AmateurRadio.com

I seem to be collecting VHF handhelds at the moment. This is the Motorola Radius GP300 I bought for £1 at the Blackpool radio exhibition yesterday. The seller had quite a number of shiny new-looking commercial handhelds in a heap on the table, all without batteries, which were being sold for £1 each. He told me they were all UHF. Most were Midland radios, but there was this one Motorola which in the end I decided to get because I thought it might be easier to find information about it. I should have got one of the Midlands as well, after all, it was only a quid!

Today I took a closer look at what I had bought, and tried to find out something about it from the internet. From the model number I was able to find out the capabilities of the radio and I actually have a VHF handheld which can cover 144 – 176MHz in 12.5kHz steps, 8 programmed channels with 5W output. I can’t test if it works because I don’t have an adapter for the strange type of antenna socket, but Motorola to BNC adapters are available on eBay. However for the radio to be any use I will need to program it with some 2m band frequencies.

There is information on the web showing how to build a programming interface, but you can actually buy one ready made from Hong Kong for little more than the cost of the parts. The difficulty appears to be getting hold of the all-important programming software. Apparently it was very expensive and Motorola doesn’t turn a blind eye to free sharing of it among the amateur community so I was unable to find any download link.

None of the sites that give information about programming these radios provide any help about how to get hold of the software and they are obviously fed up with being asked about it. So there probably isn’t much that I am going to be able to do with this radio. A pity, as it seems to be well regarded judging by the reviews on eHam, presumably posted by users who got them from dealers pre-programmed with the channels of their choice.

I went for another stroll up Tallentire Hill this afternoon with the TH-F7E. The FT-817 is tied up running my EchoLink hotspot until I can find something cheap I can dedicate to the task – I have my eye on a pair of PMR446 radios that are modifiable to 70cm.

I took along my DIY 2m rubber duck antenna and a “Black Rod” 2m 5/8 telescopic whip that I recently bought on eBay. In case you are wondering, I use an “HT Saver” SMA to BNC adapter to take the strain of the longer whip. But I am seriously considering using the TH-205E for such outings in future, if I can sort out a battery pack for it, because it has a proper BNC antenna socket and is much better suited to use with a large telescopic whip.

The 2m FM channels were not exactly buzzing with activity but I heard the GB3CS repeater 100 miles away and a GW station (Wales) in QSO. I tried swapping the two antennas for a comparison, but could hear nothing on the rubber duck at all. This surprised me, as the last time I did a comparison there was hardly any difference between it and a quarter wave telescopic, and I didn’t expect the 5/8 to make such a huge difference.

The TH-F7E is multimode on receive, so I took a listen on 2m SSB as well. I heard the GB3NGI Northern Ireland beacon much stronger than I can receive it from here. But I couldn’t hear GB3VHF from South East England at all. I haven’t heard it from home at all recently either, although it is supposed to be back on the air after a move to a new location. I guess the new location isn’t as favourable as the one it has operated from for longer than I have held a ham radio license. GB3VHF was the first amateur 2m signal I ever heard, after building my first 2m receiver, so hearing its call in Morse always causes some nostalgia.

I put out several CQ calls on 145.500 and was eventually called by Bill G3WJH in Seaton, only a few miles away by line of sight. I swapped the antennas again, and he couldn’t hear me at all on the duck. Colin, 2E0XSD then joined us, and then we were called by Richard G0IBE/P on Lord’s Seat (a SOTA and WOTA summit) so we all exchanged reports with him for chaser points. Jim G3ZPD from just south of Cockermouth then called in and worked Richard as well. By that time I was getting a bit chilly as it was a lot colder up there than it was at home, so I came back.

On my return I checked the DIY Duck on my antenna analyzer and found an infinite SWR. I pulled off the whip and the copper wire had fractured just about level with the top of the BNC adapter, which is probably the point that experiences the most bending. I guess 22SWG enamelled copper wire isn’t flexible enough to use for a helical antenna. Back to the drawing board.

If you’re a regular reader of this blog you’ll probably have observed my comments about the lack of activity on VHF hereabouts. Even though I can raise three 2m repeaters there is next to no activity on any of them. And although there are several active amateurs in West Cumbria most are “over the hill” from me so I never hear them.

Some time ago I thought about setting up an EchoLink node to make it possible to have some contacts on VHF. But when I realized how much trouble I would have to go to in order to get permission for this I went off the idea pretty fast.

My interest in this basic idea was rekindled when I read recently about the D-Star Digital Voice Access Point. Personally I’m not going to be interested in D-Star until the prices of compatible radios come down and you can buy them from other manufacturers than Icom. Besides, I like my little TH-F7E with its wideband AM/FM/SSB/CW receiver and don’t want to change it for one that doesn’t have that facility. But why shouldn’t I set up a very low power EchoLink node for my personal use so I could make some contacts using my TH-F7E hand-held from round and about the house?

