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.

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.

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.

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.

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.

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.

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.

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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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.