How small is small?

Foundations of Amateur Radio

I've owned a Yaesu FT-857d radio since becoming an amateur and at the time I was absolutely blown away by how much radio fits inside the box. It's smaller than most of the commercial radios I'd seen when I bought it.

I came across a video by Michael KB9VBR, the other day showcasing a wooden cigar box with a complete, well, almost complete POTA, or Parks On The Air, activation kit. I say almost, since Dave KZ9V, the owner of the kit, points out that the box doesn't contain an antenna.

It made me wonder how small is small?

According to RigPix, the lightest transmitter on an amateur band, in this case, the 5 GHz or 5cm band, is an Amateur TV transmitter. Weighing in at 3.9 grams. The Eachine TX-06 is capable of FM with about 18 MHz of bandwidth with an audio sub-carrier.

Of course, that's not a transceiver, but I thought it worth mentioning in case you needed an excuse for something tiny in your shack, besides, as far as I can tell, there's never too much Amateur TV in the world.

I've built a crystal radio on a breadboard which is tiny, but it doesn't transmit, so to set the stage, I think we need to limit ourselves to transceivers, that is, a device capable of both transmitting and receiving, on amateur bands.

Before continuing I'd like to express my thanks to Janne SM0OFV, for the rigpix.com database that he's been maintaining, in notepad, since 2000. Without the invaluable information documented for the currently 7,512 radios, I'd be spending an awful lot of time hunting for information.

Moving on, the FaradayRF board is a transceiver, capable of using 900 MHz or the 33cm band. It comes in at 30 grams, but without a computer it's a circuit board with potential.

The PicoAPRS by Taner DB1NTO, is a 2m transceiver specifically for APRS, weighs in at 52 grams and similar in look and a third of the weight of an Ericsson T18 mobile phone. Speaking of mobile phones, the PicoAPRS does WiFi and Bluetooth, can pair with your phone and act as an AX.25 modem. I'll confess, I'm drooling.

Moving right along, for 70cm there's a Rubicson Walk 'n' talk, weighs in at 65 grams. Mind you, the RigPix database puts this under the "License-free / PMR446" section which comes with a sage warning, check your local laws before transmitting.

There's a few Alinco DJ-C models for different markets that operate on 2m or 70cm, weighing in at 75 grams.

The ADALM Pluto weighs 114 grams, but you'll need a USB power supply of some sort to make it do anything. It can operate between 70 MHz and 6 GHz, but the user interface is limited to a single button and LED, so if you want to interact with it, you'll need some external technology.

Moving on to HF transceivers, weighing in at 199 grams, without the bag, but all the options, is the Elecraft KH1. Transmits on 40m, 30m, 20m, 17m and 15m and receives between 6 and 22 MHz. It's CW only, but you can receive SSB.

If CW isn't your thing, RTTY and PSK can be used on the 40m band with a Silent System Handy PSK 40. Presumably the Handy PSK 20 runs on 20m. Both weigh in at 250 grams.

The Zettl P-20xx SSB does SSB, AM, FM and CW, transmits on 10m, 11m, 12m and 15m as well as the MARS frequencies and receives between 14 and 30 MHz, weighs 300 grams. Even comes with CTCSS.

Another Elecraft model, the KX2 weighs in at 370 grams, does 80m to 10m and the WARC bands, does SSB, CW and data. Mind you, you'll also need to add the weight for the microphone and paddles, and factor in a computer if you want to do more than PSK and RTTY.

The Expert Electronics SunSDR2 QRP does 160m to 10m, the WARC bands and 6m. Weighs in at 500 grams, has a network port and two independent receivers. Operates at 5 Watts. There's no user interface, unless you count the reset and power buttons, so I'm not sure if it can operate on any mode with just a microphone, but given the "Depending on software" disclaimers throughout, I'm going to guess you'll need to bring a computer to make it sing.

The Risen RS-918SSB does all HF amateur bands between 160m and 10m, has a user interface and display, even a big tuning knob, has built-in FreeDV and does FM, SSB and CW. I'd hazard a guess that this is the lightest self-contained transceiver that you can take out on a POTA mission to a park. Weighs 623 grams and comes with an internal battery.

The Elecraft KX3 also does 160m to 10m, and 6m, with a 2m option. Weighs in at 680 grams, but that doesn't include any options.

And finally, we pass 1 kilogram and hit 1,100 grams and discover a radio that does all bands and modes, the Icom IC-705 with a battery, but no antenna.

The Yaesu FT-817, FT-817dn and FT-818 weigh 70 grams more, but that weight includes both a battery and antenna.

Of course there are other options.

For example, there's the (tr)uSDX by Manuel DL2MAN, and Guido PE1NNZ, does 80m, 60m, 40m, 30m and 20m, CW, SSB, AM and FM. Comes in a kit, weighs 140 grams. It's not on RigPix, so I only know about it because it was mentioned by Dave KZ9V.

Similarly, I bumped into, wait for it, a single transistor transceiver called the Pititico, in case you're wondering, Pitico means very small in Portuguese and Pititico means very very small. Designed by Miguel PY2OHH, it comes in various revisions, including one by Ciprian YO6DXE, also known as DX Explorer on YouTube, complete with a circuit board design, and with some modifications can do AM in addition to CW. It's also not in the RigPix database and I have no idea what it weighs.

The point being that this rundown is intended as a starting point to explore how small you can really get and still activate the Park or Peak you intend to.

While you're contemplating weight, remember to account for power, control, and most importantly an antenna or six.

Again, big thank you to Janne SM0OFV, for the rigpix.com website. Also, thank you for the memories of the Spectravideo SV-318 and SV-328, the last time I bumped into one of those was in 1980-mumble when I was working in a computer shop on the Haarlemmerstraat in Leiden, Mr. Micro Zap, if you're curios.

What lightweight adventures are you looking for next?

I'm Onno VK6FLAB