6m (4m?) distraction

OK, I'm about 40 years out of date with my technology, so if I live to be 100 you may just find me getting excited by SDRs and the like when the rest of you are busy with thought and matter transfer. Who cares, it keeps me happy and doesn't cost a lot :-)

This last week I have had a spurt of creative (?) energy and have been building. Firstly I started work on the 10m DSB rig. The RX is fully working using the Neophyte as a basis. Next I tried the 14.3MHz ceramic resonator-doubler idea for the LO but was disappointed that I couldn't get it to reliably pull down to a useful part of the 10m SSB band. The plan was to look at a mixer-VFO and then put the whole breadboard together with the DSB TX. But I got distracted....

Instead, I built a simple super-regen AM RX for 6m (or 4m), which works well using T37-6 toroids. All that I need to do is arrange for the RX tuning across the chosen band with a varicap. Next I built a simple series modulator (even simpler than the Fredbox one) and now I've started on a very simple AM TX strip and small linear. The idea is to do a Heathkit Lunchbox "Sixer" AM transceiver replacement but in a very simple solid state and no-IC design. The design is likely to produce around 100mW of AM and can be completed for either 6m or 4m. I haven't decided which yet.

There is not a lot of AM on 6m, but a bit in pockets on 70.26MHz. I know 100mW is not much. But, this is a project I've just wanted to do for years and you'll have to bear with me. When this is done I'll get back to the serious stuff - the proper DSB transceiver that is!

Colpitts VFO parts value calculator

PY2OHH is a very creative ham with an excellent website full of good circuit ideas. I noticed a neat Colpitts VFO calculator there today. You put in the frequency range needed and the variable capacitor range available and out pop all the capacitor values in the tank circuit.

Since including this link the original site has removed the schematic.

10m RX using 14.3MHz ceramic resonator

Tried using a 14.3MHz ceramic resonator (in a x2 oscillator circuit selecting x2 at the collector) with the Neophyte derived 10m RX today. Applied the external oscillator to pin 6 of the NE602 and used the on-chip LO as a buffer.

With a 60pF variable capacitor I could pull the oscillator from 28.563-28.641MHz i.e. about 80kHz shift. Adding some inductance in series with the resonator allowed it to pull lower, but I could not make the circuit work reliably with too much inductance. Conclusion so far is that with a ceramic resonator at a better frequency (e.g. 14.23 or 14.24MHz) this would make a neat 10m SSB RX with the Neophyte. A small amount of series inductance would allow around 100kHz shift around the main SSB part of the band.

Next I'm going to try the mixer-VFO using a 32MHz xtal and a 3.58MHz ceramic resonator. This should cover around 28.40 - 28.46 I think.

10m Neophyte RX

Today I breadboarded a 10m version of the Neophyte direct conversion RX from a 1988 QST. The Neophyte uses an NE602 as the RF amp, LO and mixer and with the output fed differentially into an LM386 audio amp. In my version I used a single toroid 10m tuned circuit and a free running LC oscillator using the oscillator onboard the NE602. As it was a lash-up, frequency stability was a bit average, but it had good sensitivity and allowed plenty of Europeans to be copied on 10m CW and SSB. I used an 8 ohm LS and there was plenty of audio. Overall I was impressed that something this simple worked so well.

Tomorrow I want to try the same circuit but using an external VFO using a VXOed 14.3MHz ceramic resonator in an oscillator/doubler. I am hoping that the resonator will pull well over 100kHz so that it covers a useful part of the 10m SSB band. The same LO will be used for the DSB transmitter assuming it pulls OK and is sufficiently frequency stable.

Ceramic resonator VFOs

David W Searle ZL3DWS sent me a very useful link about the use of ceramic resonators in VFOs. These can be pulled more than crystals but the pulled stability is still better than a VFO. I am trying to use these in a mixer-VFO for my 10m DSB rig. See the webpage by Jack Ponton GM0RWU at the address below. I think taking the output differentially from a tuned circuit across the output pins of the NE602 would be better with a simple link winding down to 50 ohms. http://eweb.chemeng.ed.ac.uk/jack/radio/projects/resnote3.html .

A crystal set transceiver?

JF1OZL has some fascinating ideas on his inspiring website. Typical of his wacky ideas is his 20uW TX for 7MHz powered only by the human voice bellowing into a mic. I wonder if a crystal set transceiver is possible using either the rectified human voice (as per JF1OZL) or rectified received RF to power a micropower TX working alongside the crystal set RX? Even a 0.5uW TX could cover miles on VHF line of sight with a beam and generating this sort of power should be possible through rectification of MW and lower HF broadcast stations.

