The G4JNT 500KHz Beacon

Andy, G4JNT, has produced an interesting writeup of his 500KHz beacon project. This can be found at http://www.g4jnt.com/500kHz_beacon.pdf

Stewart/G3YSX

Web SDR

A number of us are familiar with the webSDR at University of Twente. This is a multi-user SDR that runs on 80m, 40m and 20m. This has now been expanded to a world wide network. This program is a beta test, but the authors say that when these beta tests are successful, the software will be made available publicly on this site. That is very exciting news indeed.

Stewart/G3YSX


PS for a short time only one of the receivers is currently set up for 0..20KHz (it was set up for the Christmas Eve SAQ transmission on 17KHz), so if you have ever wondered what it's like down there, now is a good time to find out.

CARC Shack Familiarisation Wed 23 Dec

A very Merry Christmas to all readers of the CARC blog. As part of the work being conducted in the CARC shack and up on the tower we thought it would be a good idea to keep members up to speed on the changes. Therefore we propose a hands on session in the shack this Wednesday evening.

To start things off we plan to have a introduction for new members or a revision for existing members on the operation of the HF station. We'll be looking at the basics including operation of the FT1000MP, the role of the computer for logging and SteppIR antenna control. We'll also have a segment looking at how to tune the amplifier.

As there are still a few changes that need to be made, this will be a good chance to take on board suggestions for the future.

In the first place we'll concentrate on the simple modes, SSB and CW. In future sessions we'll look at the wide range of data modes which the shack can operate, also the VHF and UHF side of the shack.

I look forward to seeing you all there from 7.30pm onwards.

73
Mike
G0KAD

CARC Oscilloscope Evening Wednesday 26th August

Following on from the success of previous CARC member-participating events, such as the RF power meter, Morse key and receiver evenings it was decided to devote an evening to that great and trusty friend of scientists, electronics engineers and amateur radio enthusiasts, the oscilloscope.

This magical piece of equipment comes in many forms and guises, from simple low budget models costing less than £200 through to high-end top of the range laboratory models, which will set you back thousands. In between of course is a vast range of oscilloscopes to satisfy all types of requirements. These are prices for new equipment. Most amateurs make do with second hand scopes to meet their budget and typical applications.

So what does an oscilloscope actually do? Well, for a start it has a calibrated screen (graticule) or display, (older models used a CRT, modern ones are LCD or LED) on which you can measure frequency, time and shape of a waveform. If it has more than one channel, and four channels are quite common, it will measure a number of waveforms at the same time so that you can for example compare input and output waveforms to and from an amplifier. It is an extremely useful piece of test equipment for signal tracing and faultfinding.

The oscilloscope permits signal voltages to be viewed, usually as a two-dimensional graph of one or more electrical potential differences in the vertical (y) axis plotted as a function of time or of some other voltage in the horizontal (x) axis. Whilst a scope displays voltage on its vertical axis, any other quantity that can be converted to a voltage can also be displayed. Some more advanced scopes are designed as a main frame with space to fit additional modules or sub-units such as RF and AF spectrum analyser.

The scopes on display on the club evening varied in age and specification and included products manufactured by Tektronix, Philips, Fluke, Gould Advance, Hameg, Hewlet Packard and not forgetting a very nice miniature scope designed some years ago for commercial manufacture by Adrian Wood G3VJM.

The evening was well attended, and with plenty of models on display for people to play with, (see photos below), plus some additional boxes such as function generators and signal generators to provide input voltages and waveforms.

John Longhurst G3VLH



Welcome to Ray M0RXJ and Janet 2E0JXR who stopped by for the evening



A nice Tektronics 465B



Adrian G3VJM with a scope that he designed as one of his first jobs as a young engineer



Richard G4ANN and Peter G3LEG checking out a nice storage scope



The Philips PM3240 - a popular scope in its day



Adding a spectrum analyzer to scope makes a useful piece of test equipment

Annual General Meeting Agenda : Wednesday 27th January 2010

Notice is hereby given that the Annual General Meeting of the Crawley Amateur Radio Club will be held on Wednesday 27th January 2010 at 20.00. The meeting will be held in the Clubhouse, Hut 18, Tilgate Forest Recreational Centre, Crawley.

