Radio Kits Explorer SSB/CW transceiver

An interesting new rig has been designed by Steve G6ALU and has recently been released for general sale. Steve G6ALU is the guy behind the famous MKARS80 LSB rig.

I found out about the Explorer rig in December and I thought it would be something nice to spend my Christmas funds on. I had been looking to get a QMX but it seems to me like the QMX is still very much in the development stage at this point.

The Explorer kit cost £120 for all options shipped to my door - I ordered on Sunday and received it on Tuesday!

The build was quite lengthy, I spread it over several days, but everything went together perfectly and there were no issues. There are a lot of parts!

The frequency error was a couple of tens of Hertz, so hardly worth bothering with calibration.

The audio from the little speaker is surprisingly good and there aren’t any annoying rattles as experienced with some other transceivers.

The CAT function worked well - I’m not good with computers but I got the rig talking to WSJT-X with no trouble via the built in USB and after plugging in a 3.5mm audio cable to the computer soundcard I was instantly receiving FT8.

The radio just worked - there literally was no issues with the build at all.

I took the Explorer out today to Pendle Hill G/SP-005. I’d chosen to build a 20m version so coupled it up to my SOTAbeams BH3 dipole. I self spotted for SSB and first in the log was Lars, SA4BLM. Lars commented that my audio sounded ‘DX’, so I guess quite thin with no bass. I guess I don’t need voodoo audio when I’m trying to work through a SOTA pile up. My mic is home brew using a bit of electrical conduit and a cheap mic capsule obtained in a bagful from the far east. I worked several callers including Gene, NT2A, in NY. Moving to CW I noticed that although the CW narrow filter helped a bit, it was still a little bit wide. The filter is audio based, so you can’t really expect crystal or DSP kinds of narrow. I was able to work quite a few with CW, including an S2S with HB9DGV/P on HB/BE-156. The keyer has three modes - straight, Iambic A and Iambic B. Most of my rigs use Iambic B, so I set the Explorer to Iambic B and found the keyer to be quite nice to use, although the speed reported by the RBN doesn’t seem to exactly tie up with the Explorer setting.

Power output is adjustable in the field and independently for SSB and CW, it’s just a menu setting. I found that the Explorer is easily capable of >5W.

My Explorer consumes the stated 150mA during receive.

One niggle- the VFO tuning function is rather inconsistent. The only mechanical control on the entire radio is a rotary encoder. The tuning control has a smart feature that increases the VFO step size the faster you turn the knob, only it doesn’t seem to work consistently. The tuning has a habit of not doing much and then jumping a large amount. Steve is aware of the issue and I’m sure that with some clever bit of code the debouncing can be smoothed out. The radio remembers the last powered up state, so rather like an FT-817, I set VFO A to the SSB end of 20m and VFO B to the CW end. Only one mode can be selected unfortunately, so you still have to change to SSB or CW in the menu after swapping VFOs. The built in USB port will presumably allow firmware updates in the future.

I am very happy with the kit, it is all that I hoped it would be. A manual and other details can be found on Steve’s website here - Radio-Kits - Explorer QRP Transceiver

73, Colin


Another fine looking ‘traditional’ superhet transceiver. Shows some interesting design choices, including an LCD (to minimise noise), BC547s in the RF and IF gain stages, and a discrete diode ring mixer as product detector. Should be a very ‘clean’ sounding receiver. The IRF510 PA keeps costs down and is easily replaceable. Nice job!


Colin, You’re the proof of the formula:

No. of radios required =n+1, where n=radios

Great build though and looks great value for money for the performance. Look forward to hearing of future developments. I’m surprised it is mono band though.

Did you have John Motson up on the hill with you? :point_down:

love the mic.


Many thanks for the very interesting and informative review Colin. As an “old” constructor, I was pleased to see it was not a kit of of SMDs, such that even I might be capable of constructing it. I’m sure you’ll have fun with it.

As for Fraser’s comment relating to the number of radios required, I seem to have an error in the calculation at my end such that n-1 is becoming the norm. :joy:

73, Gerald


Looks very nice! I had a look at the web site but couldn’t see any physical dimensions, how big is it and how much does it weigh?

Mine weighs 472g (roughly 1lb)

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Making the rig multband would add to the complexity. Ideally you’d need a band pass filter (RX) and low pass filter (TX) for each band. There can be certain combinations were bands could share filters though. You’d need a means of switching filters- relays or diodes. I think the goal of the Explorer was a radio kit, with performance, that an average ham would have a high chance of been able to put together successfully.

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As a QRP monobander, the Radio-Kits Explorer is unfortunately on a par with the KX2 in terms of power consumption and weight - so the justification and satisfaction has to come from building it yourself and the very clear price difference.


Well, yes!

The components used have clearly been selected for ease of home construction. The selection of components therefore dictate the size and weight of the finished radio.

Yesterday an over-enthusiastic dog got tangled up in my antenna lead and dragged my radio about 2m. If it had been a KX2 costing a 4 figure sum, I’d have been a bit worried. Taking a radio worth about 1/10 of the cost out in the hills isn’t nearly as bad!


Hey Colin, thanks for posting this - great photos!

I’ve got one in the post - it should be here today or tomorrow. It’s good to see that the kit went together well. I have no electronics knowledge, but I do like to build simple kits and so far have managed to do two QDX, a QCX and a few other bits and bobs. I’m looking forward to starting this one.

I bought it to use at our holiday home (static caravan) in Scorton - not too far from you in Lancaster.

Hope to catch you on-air sometime.

Kind regards,

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Just finished my Radio-Kits Explorer. Wrote a review with pics here, for anyone interested in the kit…

73, TOM, M7MCQ


Great blog Tom. :ok_hand:

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Interesting to read about a different builder’s experience. I didn’t bother printing out a manual, I just built from my phone screen. Everything was logical, there were just a lot of components!

I’m looking forward to using this rig for SOTA in the summer months.

Congratulations on a successful build.

73, Colin

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This is reason I’m considering this, probably the 40m version ! … here the spaniel is under strict instructions to stay on the carry mat away from @GW4BML’s KX2

Very interesting post ! It looks fun, but let me comment after i get nowhere as my soldering skills screw something up…

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