1296 on the IC-705 – You can for about $400

This now ubiquitous IC-705 would have to be one of the most popular radios of its time. Its uses are endless – well almost.

If you enjoy SOTA, parks, microwave or radio in the great outdoors, then this is the radio for you. Having received many accolades, and a long list of positives, some might say there’s one thing missing on the IC-705 and that’s the 23cm band. There’s only so much that you can fit in a small portable radio, and Icom has done a really good job packing in as many features as possible so it’s understandable that the line has to be drawn somewhere.

The good news – it’s a relatively easy addition to the IC-705 with the help of a transverter from the Bulgarian based SG Laboratory.

As a convert to the microwave bands and the Icom IC-705, it’s easy to overlook the 23cm band. 1296 seems to be a band stuck between UHF and Microwave… the runt of the litter so to speak.

With so many IC-705s and other QRP radios such as the Yaesu FT-817 and FT-818, there’s a relatively cost-effective way to add 23cm to the kit.

Introducing the SG Lab 23cm transverter

1296 on the IC-705 doesn’t get much easier than this. This transverter will set you back 156 euros or in round number $250 AUD plus shipping. It also comes with its own PCB antenna to get you going.

This device has a super-hot receiver as well as 2.5 watts out typically. You’re not going to have an EME contact running QRP, but you may just have a QSO over 100km or so… even beyond. If you’re perched on top of a nice hill, a couple of watts is all you need.

All you need to do is to build the transverter into a lightweight self-contained box. This protects the fragile SMA connectors and unit from damage should you accidental;y drop it or run over it with the car.

Get yourself a strong sealed aluminium box of IP-65 specification. IP-65 means rated as “dust tight” and protected against water projected from a nozzle. An IP rating is, in summary, a two-digit code. The first digit establishes the level of protection against intrusion of foreign bodies. The second, the resistance against moisture intrusion.

This 222 x 146 x 55mm box from Jaycar will cost around $40. It’s a good investment to protect your transverter from dust and moisture. Don’t spend $10 less and think you’re getting a bargain.

A self-contained power supply is a must. A power source and all the cables and adapters that go with is one less thing to carry and worry about when going portable. Not only do you not have to find them, you won’t lose them either.

I use three series 18650 batteries which I purchase from Core Electronics.  These 3.7v 2600mAh cost $11 each and will give many, many hours of transverter action. Don’t forget a battery holder too.

While you’re shopping grab a selection of switches, plugs and cables.

You’ll need an IF input connector. I use a panel mount N type to SMA. For RF out, I use a generic SMA to SMA coax that terminates to a SMA panel mount on the top of the box. These cables are a dime a dozen on eBay if you don’t want to make them up yourself.

The external DC input is a 2 pin mic jack. Importantly don’t forget a fuse, and you’ll need 2 DC switches – one switch to select internal and external supply, and another as an on/off switch. Make sure this one has an LED in it so you can see at a glance if the transverter is powered up at night.

A TX LED is a must. In this case, I use a LED with the 12v source and a series resistor to ground. The transverter has a built-in sequencer which has an open collector NPN transistor. It goes low 25ms after PTT.

Finally, the PTT. Using the Send/ALC jack on the IC-705, the radio will give you a TX ground output via a 3.5mm jack. I use this to switch the 23cm transverter, hence the RCA connector on the side marked TX ground. Sure you can RF to switch it, but that’s not the best for SSB operation.

The transverter has a stereo 3.5mm jack. The tip is used for TX and ring is for the sequencer output that I use to drive the TX LED.

The IC-705 is made for portable use and the 23cm band is a great band for hilltop use. The antennas are nice and small, easy to build, and cheap as chips for bits. Try making a bi-quad antenna from the offcuts you have in the junk box.

Finally, the SG Lab transverters are fantastic value for money, technically great and they just work.

Add this project to your ever-growing list of things to make and build. Next time you go out portable, be sure to call CQ on 1296.1. You’ll be surprised who’s listening and who knows, you may get the bug to go higher. 1296 on the IC-705 should be your next project.

If you have a Yaesu FT-818 (or FT-817) transceiver you can still enjoy 23cm on this radio while portable. The accessory jack on the back of the radio is an 8 pin mini-Din. You’ll find a pin marked TX Ground. This is the one to use to get the transverter to go into transmit. The mini-Din plugs are readily available. The image below is from page 15 of the FT-818 user manual.