The Agenda for the meeting is as follows:

1. Apologies for Absence

2. To approve the minutes of the Annual General Meeting held on the 30th January 2008.

3. To discuss any Matters Arising.

4. To receive the Chairman’s Report for the year ending 31st December 2008.


5. To receive the Audited Balance Sheet and Accounts for the year ending 31st December 2008, together with the Hon. Treasurer’s Report and to pass a resolution adopting the Accounts.
A copy of the Audited Balance Sheet and Accounts for the year ending 31st December 2008 will be available at the meeting


6. To pass a resolution fixing the subscriptions for the year ending 31st December 2009.

7. To elect for the year ending the 31st December 2009:

1. The Chairman
2. The Vice Chairman
3. The Hon. Secretary
4. The Hon. Treasurer
5. The Hon. Newsletter Editor
6. Up to five Committee Members

8. Any Other Business

BY ORDER of the Committee

Malcolm Harman (G3NZP)
Hon. Secretary

Note : All paid-up members for 2009 are entitled to attend and to vote at the meeting and to nominate Officers and Committee Members.

CARC Visit to the British Vintage Wireless and Television Museum 31 October 2009

On October 31, Club members Stewart (G3YSX), Richard (G4ANN) with XYL Trisha, Malcolm (G3NZP), Brian (G0IOE) and Peter (G4FYY) enjoyed an excellent visit to the home of Gerry Wells, vintage wireless restorer extraordinaire at his home/museum in Dulwich South London. Gerry, now in his 80th year, has been collecting and preserving vintage wireless since the late 1960’s and opened his home as the Museum proper in 1974. Today, the Museum includes vintage television as well as wireless and the intervening years have seen the collection extend beyond the house into purpose built workshops and out buildings at the bottom of his spacious garden.

There is nothing unusual on the outside of the house to hint at extraordinary treasures that lay within. Gerry’s house is one in a large Victorian terrace and the outside appears like any other in the street. The first clue that things might be somewhat different inside came when Gerry opened the front door wearing a white lab coat and we glimpsed for the first time row upon row of wooden wireless cabinets occupying every visible surface in the hall and disappearing into shadows up the stairs. Gerry welcomed us into a large front room where we were surrounded by yet more wireless and early televisions (including the very first television) for a preliminary cup of tea and a chat. This was an opportunity to get to know a little about Gerry’s life-long passion for wireless that began when he was just 4 years old. We learned how Gerry started collecting and repairing old wirelesses that he could not bear to see consigned to the scrap heap. We also learned about Gerry’s commercial success in manufacturing valve audio amplifiers and in vintage wireless restoration. In the latter case, [quote] ”it was like shooting fish in a barrel”.












Throughout this discussion, my attention was drawn to the most enormous audio horn behind Gerry’s chair that, from where I was sitting, appeared to be growing out of the back of Gerry’s head. Seeing our interest, Gerry moved his chair to reveal a very large wind-up gramophone on which he put a ’78. The volume and fidelity surprised us all.

Gerry was born in this house that is now the museum and has lived here all his life. These days his bedroom is on the ground floor for reasons that became apparent when he led us up stairs past more mahogany cabinets on more shelves to more rooms where beds no longer had any fitting place. Shelves upon shelves of wireless lined every wall. The landings also carried their share. Surely, here must be at least one of every type of British wireless ever made. And being the passionate restorer that Gerry is, most if not all were in working condition.












