25 Aug 2008

Simple 432MHz operation webpage

Just added a new 70cms web page to my site at http://www.g3xbm.co.uk .

19 Aug 2008

501kHz tonight

Heard G3KEV calling CQ on 501kHz CW tonight and listening for crossband QSOs on 3533kHz. Although I called him a few times on 80m he did not hear me. Also heard (for the first time) was G3DXZ also on CW. Both stations were RST549 on the FT817 and random 15m endfed wire.

17 Aug 2008

6m and 10m lively today

Both 6m and 10m were lively in Europe today with quite a few QRP QSOs made on both bands via sporadic-E. Nothing heard much beyond Europe though apart from 6V7L being called by many on 10m.

16 Aug 2008

Home Base 10 - webpage link fixed

The link to the Home Base 10 (10m halo antenna) on my webpage http://www.g3xbm.co.uk went AWOL last week. This has now been fixed. The antenna is fully described in September 2008 edition of Practical Wireless p38-40.

6 Aug 2008

Good 6m opening tonight

What an evening! Only worked one EA station on 6m QRP but heard some amazing DX. Firstly D4C Cape Verde Is (working piles of Europeans on CW) who was audible on the vertical colinear on the side of the house at 539 at best. Also heard was Lefty K1TOL in Maine, USA who was peaking 569 on the same vertical antenna. Really thought I had a chance of working him again with 6m QRP but was not so lucky this season.

Home-base 10 antenna - QSO with USA

10m opened up to the USA this evening and I managed to get RS53 from N2MM in New Jersey with QRP SSB to the Home-base 10 10m halo. This antenna is really working very well indeed. There is an article showing how to build this antenna in Sept 2008 edition of Practical Wireless.

5 Aug 2008

G3XBM website updated

My website at http://www.g3xbm.co.uk was updated today with a page on the Moxon 70cms antenna including a diagram and a few pictures.

3 Aug 2008

70cms Moxon results


Well, the 2el Moxon made from my wife's coat hanger was tested in the 432MHz low power contest today and it worked very well considering how tiny it is and how it was made! Best DX was F8BRK at 326kms who gave me a 519 report. In all 10 QSOs were made in a few hours of operation with 5W from the FT817. A total of 8 QTH locator squares were worked in very dismal conditions and rain.

2 Aug 2008

70cms Moxon 2el yagi

There is a 432MHz low power contest this Sunday, so I have made a small 2el Moxon yagi to use /P with the FT817 in the contest. I have no idea if I will work anyone with it. It was built using one of my wife's coat hangers. If you hear G3XBM/P be sure to give me a call. I shall be operating from JO02CC or JO02DD square in East Cambridgeshire. Both have clear take-offs to the north round to the west, but not so good to the east.

26 Jul 2008

DSB10 - more progress

I have now breadboarded the 10m DC receiver for this rig using a single balanced mixer with 2 diodes followed by two stages of audio. It works well and was pulling in plenty of stations in the IOTA contest this weekend on both SSB and CW without any sign of AM breakthrough. I think the secret is plenty of LO injection to switch the well balanced diodes hard.

21 Jul 2008

10m DSB Rig - started at last


For some time I have been toying with the idea of building a simple but effective 1-2W DSB transceiver for 28MHz. Well, this weekend I made a start by breadboarding the transmitter up to, but not yet including the final PA stage. The 2N3904 has been used throughout plus a couple of 1N4148 diodes (which seemed well matched) for the TX balanced mixer. Output from the balanced mixer was sub milliwatt so a couple of linear stages lift the output to around 50-100mW pep. With a single 2N3866 PA stage this should take me up to the 1-2W pep level.

Next stage to breadboard is a mixer-VFO. I am thinking of a 20MHz xtal oscillator (because I have a crystal) and an 8MHz VFO. Ideally I'd like a higher xtal oscillator so the VFO is lower in frequency and more stable.

The RX was breadboarded last week and uses a single balanced diode mixer followed by 2 stages of audio. This works really well with no sign of AM breakthrough at all.