I put in an online application for a Notice of Variation (NoV) to my license to run an attended simplex node – which so far hasn’t made any progress. However, fellow blogger Tim G4VXE writing about his experience with the DVAP mentioned that he made some quick enquiries via the RSGB’s ETCC as to the legality of using the DVAP without an NoV and they were not concerned about DVAPs or hotspots as long as there is no third party traffic.

I presume that D-Star, being digital, knows who is calling in to the system so you can set it so only you have access. With EchoLink you can really only have security by obscurity, using low power, a poor antenna and an obscure frequency so that it won’t pick up transmissions from anyone else. I’m not sure if this meets the official standards for not allowing third party traffic, but my enquiry to the ETCC has also gone unanswered (so far.) I got fed up with waiting and decided to go ahead.

I first tried EchoLink many years ago when it first was announced. At the time I had no way to access the system except direct from my computer. After making a few contacts that way I found that talking to hams without using any radio wasn’t very interesting, so I didn’t use it again.

Even though I am only using RF to make the link of a few metres to the radio connected to the computer, because I am using an actual radio it really feels like I am making a radio contact. I have set up the G4ILO-L node so that it doesn’t allow connections from computer-connected users. There may be disadvantages to this and perhaps some will consider it a bit unsociable but I still feel that using amateur radio at each end of the link is an important distinction that differentiates EchoLink from internet chat. I can still join EchoLink conferences and conferences may include directly connected users so talking to people who aren’t using a radio isn’t completely ruled out.

I dare say there are some who will still consider that making contacts in this way isn’t amateur radio. But the fact that my RF is not going directly from my radio to his is of no great importance as far as I am concerned. This isn’t meant to be a way to explore propagation or work DX. It really isn’t much different from using a repeater.

If I find that it is worthwhile keeping my EchoLink node running then it will create a couple of new radio projects to work on. I will need to make a new computer/radio interface and either build or modify a radio that I can dedicate to the link so that the equipment I am currently using for it can be released for other uses.

Because I signed up for EchoLink soon after it was announced I have a coveted low node ID number: 3098. I have swapped this number over to use for the link. The G4ILO-L node is running low power to a leaky dummy load so it can only be used to contact me. If you have access to the EchoLink network by radio, please give me a call. It would be great to talk to you.

It’s probably a character weakness, but I have always had a tendency to push my luck a bit too far and end up regretting it. That thought was in my mind when thinking about what to do with the Trio / Kenwood TH-205E that I got for a song on eBay. The rig worked well enough already to do what I thought I would do with it if it worked. But I was finding it hard to resist the temptation to see if I could restore it to full working order even though there was a risk that I might end up breaking it completely.

In the end, the temptation to try to restore it won. The radio came apart quite easily – it is a big radio, and fairly easy to work on, though surprisingly for 1986 vintage equipment it uses a lot of SMT parts. The back half is a solid cast metal chassis containing the IF and RF boards, and the front half is plastic and contains the front panel with the control logic. The two halves are linked by two ribbon cables and one had been inserted a bit crooked, which led me to hope that repositioning it might solve the problem of the inoperable buttons, but that proved not to be the case, so the front panel board had to come out.

The front panel board is secured to the front panel itself with a large number of small self-tapping screws. Once they were removed and the wires to the speaker and mic unsoldered, the board came out to reveal the sight shown above. The front panel buttons were not sealed units but capacitive switches operated by contact with the rubber buttons, and they were covered by a sticky mess of gunk – presumably the same stuff I had found on the outside of the case which a couple of readers informed me was a cleaning agent used to spruce plastic items up prior to sale. This hadn’t just distributed itself over the switch area, it had even penetrated through some of the vias to reach the other side of the board. What a mess!

Olga found me a few small pieces of rag and I went to work with some white spirit from the garage. I eventually managed to clean most of it off. My fears about causing even worse damage were raised when the LCD display fell off. It didn’t seem to be attached to the board and had perhaps become stuck to it with some of the gunk. However when I reassembled the radio I just rested it in place while I fixed the PCB in place and it still worked.

There was no way I could test if the switch contacts were clean enough without reassembling so eventually I decided that it looked good enough and back it all went. I applied power with trepidation. The display lit up and I could hear hiss in the speaker. I then pressed the Offset button and was able to select repeater shift! The Scan function set the receiver scrolling slowly through the entire 2m band in 5KHz steps – very useful that! I was also able to program and recall frequencies in the three memories, although the memory buttons still need a bit of persistence to get them to work. It isn’t worth taking it all apart again just to try to improve that.

While I had the rig apart I took the opportunity to reset the power levels to give 5W on High power with a 13.8V supply and 0.5W on low power. Some previous owner had probably tweaked the power controls to give 7W out. No point in stressing the probably irreplaceable power transistor for a barely detectable 1dB or so of extra power. Then I put it all back together. Job done, and the TH-205E restored to full working order. I was feeling pretty chuffed.

As usual, there was no-one around on any of the simplex channels to do a test with but I was able to access the GB3DG repeater and even GB3LA on 145.7125 (a 12.5kHz channel) by tuning to 145.715.