Japan worked from Europe on 6m

Right on schedule the path across the pole from Europe to Japan has opened up on 6m again this late spring, at least for well equipped high powered 6m operators. The distances are amazing (around 10,000kms) yet this path opens up most (every?) year at this time. Whether or not this is really multi-hop Es is very debatable. Once again it proves there is still much we do not understand about HF/VHF propagation. Amateur radio is continuing to add to scientific knowledge.

Now, wouldn't I like to work JA on 6m with my vertical and a few watts!

10m (and 15m) DSB rig ideas

The GQRP club sell xtals for 24.906MHz for £2 each. They also sell 3.58 and 3.68MHz ceramic resonators at 50p each. Now, mix 24.906 with either 3.58 o 3.68 with an NE/SE602 and you end up with a stable and simple mixer-VFO (when the ceramic resonator is pulled in a VXO) covering two very useful parts of the 10m SSB band or the 15m SSB band. All it needs is a filter on the output to select 10m or 15m injection. I have ordered the xtals and ceramic resonators and will start on the mixer-VFO when the parts come.

My idea is to use the VFO with a simple DSB TX and DC receiver. Such an arrangement will give a simple 10m (or 15m) DSB transceiver covering very useful parts of either band, but with few parts.

Antennas for 6m DXing?

Dave ON8WW sent me an email asking me about what antenna to use for 6m DXing. I replied saying that all I had on the band was a triband vertical colinear (the Diamond V2000) but this has allowed me to work over 50 countries on the band with QRP SSB/CW (best DX >5000kms). It is mounted just above the guttering at about 7m above ground level.

6m is an odd band in that there is not a lot of local SSB traffic (I think) and when the band does open up for either Es or F2 propagation the polarisation probably doesn't matter. Certainly I am able to work (at least) as much DX with the vertical on 6m as I used to work with a rotatable horizontal dipole. The antenna works very well for local (and DX) QSOs on 6m, 2m and 70cms FM of course.

OK, if you want to work marginal propagation modes (e.g. MS using JT6m) or tropo DX then a beam would help. But, if you are prepared to go DX hunting when the band is open, then I think a simple vertical is all you need.

10m/6m Sporadic-E update

It usually happens about now: after the first few weeks of frantic Es activity on 10m and 6m working around Europe (after months of silence), activity starts to drop off. The band is open to somewhere but people are less interested in working you unless you are a new country.

The next excitement is looking for more distant Es openings - into the Middle East, North & South America and the Caribbean. So far this year I've yet to hear a transatlantic opening on either 10m or 6m, but it is still quite early, so I remain hopeful.

Monitoring Monthly - gone

Monitoring Monthly, the UK magazine catering for SWLs and scanner enthusiasts, ceased publication last month with May 09 being the last edition. Their website is still in place for electronic copies to be retrieved.

One wonders, in current market conditions, how well (or not) some of the other ham radio and SWL magazines and ham equipment traders are managing. Anyone know?

LA1TPA - a fellow QRPer

Just got this nice email from a fellow QRPer, Mads LA1TPA, from Norway. Mads, I hope to work you soon on HF or 6m QRP. In this part of the UK there are no mountains to climb with the highest being less than 150m! There are a lot more in the rest of the UK though and I think SOTA is a great idea.

Hello Roger
My name is Mads and I'm a Norwegian QRPer. I'm writing you to tell you that I really enjoy reading your Ham Radio Blog. I got my licence in 2005 and my main interests are Summits On The Air activations and QRP DXCC hunting. I also write a QRP Blog myself: http://la1tpa-qrp.blogspot.com/. I'm a G-QRP member and attended the Rishworth convention last year and also intend to go there this year. Hope to work you 2-way QRP one day.

72
Mads LA1TPA

6m PSK31

Just heard CT1ESJ working an ON station on 6m PSK31. Not thought of using this mode on 6m, but it could be pretty useful for working DX on the band. Certainly the PSK31 area around 50.250 was quite quiet.

Incidentally, I was using Pocket-Digi on my Dell Axim PDA to do the decoding just picking up the signal from the loudspeaker.

7X, EA8 and CT3 on 10m QRP SSB

Sporadic E was good today on 10m allowing QRP SSB QSOs with 7X4AN, EA8CEQ and CT3FQ with the halo antenna. 32 countries worked so far on 10m QRP this year, although there are quite a few "easy" countries still missing, so the total should climb somewhat further before the summer ends. By the autumn the sunspot count should be climbing, so we may get some transatlantic F2 layer propagation this year.