The visit to the workshops in the garden revealed yet another plethora of wireless history. There were rooms of glass cabinets containing hundreds of valves and components. Another room was lined with cabinets of drawers bursting with every spare part imaginable. Some rooms were punctuated with wireless and TV chassis. Yet another room was given over entirely to mains transformers. At one time, Gerry manufactured his own ‘R’ valves in these workshops. Today, one of the larger work areas is a classroom equipped with test benches where invited school children are encouraged to discover the magic of wireless for themselves.

We eventually returned to the house for a final cuppa (courtesy of Trisha who seemed to be able to find her way around any kitchen) and a wind-up discussion on the bygone era of wireless. Thank you Gerry for making the day such an interesting one.

Special thanks to John, G3VLH for organising the day, (and who, in the event, wasn’t able to make the visit) and to Richard G4ANN for transporting us all in his people carrier.

See the Museum’s web site at http://www.bvwm.org.uk for a virtual tour of the museum and comprehensive background information.

Peter G4FYY

HF Antennas, ATU’s and other Homebrew Projects

(What every amateur needs to know on these important subjects) by Bob Burns G3OOU





On 28th October we were delighted to welcome the return of Bob Burns G3OOU. In addition to being an active designer and builder of HF and VHF radio equipment Bob is a retired professional engineer with wide experience in antenna and equipment design, and is an excellent speaker. Bob describes his interest as “Amateur Radio - HF CW Operation, Aerial developments, Heathkit equipment restoration and upgrades. Giving talks on RF Communications topics”. Which brings us neatly to this evening’s event……..


HF Multi-Band Dipole Antenna
Bob started his presentation with a description of his stub-loaded HF band dipole antenna. Experiments had originally started some years back with a classic G5RV and a 10W transmitter, and had rapidly moved on to open wire feeders instead of coaxial cable, with instant improvements in contact rates and signal reports. To address 1.8 MHz matching, loading coils and extra end sections were initially tried with some improvements over the basic G5RV. The original idea for the aerial shown below was found in articles in QEX & CQ magazines and has been further developed for the current location. The length of the top started at 132 feet and has been adjusted to obtain a resonance on 1.84MHz with the stubs in place, and will change with aerial height and location - it is now 125 feet overall. The stubs exhibit an extremely high Q, have little or no effect on bands where they are resonant in odd multiples of a quarter wavelength, and increase the overall electrical length of the aerial on all other bands. A Z-Match or other balanced output ATU is required.

The open wire feeders and the two stubs are made of 16SWG (1/16 inch or 1.6mm diameter) enamelled copper wires spaced 0.90 inch apart with insulators approximately 7 inches apart. The insulators should be UV resistant for maximum length of use in high sunlight locations. The aerial can also be loaded up on 50, 70 and 144MHz with an appropriate ATU (a VHF Z-Match is fairly easy to construct) although more of the radiation occurs from each end than from broadside. All in all, a good multiband aerial.

The original polythene insulators lasted some 5-7 years before becoming brittle from UV exposure. They are being replaced with 8mm diameter acrylic insulators which should last rather longer.

A half size version would work well down to 3.5MHz with an overall length top of 66 feet and stubs of 16 feet 6 inches in length.

Bob then went on to describe the construction of his open wire feeders. These are detailed more fully on his website http://www.qsl.net/g3oou/. The use of such an antenna led naturally on to antenna matching units and here Bob had some interesting ideas, based on the classic Z-Match design. First was to extend the low frequency coverage from 3.5MHz down to 1.8 MHz by switching in an additional inductor below the 80m – 40m coil. The second was the housing of the unit.

Antenna Matching Unit
G3OOU has built a dual Z-Match covering 1.8 - 146MHz in a Heath SB series cabinet with the appropriate metering and switching for multiple transmitters and aerials. Two SWR bridges are used, one for the HF bands and one for VHF. The meter and small knobs are from a Heath SWR Bridge and the front panel has been painted and labeled to match other Heath units.



