472 kHz transverter

It seems amazing that I made this transverter 10 years ago! This was me testing it just before boxing. 

Breadboard

The photo shows me breadboarding my 472kHz transverter some time ago when I was fit. This is probably beyond me now as my fine motor skills are far worse. 

I have not ventured into our loft since 2013 and I have lots of amateur gear up there! 

The final design was in QST some years ago and is on my website. It is also in an RSGB book.

472kHz transverter breadboard

This was some years ago breadboarding my transverter for 472kHz in the back of the garage in the old QTH. 

472kHz transverter repairs

Just after tea last night I replaced the PA in my transverter.  It was damaged when my loop was broken a few weeks ago in the gales. Soldering is much harder these days.

Although it is replaced, the antenna current is still low, so more investigation is needed.

UPDATE 0910z:  I tried the earth-electrode "antenna" on a different rig on 160m and was still getting a high SWR. This suggests something is wrong outside still. More investigations needed!

UPDATE 1725z: A visual test indicated nothing untoward. Possibly tomorrow I may replace the wire in case there is something not visible that is wrong. I measured the DC resistance and this was higher than I was expecting, but not exceptionally high.

472kHz - getting started

I have had a great deal of fun on 472kHz even with a very low ERP (10mW ERP). Most nights I run my shack PC on batteries as the SMPSU charging the laptop battery produces an S7 noise floor. Most nights I am spotted in Norway on WSPR. On RX, the PC is good for most of the night on batteries. I use my simple 472kHz transverter (10-15W into 50 ohms) that has been in QST and the RSGB book "LF Today". It is a very interesting band even if your antennas are, like mine, really useless for MF. Compromise antennas really do work!

See https://sites.google.com/site/g3xbmqrp3/mflf/472khz_tvtr

472kHz (630m)

This is a fascinating MF band. I am truly amazed how slow the FCC has been releasing this band and the 136kHz band in the USA. Do they sleep all day?

Simple, small, 472kHz transverter

Even with just 5mW ERP from a just a short baseline earth electrode antenna (earths 12m apart) I have been copied on WSPR more than 1000km away. Copy at shorter range is very easy. I use my transverter with the FT817. The ARRL was due to publish the circuit over 2 years ago, but are still waiting for the FCC release. For goodness sake wake up FCC! You look total fools to the rest of the world!

See https://sites.google.com/site/g3xbmqrp3/mflf/472khz_tvtr .

472kHz transverter

Over the winter I have been using my simple, small transverter for the 630m band on WSPR with my earth-electrode "antenna". It has been widely copied with best DX on TX being over 1000km. 630m is an interesting band.

See my website for more details: http://www.g3xbm.co.uk  (lots of QRP stuff) and specifically  https://sites.google.com/site/g3xbmqrp3/mflf/472khz_tvtr.

M0UKD's version of my 472kHz transverter

It is always pleasing to see other versions of my designs being successfully built. This evening I chanced upon M0UKD's website showing his nice version of my 472kHz transverter. He added an output for a frequency counter which is a useful addition. John gets around 12W out, which is about right.

Another version of my 472kHz transverter (G8AGN)

Emeritus Prof Barry Chambers G8AGN from Sheffield (more usually a microwaves and nanowaves operator) has just sent me a couple of photos of his version of my 472kHz transverter that he's just finished. Unlike me, Barry sensibly put it in a decent sized aluminium box which will help reduce heat affecting the LO frequency stability. 

G8AGN's version of the 472kHz transverter

I've lost count how many of these transverters, or variants thereof, have now been built but there must be a good few in use around the world now. I have still to box up the 137kHz version which was used a few months ago to span 250km with just the earth-electrode antenna.