10m very short skip

Just worked EI7JN in Dublin on 10m SSB. He gave me a 59 report. When the skip is this short on 10m it usually suggests the Es MUF is getting very high, so expect 2m to open shortly if not already open for Es DX.

ZB2FK on 10m and 6m

In the course of a week I've managed to work ZB2FK on both 10m and 6m QRP. No great distance, but I don't recall working Gibraltar before, apart from ZB2VHF on 4m when I was at Liverpool University (G3OUL) in the late 1960s when running 4W AM!

DSB transceiver circuits - 10m and 6m

Michele IZ8JJI has just sent me a link to a neat, very simple, DSB transceiver suitable for either 10m or 6m. It is from a Japanese magazine (CQ?). See http://www.cqpub.co.jp/hanbai/books/15/15061/15061_p.180-181.pdf

I am not sure of the power (milliwatts I think) but WHAT a neat circuit!

Working REAL 10m DX at last!!

After calling for 15 mins I eventually worked LU1HF on 28.010MHz CW this evening by F2 or TEP. He had been calling CQ for over 15 minutes without getting a reply and then he heard my 10W to the wire halo and gave me 599. OK it was a contest exchange, so probably much weaker. I think my antenna must have quite a low angle take-off as working this station, against the rest of the world's competition, shows.This is my best 10m DX for some time at 11077kms. So who needs sunspots (the count was zero today).

A few minutes later I worked ZW5B in Brazil who got my callsign but he then lost me.

At 2138z I worked UU7J in the WPX contest.

6m Lunchbox - further thoughts

Further thoughts on the G3XBM answer to the Benton Harbor Lunchbox for 6m. Maybe it would be better to make the rig DSB instead of AM? The design is almost as easy and a VXO crystal at 25.08 or close would give some 50kHz VXO range (50.15-50.20) in a useful part of the band. Also, it would be more efficient than AM. In sporadic-E openings it would produce some DX contacts too if the power out was around 0.5 to 1W pep.

Cyprus on 10m

WPX CW contest and 10m CW quite lively. Just worked C4I (Cyprus) at 599 with QRP no problem.

6m DX to the Congo

I overheard G4DEZ telling another station that he had worked the Congo on 6m CW today. This is some distance on 6m Es! G4DEZ does have an impressive station and antenna farm but this was with 100W, so no super QRO.

6m Fredbox ideas

Looking at project ideas, I am beginning to think about a simple 6m AM transceiver design. The starting point would be my Fredbox design for 2m AM from many years ago. An outline spec would be: 500mW AM crystal controlled TX, simple superregen RX, built as a small modern day "Heathkit Lunchbox" style rig with an RX tuning knob and LS. Such a simple radio would be an ideal local ragchewing radio and would give coverage up to 10-15 miles with a simple vertical colinear antenna, dipole or halo.

A very good example of a 6m superregen (also regen) RX by N1TEV can be found at http://www.arrl.org/tis/info/pdf/9712039.pdf although this is more complex than I would plan to use.

6m QRPP

Worked M0BXT tonight on 6m AM when Andrew was using a single transistor TX using a carbon mic to produce AM! His signal was RS58 with me at 2 miles range but modulation depth only about 5-10%. Still, it was a QSO.

Good Es tonight

Worked ZB2FK this evening at 2126z on 50.090MHz CW. I think this is a new country for me on the band. 10m was also in good shape with lots of very strong Es DX coming through from Europe and N.Africa.

Microvert antenna

Many people are looking for that magic antenna that takes very little space and performs very well on HF bands. Some examples of this claim include the cross-field antenna, the EH antenna and the Miracle Whip. Now all of these have their place. I have used a Miracle Whip and it behaves as one would expect i.e. several S points down on a full sized antenna, but it communicates. Even decent DX has been worked with one (11000kms on 5W SSB) during the high sunspot years.

This week my attention has been drawn to the Microvert Antenna (see picture of an example). Is this a more realistic attempt at an efficient, small sized HF antenna? This antenna was developed by DL7PE. The radiator for 7MHz is only 1.33 metres long and the counterpoise is 8.2 metres. the 28MHz version is very small indeed. Perhaps this is worth a try? See also the Microvert Yahoo Group.

Multi-hop Es or Es+F2?

Last night, around 2100z, 10m was open to South America by what I assume was multi-hop sporadic-E or possibly Es linked to F2 at lower latitudes. There was strong Es to Spain/Portugal at the time so the latter may be more probable. Stations heard but not worked included YP4DYP, YV5EAH and YV4DYJ all on SSB. Distance is around 8000kms - which is some distance for Es alone.