I’m starting to feel a bit of affection for this big old radio now that I’ve made it as good as new. I’m thinking that it would be worth trying to resurrect the NiCad battery pack, which at the moment is showing a dead short. But there I’m really stumped, as I can’t see a way in. Clearly the plastic case is made in two halves, but sticking a screwdriver in the crack and twisting is just going to chew up the plastic. Anyone know if it’s possible?

Whilst buying on eBay can sometimes result in a piece of junk, it can also produce the occasional lucky find. The radio pictured on the right is my latest auction success which arrived this morning. It is a Trio / Kenwood TH-205E of 1986 vintage which was being sold as for spares or repair. It cost me all of ten quid ($15 for my US readers), four of which were for postage.

When it arrived it was a bit oily, for some reason, but a wipe over with some tissues took care of that. From the front it looks almost like new – no scratches or signs of wear on the markings or buttons. The rig has obviously had an active life though as on the back the paint has worn away and the serial number plate and the warning notice on the battery pack have been polished almost clean of lettering.

The seller stated that they could not get the radio to charge up, which is no surprise, as for 24 year old NiCads to still retain a charge would be nothing short of a miracle. I applied 9V of external power, switched on, and was pleased to see “144.000” appear on the display and hear the hiss of an unsquelched receiver from the speaker. My initial delight at having acquired a worker was short-lived, however, as the frequency display failed to respond to the up/down buttons and the squelch did not seem to work either.

After a while spent pressing buttons in the faint hope of getting the frequency to change, it suddenly did increment a few steps and the squelch also operated. Then the radio gradually became more responsive to the buttons and I was eventually able to persuade it up into the 145.500 region. I connected my QRP power meter and was delighted to observe that the TH-205E was putting out a good 5W in the high power position and 1W in low power. I could also receive the signal on the TH-F7E standing nearby, which was somewhat dwarfed by its older sibling. I’d forgotten hand-helds were still this chunky in 1986!

I connected an antenna and found that I could receive all the local repeaters, so sensitivity is acceptable. The TH-205E will only do 5kHz steps so it isn’t suitable for 12.5KHz channeling, but the receiver is broad enough to receive the GB3LA repeater on 145.7125 when tuned to 145.710 with perfect audio. There is no CTCSS, though there is a tone-burst switch (which I haven’t tested.)

Apart from the up/down frequency selectors the only other front panel button that appears to work is the Lamp button which backlights the LCD display. I can’t activate the repeater offset or program or recall any of the three frequency memories. Possibly these buttons will eventually spring to life after repeated pressing. Otherwise it may require a look inside to see if it is possible to clean the switch contacts. But to be honest I’m not all that bothered, as I’m unlikely to be using the TH-205E on any repeaters.

The most I hoped for when bidding for this was a radio that could easily be got working and could then be put to use as a dedicated rig for APRS on 144.800 or something similar. The least I expected was something I could cannibalize for £10 worth of useful parts. So already I have got more than I hoped for!

The success of my project to make an FM version of G3XBM’s Fredbox was always going to depend on the receiver. The Fredbox receiver is a simple three transistor super-regenerative design. This is the only practical way to make a receiver small enough to fit in a hand-held case. It is also the only cost-effective way to do it, because making a conventional double-conversion receiver with crystal control just wouldn’t be worth it for such a project.

What I didn’t know were a) would the super-regenerative receiver work with FM signals (the original Fredbox was designed for AM) and b) would it be sufficiently stable to stay on frequency without the benefit of crystal control? However, what I didn’t give too much thought to was the possibility that I wouldn’t be able to get it to work at all.

Because this is a VHF circuit I didn’t think I could try it out on the breadboard so I made it up directly on to Veroboard. The layout is pretty similar to Roger’s original layout from what I can tell from the pictures on his website, although I think he made an etched circuit board, something I’m not able to do.
I drew up the layout using a bitmap editor. This shows the components from the top view. The large outline components are the Toko S18 inductors, and the red lines are wire links below the board connecting the ground traces. The schematic for the receiver part of the Fredbox is shown below. As with the Nano-40 I used an MPS13 in the audio stage in the hope of getting a bit more audio gain.

I applied power and expected to hear a hissing sound in the earpiece which stops when a signal is tuned in. However I heard nothing at all. The audio stage appears to be working, as I can hear a faint buzz if I touch something metal to the input.

Alan, VK2ZAY had a lot of trouble getting the receiver to work as well, and he is an experienced constructor who knows what he is doing. I suppose this should have warned me off trying this project. Alan replaced the axial choke for L3 with half a dozen turns of wire on a ferrite bead, and I did the same, but to no avail. I also substituted a variable trimpot for R2 which in many other super-regenerative receiver designs is a variable regeneration control. But no matter what the setting of the pot I could not get any regeneration to occur at all.

I think my FM Fredbox is about to become yet another abandoned project. 🙁

A few weeks ago I made a rubber duck helical antenna for my TH-F7E. I didn’t get around to writing about it at the time, plus it took a while to get some reports of its performance.

Well, it works extremely well, and I have just added a description of how to make it to the main G4ILO’s Shack website. See A DIY Ducky for 2m.