Saturday, 3 October 2015

The URMSTON Regen Receiver

Now that the cat has been let out of the bag on the Kanga website, I guess it is OK to tell you - the second of the two receivers I was playing with a few weeks back is now revealed to be a collaboration with George, g3rjv, and friends at the G-QRP club...

As you see above, the receiver looks pretty in her first production build (even though I say so myself).

The new receiver has been developed particularly for the Buildathon at this year's Rishworth mini-convention, so the PCB layout has been made with special attention to the needs of first-time builders. There's lots of space between the components and plenty of elbow room for the soldering iron - no surface mount technologies here!

Also, I wanted participants at the Buildathon to be able to put together a practical receiver with controls on a real front panel. I  like the form-factor of some of Tim Walford, g3pcj's kits - but didn't think that a fixed front panel would be the best option for a raw tyro in a Buildathon, where time is tight and quick access for trouble-shooting might be invaluable. So I came up with a design that could be made in two parts and quickly plugged together - or pulled apart.

The result is seen here from behind...

The system relies on simple latching connectors for the controls (the female headers are supplied with lengths of cable ready-connected in the kit, so the builder only has to trim to length and solder to the controls) and brackets to fix the main PCB to the front panel PCB. But what could I use for the brackets?

Well - modesty almost forbids me from telling you,

After looking around the workshop for a while and scratching my head, I settled on the idea of using these abominations...

They are - I believe - called "modesty blocks" and they stand in place of carpentry skills in this era of particle board furniture.

They are available in a bag of a hundred for the price of a pint of fancy beer in a city-centre drinking establishment - which is to say they cost a few pence each, retail. They are made of a hard plastic and have two holes on 18mm centres in one plane and a single hole, midway between the other two, normal to them.

They make perfect brackets for the two PCBs of the little regen...

Here's a rather immodest view of the assembled unit...

In times of trouble, unscrewing two screws and pulling off five header connectors will separate the two sub-assemblies. But when fixed together, the blocks make the front panel perfectly rigid.

The front-panel ground-plane is connected to the rest of the receiver via one of the leads - without which the notorious hand-capacitance allows the unit to revert again to its secondary role as a Theremin!

The receiver is great fun to operate - pulling in AM, CW and (if you are patient and skillful) SSB signals on a piece of wet string. It is very sensitive. It is also VERY unlike the other types of receiver we are more used to playing with today. Fortunately I had developed some experience with regens from playing with my Paraset, but for regen virgins, this could be a surprise.

It has been a joy to be working directly with one of George's designs, on an "official" commission from George and Graham at the G-QRP club.

As a further joy (or embarrassment), Dennis at Kanga has named the kit The "URMSTON" - which is the postal town near which I live. Presumably the word is stuck in his mind after mailing so many things to me.

The kit is going to be launched at the G-QRP Buildathon on Friday 23rd October and will be available for general sale at the mini-convention on Saturday 24th and thereafter from Kanga.

I am pleased that my two receivers will be "cannon fodder" at the two big forthcoming Buildathons at UK Radio events this month - I only hope the participants will be pleased too!

...-.- de m0xpd


  1. Paul, mock ye not the humble modesty block. They make great insulators for wire antennas and for the past 25 years I have used them as pulleys to hoist up said wire antennas. Low friction, last in the sun for years, they do not jam like real pulleys and they are very cheap!
    - 72/3 Tony G4WIF

  2. Modesty blocks may well substitute for skill and certainly look horrible, but look in any Elecraft K1 or K2 and they are what holds the case together. Theirs are small neat and made of aluminium (aluminum??) but they do a great job and are perfect in that role. You did well there Paul!
    Les g0nmd