Tuesday, July 03, 2012

An APRS handheld to play with....a look at the Kenwood TH-D72E

A few weeks ago, I mentioned when I was talking about how you couldn't really have too many handheld radios, I said that I would like to have a play with one of the GPS equipped, APRS handhelds. I didn't say so at the time, but very shortly after that, I did have that chance!

I was doing some work on some APRS equipment for a review for Practical Wireless that you'll be seeing soon in the magazine. However, along with what I was reviewing, David Wilkins G5HY of Kenwood Electronics very kindly popped a TH-D72E into the box of gear to look at. David said it was partly a safety net to be sure that I could do some full tests on the other equipment, but very kindly that he'd also seen my blog!

Well! I can now admit that the TH-D72E was the very first thing unboxed! It's a nicely sized handheld and I found it easy to use. I used it mostly in its' APRS capacity, although I did play around a little with it as a regular handheld and used it through the GB3UK repeater on Cleeve Hill. That worked fine and I found I was able to get a good solid signal into the repeater at 5W.

What I was really intrigued about was whether the MB7UC APRS digipeater on Cleeve Hill on 144.800 would hear my packets. I was pleased to find that the GPS locked up pretty quickly and established my position, even inside, though some times it would take a minute or more which was no big deal. I set the beacon so that it would be transmitted once every half hour (that felt right for this experiment).I left the handheld on the upstairs windowsill that 'sees' towards Cleeve Hill. Although I received the odd packet from MB7UC and it received the odd packet from me, there was not much. This illustrated the difference between a handheld antenna and having a collinear at 30 feet - on which the digipeater is very loud indeed.

I took the TH-D72E over to Cheltenham when visiting my Mum and was excited to get lots of packets through the handheld, digipeated through MB7UC including some from a Search and Rescue boat in the Severn Estuary! Very cool! And of course, being closer to the digipeater it happily heard my APRS packets and digipeated them.

How could I make it better from home and get a bit more coverage? Well, I then setup the Kenwood TM-D710E which I had as part of the review work as a digipeater and connected it up to the collinear. Now when I went out for a walk with the TH-D72E and it sent an APRS packet, the digipeater at home would repeat it and it could then be heard by the digipeater on Cleeve Hill - and a couple of others too! It was good to hear the satisfying beep of the handheld as it saw My Position being digipeated through other APRS digipeaters. Fun to come back and look on APRS.FI and see where I had been!

The Smart Beaconing feature on the TH-D72E was good and sent a beacon at appropriate intervals depending on how fast I was moving (on foot or on the bike - don't worry, David - it was a mountain bike - not a motorbike!).

Lots of fun! The only thing that was slightly disappointing was the lack of a good APRS digipeater in this area - which would make the experience even better! But that's hardly the fault of the TH-D72E! I also experimented with sending messages to and from other APRS stations which was good - and even sent a message to my pal Steve, WG0AT in Colorado - and his goats, Peanut and Rooster of course!

Battery life was pretty good, although not as good as some of my other handhelds. It was in line with the manual though and I think the reason for the relatively short time (between 5 and 10 hours between charges when APRS beaconing) was not only the regular beacon, but also the GPS which are pretty notorious for sapping battery life (the iPhone comes to mind!).

The TH-D72E is a 'substantial purchase' at over £400 - but there is a lot of additional technology compared to a more standard handheld - the packet TNC and the GPS all built into a small package that will easily fit in your pocket. This is surely how the mainstream manufacturers can compete, by putting extra value technology such as APRS/GPS or Digital modes like DSTAR - into their products. At £400 you really have to want to play APRS and have a nice GPS on your radio - but I can certainly recommend the TH-D72E - I thoroughly enjoyed playing with it and I'm sorry to have to give it back! Thank you, David!

Now what should I casually mention that I'd like to play with next......


Stewart C. Russell said...

I found that the stock rubber duck really limited the range. Replacing it with a longer dual-band whip allowed me to hit distant repeaters with no problem.

It would be nice if the GPS did a warm start, rather than a full cold start every time the HT is powered on. It would allow faster position reporting.

I do like the HT, and I'm glad I bought it. It works well with the free Chirp HT programmer, and as a bonus, works with the cheap Wouxun headset accessories.

73 de VA3PID

Tim said...

Hi Stewart - I wondered about that! Yes, probably a good long whip on it would have helped my APRS coverage an awful lot.

Thanks very much for the feedback.


Alex Hill said...

APRS has taken off quite a bit in Cumbria and Dumfries due to a few iGates springing up here and there as well as the 'UQ' digipeater that has excellent coverage.

We are also lucky to have all the summits as objects so SOTA & WOTA activators can make the most of the QRU servers maintained by the WOTA team.

I find the messaging very useful and have had a couple of useful ones from a local ham telling me I'd walked past a certain summit! I'm not the only one who's done it.

I use a VX8-GE which takes a bit longer to get a fix but is smaller than the Kenwood but both are fairly useless without the iGates and digipeaters about. The more the merrier.

Xastir (the linux APRS application) works on my raspberry pi with a bit of fiddling so its even more available.

Anonymous said...

Hi Tim

I own the Kenwood TH-D72 and have found the stock duck to be poor.


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