15 Jul 2008

Pipit20 rig on air


This last week I have been building again. Not much, just another DC transceiver built ugly style. The rig covers 14048-14070 VXO controlled and puts out about 500mW using the OXO design. It uses an SBL1 mixer on RX followed by 3 stages of AF gain. Only station worked so far is M0BXT but hoping for some Europeans maybe at the weekend. It suffers a bit from AM breakthrough and the 2N3904 transistors used in the AF sections are too noisy really. This is really not a perfect radio, more a work in progress.

Why the name? The Pipit was a similar (better!) radio design I put in SPRAT many years back for 15m.
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2 Jul 2008

Micro80 4-transistor transceiver QSO


After some time without use, I resurrected the little Micro80 4 transistor transceiver for 80m last weekend. To increase the power a bit I've now got provision to run it from an external gell cell battery at 12v, so giving me about 2dB more RF out compared with the 9V internal pack. Using it with the bench PSU was impossible because of 50Hz hum pick-up. I also managed to improve the AM breakthrough by around 10dB at least by putting a 4n7 cap across the base-emitter junction of the first stage of the darlington in the RX AF. This makes it a usable radio on 80m at night now as it is not obliterated by the BC stations around 4MHz. Success soon followed with a solid QSO with G3XIZ in Biggleswade around 30 miles away late Sunday afternoon.

24 Jun 2008

Wet square on 6m

Just beat the pile-up to work UT1FG/MM on 6m SSB in IN38 square out in the Atlantic. Obviously I have not worked this square ever before!

501kHz listening

Having re-erected my end-fed wire antenna I am able to listen to 501kHz again. First station heard recently was G3XIZ on CW at 579. I have an NoV to transmit on the band so really must make an effort to get some sort of TX together.

22 Jun 2008

6m DX QSL card from K1TOL


This is the QSL card confirming the June 25th 2007 6m QSO with Lefty, K1TOL. I was using 2.5w ERP at the time to a small vertical! Magic band? You bet!

Lefty has a big 6m antenna farm and runs 1kW, but I much appreciated him hearing my tiny signal and giving me the RST519 report that night. It was one of the best contacts I have ever had in 40 years on the bands.

20 Jun 2008

Real 6m DX at last


Earlier this week 6m bucked up a bit allowing W5OZI in EM00 square to be heard hear at around 8000kms! Also heard were N3DB, 4X4DK and 4Z5LA. This was a few days ago now and I've not heard any further "super" DX since when I have listened. It is amazing what can be heard on just a small vertical antenna fed to the FT817 via about 40 feet of RG58 coax!

Also this week I received the QSL card from K1TOL for our 6m transatlantic QSO last summer - my best ever 6m QSO with just 2.5w ERP.

11 Jun 2008

Canary Is and Cape Verde Is on 6m

6m opened up nicely this evening allowing two QRP SSB contacts into EA8 (EA8YT and EA8CQW) both in IL18 square. Also heard the D4C/B beacon in Cape Verde Is for the first time just hovering at the noise level for me at best.

10 Jun 2008

Still below average on 6m

Just one EA worked on 6m QRP yesterday and still no further transatlantic stations heard. Conditions definitely not up to last season.

5 Jun 2008

6m not as good as 2007?

Do others agree that 6m conditions have not been as good as in the 2007 season so far? This year I've only heard one transatlantic station (HI3TEJ) so far, and he was only just audible. At this point last year I'd heard several Caribbeans and USA/Canada.

1 Jun 2008

Photo of Homebase10 10m antenna


This is a picture of the "Homebase10", a horizontal 10m antenna mounted on its pole above my roof. It is a wire halo which very effectively covers around 600kHz of 10m with a low SWR. It has allowed me to work plenty of stations running QRP with some contacts with just 50mW (see earlier blog post).

Homebase 10 (10m halo antenna)

This antenna is appearing in PW shortly. There is a page about it on my website. http://www.g3xbm.co.uk

26 May 2008

Online SDR

http://websdr.ewi.utwente.nl:8901/ is an online software defined radio which up to 50 people can use at the same time. It covers parts of 80, 40 and 20m and works really well on my little Asus EEE PC. You need both Java and JavaScript enabled for this page to work properly. Unfortunately it does not quite tune down far enough to cover the QRP calling frequencies.

