequency that can be tuned.  A single stage capacitor, without a switch, will do fine, but the higher the capacitance the better.

At the opposite end of the loop a T50-43 toroid has been threaded onto the copper tube.  The toroid has five turns of enameled wire wound on it and it slides easily over the copper.  The copper loop now makes one turn on the loop and the five turns of wire on the ferrite toroid makes the transformer (as shown on the schematic).  This arrangement can be seen below.

The enameled wire ends have had the enamel removed (only the ends) and have been tinned with solder before inserted into the electric wire block, which allows connection to the RG-58 cable. At the end of the cable add whatever connector you need for your receiver.  The photograph also shows the simple L bracket arrangement for holding the pine plank upright on a simple plinth (a small piece of off-cut maple) large enough to stop the loop from toppling over..

The use of the electric connector block is not ideal I find (the enameled wire is too thin) and in future I will probably make something suitable out of some unetched copper circuit board and solder the wire and coax directly to the board.

I am sure there is room for experimentation with the type of mix of the toroid, as well as the number of turns of the enameled wire.  My loop worked satisfactorily so I left it as it is.

How does it perform?  Well I find it always surprises me how well it works for about 10ft of copper tube in a loop, a capacitor and a transformer.  I use this in my basement and can easily tune in stronger stations on the bands.  The high Q of small loop antennas rejects strong out of band stations that can bleed-through in more conventional random wire or even dipole antennas, so improving reception performance. When using the antenna you must tune to the frequency or band of interest and then adjust the loop’s capacitor to tune the loop to the same frequency.  You will hear either a rise in signal strength of a station or background noise if there is no station on frequency.  It is simple to use and it is surprising how it can increase the received signal.

Below are a few recordings made using the loop antenna.  The receiver was the old but excellent Yaesu FRG-7, which for the purpose of this demonstration serves well as a general good receiver, although as you will hear the filtering is wide (‘barn-door’ wide springs to mind).  For each of the recordings I tuned the receiver to the required frequency and adjusted its pre-selector for maximum signal.  What you will hear in each case is the signal and then I will detune the loop one way, then tune it back through the peak to the other side and then returning to the peak of the signal. Recordings were made with an MP3 recorder place in-front of the receiver’s speaker, so you hear what the listener would hear. You should remember this is a 10ft circumference loop in my basement, NOT 100+ft of wire 50ft off the ground.

40m CW recording

40m Phone recording

40m SW broadcast station

80m CW recording

80m Phone recording

Another 80m phone recording

Small loops are directional to the signal source so if you use one you should experiment by turning it.  It may be the HF frequency, or the fact that my antenna is below ground level, but I have noticed not too much of a difference when the loop is turned in orientation.  That said, other small loops I have built for the AM broadcast frequencies, or medium wave, do show a stronger directional nature.

If you want to learn more about small loop antennas I recommend Joe Carr’s Loop Antenna Handbook, published by Universal Radio. That book describes many loops, both large and small and is well worth the read if you enjoy antenna design.  This loop design is not from the book, but I used concepts and theory from it.  The idea of using the copper tubing and the toroid transformer slid onto the copper was my own, although it may not be a novel idea and could have been reported before.

Let me know with a comment if you build and experiment with such an antenna. Share your findings with other readers.

Another QRP To The Field is in the books. Some may wonder why we do it…why spend the time and energy to take our rigs outdoors and operate? Guess if you have never done it, you will never know! The weather made things tough for many parts of the country, but it was sure sweet to live in Florida for this one. Sunny and a warm 87F with a bit of breeze down by the lake made my day a very special one.

K4UPG QRP TTF Lake Fredrica 2011

The bands were fair to poor, but who cared? I was enjoying my hobby, making a few contacts, giving out points to the more serious contesters and spending time in the outdoors. It is a bunch of fun to make contacts with 2 watts and change, use a straight key and launch an antenna up about 35-40 feet in the pine trees.

Between QSO’s the ospreys provided some entertainment as they swooped down into the lake to snag a fish for their dinner while 4 guys on jet skis raced around our little lake. Not a bad way to spend a Saturday afternoon. That’s why I do it! How about you?