A QRPer's brain

Yesterday I went to get my brain MRI scanned as part of a Cambridge University research project on speech and language. The result is attached. I spent nearly 90 minutes being scanned whilst listening to various sentences.

Someone suggested the missing top part of the brain explains why I am a QRPer!

6m Es

A good opening on 6m his evening with lots of 59+ signals from southern Spain and Portugal coming through. There are supposed to be some CN8 and EA8 stations on too but not heard or worked any yet.

Some Es statistics (2008)

Check out http://www.vhfdx.net/states2008.html which has some fascinating data about the extent of Es openings in Europe in the 2008 season. At times, the MUF for Es reached 250MHz. The VHF.net has a great deal of other useful data and is well worth a regular visit.

Several stations worked by Es today - LA5AKA, SM4EXP, I0KNQ and YO2QC.

Increasing sunspot activity

Sunspot number running at 18 today, a value not seen in a LONG time and solar flux in the mid 70s. Even HF conditions shown as "fair" instead of "poor". Yet more signs we are, at last, coming out of the bottom of the cycle.

GMs on 10m (Es)

Two nice 10m QSOs today with 10W SSB and halo: GM8LFB and GM4JYB (in IO88HP). Usually I have to wait until later in the summer to work GMs on 10m. I was very happy when GM4JYB found me first in a minor pileup! At times the GMs were 59+20dB and would have been audible with 100mW, or even less, given a clear frequency.

DXing - realtime maps

This is a useful resource from VHFDX.net to track openings on 10m and upwards into the VHF bands. A mapping system that plots recently reported QSOs. Thanks to G4ILO for pointing this out to me.

See http://www.vhfdx.net/spots/map.php

Poor Es so far?

Is it just me or is this Es season well below par so far? Very little heard on 6m so far and even on 10m the openings have been short and signal strengths not exceptional. Most stations I hear I can work, even with my wire halo and 5-10W, but there don't seem to be that many on! Tonight for example, 2 EAs and 1 CT1 heard and worked, but that's all. Later I worked SM3EAE with 5W CW.

10m F2 DX

Well, last night 10m opened up a bit with PY2WAS in Sao Paulo, Brazil coming through weakly around teatime. At this time of year there are sometimes North-South openings in which part of the path is assisted by sporadic-E for the first "hop" linking then with F2 propagation further south. Last night's opening may have had a bit of this, but there was little spor-E about and that was all weakish. Earlier there was an OH8 station audible from Oulu in northern Finland and I swear he sounded auroral.

Scout Regen RX kit

Hendrick's QRP Kits in the USA have just introduced a nice little regen receiver kit for beginners and more experienced hams and SWLs. The Scout is a simple 2 band regenerative receiver covering from 3.5 -11MHz. It is based on the classic design by Charles Kitchin published in QST some years ago. It is to be launched at Dayton and on sale from May 12th.

See http://www.qrpkits.com/scoutregen.html for more details.

New (lower) sunspot peak predicted

NOAA has just a few minutes ago (1600z May 8th) released a new sunspot prediction with a peak of just 90 and much later than forecast before (now in 2013).

See http://www.swpc.noaa.gov/SolarCycle/

Maybe I'll have to give 10GHz rainscatter a go after all...

Grandson time

We have two grandchildren. One came to stay with us for the last week and this is a shot of him and I in our garden. If I recall, we were discussing something really deep and serious like the bird that had just landed on the bird table! Both grandchildren bring us such joy and being a granddad is such a wonderful thing.

DXing has to take a back seat when he is with us, but who cares too much? Now our grandson has gone back to his home, I am a little more active on 10m and 6m again.

Stations worked on 10m QRP

Pavel, UR5WCQ was a good signal, but alone, on 10m SSB at 1323z and was worked giving me a report of RS53-55.

Earlier, EA5ON/M was on 10m calling a W4 station across the pond, but I could not hear the W4.

Tuesday May 5th and nice QSO with Andy SQ9MEE in the log on 10m SSB

More sporadic-E now

This evening at 1800z I turned on the 10m rig and heard EA3BOX booming in on 28.487MHz SSB. A quick call and back came a 58 to 59+ report. Yesterday I heard SM3NQM on 6m SSB, so the season has clearly started now.

10m open (spor-E)

II0DIVA (special call) coming through on 10m SSB this evening. This is the first sporadic-E heard this season. Later, at 1910z, I worked IY7GM, another special call, with a 59 report received using the IC703 and the wire Homebase-10 halo. He was 58 with me.