Ukraine worked on 6m QRP

UR5WD in KO20NC was the best QSO on 6m QRP (5w CW on the small vertical) yesterday. He was quite weak with me on CW and I was surprised to work him, but got a 559 report. The band was open most of the day to somewhere in Europe although the opening favoured the east for me.

25 May 2008

50mW 10m QSOs today

WPX CW contest today and 10m in great shape allowing 4 QSOs just now with just 50mW into the recently built Homebase10 wire halo antenna. These stations would have been workable at 5mW or less I believe, but I could not find a larger RF attenuator!

Worked with 50mW: DL7BY (599), DH8BQA (599), DG4R (599), EH3MM (599)

24 May 2008

New 6m country worked

Although not super DX, I worked 9H1 this evening with 5W CW on 6m. The band was in good shape with stations from all over Europe audible and even hints of transatlantic stations (8P9 worked by a CU3 and calling CQ DX Eu).

21 May 2008

6m and 10m lively this afternoon

10m was in good shape at 3-4pm today with plenty of EUs workable including a new country for me on the band in the form of LX1AX who gave me 55. He was running 1kW to a 9el yagi - rather out-doing my QRP and a halo! Still, a new 10m DXCC country is in the log.

6m was also open managing to work IK0FTA with 5W SSB and the vertical.

20 May 2008

Some life on 10m tonight

10m was open earlier this evening to ZD7X. I was unable to hear him when I got on but did work EA and EA6 on QRP SSB.

19 May 2008

Inter-G 10m DXing

Some years ago the RSGB arranged some evening 10m activity periods during a quiet part of the sunspot cycle. It was fascinating to see how far one could work on 10m around the country even with QRP SSB/CW. Contacts from here in East Cambridgeshire regularly extended to as far away as Yorkshire even with just a sloping wire dipole or CB half-wave antenna only. Contacts were often right on the edge and CW helped. I would be happy to try skeds with others in the UK on any mode on 10m although I can only run 10w maximum. I have long thought the 10m band is much under-used for local and semi-local QSOs. It is a pity there is now less 10FM activity around 29.6MHz apart from when the band is open for DX.

Through the ground communications?

Anyone experimented with "through the ground" (earthmode) communications using audio amplifiers and grounded electrodes? I have done this in the past with limited success but never used more than a few watts at 1kHz. These days with ultra-narrowband digital modes like QRSS, PSK31 ad PSK16 coupled with waterfall displays ranges should be quite respectable. My best DX was 0.3kms but I imagine this could be at least doubled using modern DSP techniques. There is some info on this on my website http://www.g3xbm.co.uk

Publicising the blog


Just announced this blog on http://groups.yahoo.com/group/GQRP/ so it will be interesting to see if anyone now reads it.

The simplest possible QRP transceiver?

What do you think is the simplest possible QRP transceiver? The Pixie or Micro80? Have you built a functional transceiver with even fewer parts than these famous QRP radios? If so, post a link. I believe it should be possible to make a transceiver with fewer than 20 parts in total.,

Elecraft K3

Have you seen the new K3 from Elecraft yet? All review comments are very favorable and it is certain to be a hit for those wanting a top of the class rig at a relatively modest outlay for a radio in its class. Although I wouldn't mind one, it is not top of my own shopping list though.

If you have used one of these rigs please let us know how you found it by posting a reply on the blog.

Fredbox 2m AM mini-rig

There have been a few recent posts on the VHFam Yahoo group from people building versions of my Fredbox 2m AM rig. This rig was first designed back in the 1970s and rebuilt a couple of years ago.

Best DX worked was 160kms across the channel to Brittany from South Devon using just a whip antenna - not bad for 10mW. A proposal for a Fredbox 2 is shown in the files section of the VHFam group. This is a DSB version based on the NE/SE602 double balanced mixer.

10m and 6m summer conditions

So far I have been disappointed by this summer's sporadic-E conditions, which have not been as good as last year. OK, it is still early days in the season and things may improve. Traditionally, early June is a good time for super DX across the Atlantic to start.

On 10m I am testing my new Homebase10 antenna. This is a wire halo antenna based loosely on the cobwebb and the GM3VLB antennas. It is called the Homebase 10 as most of the bits can be bought from the local Homebase or B&Q stores.