On Friday afternoon, I drove over to Broadway Tower Country Park to meet with Dave G4FRE (WW2R) who is in the country for a few days. It was great to see Dave and chat about all sorts of different radio from LF to Microwaves. Dave’s an inspiring guy and I always come away with some project in mind! Recently Dave’s been playing some QRSS using his N4FRE call which has proven quite interesting. Dave also has been trying out one of the Down East Microwave transverters for 70MHz which look interesting (as do the ones for the other bands) and he mentioned that he’d heard an ON station on 70MHz from his Malvern QTH. We talked about EME on bands from 144MHz to 2.3GHz. A very pleasant afternoon sitting in the sun on the hillside, eating ice-cream!It was interesting listening on the handheld and from the car from Broadway – it’s a good location and I heard lots of stations and repeaters I wouldn’t normally here from home. The new GB3GT 50MHz repeater on Clee Hill was S7 from the mobile and I listened to some interesting QSOs on the GB3TF 433MHz repeater.For my birthday, amongst other things, Julie gave me a handlebar bag for my bike. Conveniently, an FT817 and paddle fits in easy, as well as the trusty IC-E92D handheld. This morning I cycled up to Windmill Hill, a couple of miles from here which has an excellent take off in most directions although isn’t actually very much higher than home.Most of my listening was on 28MHz using the FT817 and ATX-Walkabout antennaThe band wasn’t wide open, but I heard XU7ACY from Cambodia, an Indian station as well as some Europeans on CW with 5B4AIX on SSB. Didn’t work anyone but it was most enjoyable. Before leaving the hill, I worked Rob, G4XUT on the GB3TD 433MHz repeater.This afternoon I was excited to work my first Sporadic E QSOs of the season on 50MHz, with QSOs with EA7HG and EA7/G1WUU both in IM87. Also tried some CQs on 70.200MHz, but no luck so far.

On Friday afternoon, I drove over to Broadway Tower Country Park to meet with Dave G4FRE (WW2R) who is in the country for a few days. It was great to see Dave and chat about all sorts of different radio from LF to Microwaves. Dave’s an inspiring guy and I always come away with some project in mind! Recently Dave’s been playing some QRSS using his N4FRE call which has proven quite interesting. Dave also has been trying out one of the Down East Microwave transverters for 70MHz which look interesting (as do the ones for the other bands) and he mentioned that he’d heard an ON station on 70MHz from his Malvern QTH. We talked about EME on bands from 144MHz to 2.3GHz. A very pleasant afternoon sitting in the sun on the hillside, eating ice-cream!It was interesting listening on the handheld and from the car from Broadway – it’s a good location and I heard lots of stations and repeaters I wouldn’t normally here from home. The new GB3GT 50MHz repeater on Clee Hill was S7 from the mobile and I listened to some interesting QSOs on the GB3TF 433MHz repeater.For my birthday, amongst other things, Julie gave me a handlebar bag for my bike. Conveniently, an FT817 and paddle fits in easy, as well as the trusty IC-E92D handheld. This morning I cycled up to Windmill Hill, a couple of miles from here which has an excellent take off in most directions although isn’t actually very much higher than home.Most of my listening was on 28MHz using the FT817 and ATX-Walkabout antennaThe band wasn’t wide open, but I heard XU7ACY from Cambodia, an Indian station as well as some Europeans on CW with 5B4AIX on SSB. Didn’t work anyone but it was most enjoyable. Before leaving the hill, I worked Rob, G4XUT on the GB3TD 433MHz repeater.This afternoon I was excited to work my first Sporadic E QSOs of the season on 50MHz, with QSOs with EA7HG and EA7/G1WUU both in IM87. Also tried some CQs on 70.200MHz, but no luck so far.

For Easter Sunday, Bassenthwaite Rotary Club of which fellow WOTA enthusiast Phil M0AYB is a member put on, in aid of charity, a Felltop Café on the summit of Latrigg, a very minor but frequently visited Wainwright summit just to the north of Keswick. Phil planned to activate the summit while he was there. The opportunity to have coffee and cakes while activating a summit was too good to resist so I decided to pay Phil a visit and do my own activation. The weather played fair and was glorious, too.

Latrigg is an easy summit – really a foothill of Skiddaw – and so it was not too much of a problem for my back which is better but still not fully recovered. The views on the way up are glorious, which is why Latrigg is a popular target for visitors to the area.

From the summit you look down to the town of Keswick, with its lake, Derwentwater, beyond.

Soon after we arrived I heard Richard G1JTD/P on Yoke in the Eastern Fells, and worked him for a summit to summit. Yoke was not a summit I’d have much hope of working from home so that was a bonus.

Olga and I went and got some coffee and Cumberland sausages in a bap from the café. The coffee was excellent. There was quite a queue for refreshments and I hope the enterprise made a lot of money for Bassenthwaite Rotary Club’s charity.

Phil had brought up a 9 element Tonna on a short mast which he was using with an FT-817 running 2.5W. I was using the Nagoya NA-767 mentioned in my previous post on comparing handheld antennas with the Kenwood TH-D72 and 5W output (though not in the picture.) I worked most of the same stations Phil had, and some of them commented that my signal was similar or close to as strong as Phil’s, which was quite gratifying.

This was the first activation I have done with the TH-D72. I have been hoping that in time I would grow to like this radio but I’m afraid it has not won me over. It’s too big and bulky and the case feels plasticky and not rugged enough to stand the knocks and bumps experienced on a summit. I still prefer the VX-8GR, though as noted in previous posts the receiver of that gets easily de-sensed in the presence of the strong signals experienced on a hilltop with a good antenna.