Resonating the VLF receiver loop

Today I've been resonating my receiving loop to see if this improved things. Well, I tried it - no better. Then I improved the active high pass (50Hz) filter which got the mains hum down some more, removed an audio gain stage in the RX just leaving 2 common emitter stages. With this, 4W TX, and the loop resonated around 2kHz I did a further walk-about test. 0.42kms was the limit of range. S/N better and 50Hz hum not a problem even close to cables. The RX needs some more gain and narrower selectivity.

More earth mode experiments at 1kHz

This evening I extended my TX electrode spacings by connecting one end to the copper pipes in the house, almost doubling the effective TX baseline to about 20m. With this, my "earth mode" signals were much stronger and I was able to cover further than before in a "by ear" walk-about test around the fields locally.  Ultimate range tonight was 0.4kms using 4W (probably less as the TDA2003 was hot and probably turning down the power) and receiving on an 80cm 30t loop, active HPF, small AF amp and crystal earpiece.  Range was limited by 50Hz mains hum and background sferic noise. I must retry this set-up with my HF up-converter and FT817 this week, which has good rejection of 50Hz (and its harmonics) as well as a narrow CW filter.

San Marino on 6m QRP

Just worked T77C on 6m Es with QRP SSB. I think I've worked this station some years ago but it is one of the less common Europeans and a first for this season.

6m Es

Only had a brief chance to operate today as I was busy in the garden then out at a BBQ in the hot sunshine, but managed to work some 6m QRP Es this afternoon. Although I worked some DX last week when out pedestrian portable, this was the first 6m Es QSO this season from home. In the coming weeks we can expect 6m to be open for DX most days.

Tame Robin

Whilst out portable in Devon last week I was "visited" by this very tame robin who came so close he ate an ant from my hand. I was able to take a really close-up picture from about 20cms away. In the USA the American robin is a totally different, and larger, thrush sized bird. In the UK it is not uncommon for robins to be so tame they will come very close to you when gardening and they can be trained to eat from your hand. There was a good book called "The Life of the Robin" by David Lack published by Fontana in their New Naturalist series. This is no longer in print.

Pedestrian Portable webpage added to site.

See http://sites.google.com/site/g3xbmqrp/Home/portable for my thoughts and tips on portable HF SSB DXing. If you have further thoughts or tips please let me know. Also, I'd be interested to hear about results YOU have had with true handheld HF DXing.

M0BMU's latest complete 8.97kHz Portable Receiver

Jim Moritz M0BMU has updated his loop/preamp circuit for 8.97kHz turning it into a complete direct conversion receiver for 8.97kHz. He posted this on the LF reflector in the last few days. I have added this to my sub-9kHz website (scroll down for Jim's description and schematic on the webpage. See http://sites.google.com/site/g3xbmqrp/Home/10khz

Further 8.97kHz DX tests from Germany

DK7FC conducted more tests on 8.97kHz last weekend. Best DX was 300kms mainly because the noise levels are now higher than in the earlier tests. However it allowed Stefan to test some new equipment successfully.

Portable clifftop DXing

No updates for the last week as I was on holiday and out of internet contact. This last week I had a couple of chances to do some handheld SSB DXing with the FT817 from a Devon clifftop near Thurlestone. Although I think I stood a chance working LU2DO last night (I called and called and no-one else seemed to be hearing him), I did manage some European QSOs on 15m (HB9CVQ and a DL) and 6m SSB (IW0HLE) when running just 2.5W to a small whip antenna. I use an 8 foot long dangling wire counterpoise which helps a lot. On 6m I was just using the short helical supplied with the rig and only about 20cms long! Clifftop portable sites are magic with a decent low angle take-off, not that this matters so much with sporadic-E. In the past I've worked South America and the USA with handheld SSB.

IC7000 reliability

Some people have had issues with the reliability of the IC7000 driver transistor which gets too hot and can self-destruct. SV8YM has some modifications to help, putting improvised heatsinks on the effected devices so they run cooler. See his blog at http://sv8ym.blogspot.com/.  This is a rig I've considered purchasing but I have been concerned about the heat in such a small box and consequential reliability.