The VHF section uses a very similar circuit to that of the HF unit although the component values are significantly less, C1 is a single section variable capacitor and HF switch sections S1a and S1b and coils L5 and L6 are not required although S1c and S1d are required. C2 is 35 + 35pF. Note that the minimum value of C1 on VHF should be a few pF so some form of selection may be required and the wiring should be a short as possible. L1 = 2t 1.2inches ID spaced 0.75 inches in total, L2 = 3t 1.0 inch ID spaced 1.0 inch overall. L1 positioned concentrically over L2. L4 = 2t 1.2inches ID spaced 0.75 inches in total, L3 = 3t 1.0 inch ID spaced 1.0 inch overall. L4 positioned concentrically over L3. All coils wound with 16swg enamelled copper wire. The layout of the VHF section is much more critical than the HF section so some adjustments may be required for each constructors own version.

SB-101 and SB-301 Rebuilds and Upgrades
Bob on his website describes one of his passions as “Collecting, updating and rebuilding Heathkit radio communications equipment”. He has several ongoing projects to improve the Heathkit SB-101 transceiver and SB-301 receiver designs to add extra modes and take more account of modern band conditions whilst retaining much of the original architecture. The obvious areas to address included dynamic range, spurious responses, WARC bands, Frequency and Amplitude Modulation, RF and IF selectivity, CW break-in and RIT.

Having used the 7360 beam deflection mixer in an SB-301 rebuild he decided to use those venerable but still very high performance valves as mixers in both the transmit and receive paths and one as a transmit balanced modulator. Bob had brought examples of these projects, which created a lot of interest from the members.

Practical
An interesting feature of most of the equipment Bob brought down was the use (or re-use) of Heathkit cabinets, and Bob doesn’t seem to let an opportunity of acquiring one at junk sales and the like. Newly acquired second hand units have their cabinets washed in the bath to get them clean. Sometimes it being necessary to use a kitchen lemon cleaner and a soft nail brush to remove stubborn grime. Certainly the ones we saw looked new.

Front panel paints are usually Revell or Humbrol - their nearest to "Heathkit green" being No 48. A good primer is required on aluminium. Rub down painted panel with wet and dry paper and flat wooden block.

Front panels of the finished equipment are lettered with dry transfers to give that professional finish. Letraset has restarted the manufacture of dry transfer lettering in white and black. This type of product is also available from Decadry, a Belgian company with UK outlets. Bob not liking gloss finishes on front panels, uses an acrylic clear matt or silk protective spray on top of the lettering.

For new metalwork the chassis aluminium is known as NS4 half hard which cannot be bent as it is too brittle but extremely strong. The G3OOU local supplier is Outlook Stockholders Ltd, Woodcote Grove Farm, Meadow Hill, Coulsdon, CR5 2QQ. Tel: 020 8668 9656. Web URL: http://www.outlookmetalstock.com/ .They can supply a bending grade as well.

Space constrains dictate that this is only a very brief summary of Bob’s presentation and you are urged to visit Bob’s technical site: http://www.qsl.net/g3oou/ for very full details of most of the projects briefly outlined here, circuits of the ATU’s and much, much more besides.

John Longhurst G3VLH

Plans For VHF NFD 2010

Still flushed with the success in VHF 2009 coming first overall in the open section and band leader on 23cm, we must however no rest on our luarels and start planning now for 2010!!

To that end I have produced an outline design for the proposed 23cm antenna which I am cofident will not be beyond the capability of our very talented and resourceful team to construct on site. I attach a photograph therefore of what I had in mind. Go to it Chaps !!

73, de Derek Atter, G3GRO Hon Chairperson.

HOW TOMATO KETCHUP (ALMOST) HELPED RAISE THE Q

During a visit to the Mc Michael Rally in the summer (12th July), my attention was caught by an old and very encrusted tuning capacitor. My cursory interest immediately triggered the words “that’s a pound, mate”, an offer I felt I couldn’t refuse. Then, after the deal was done, “I dunno what you’re going to do with it”. I replied with some quip about keeping a door open, but my impulse buy was inspired by a vision of restoring this fine piece of tank engineering to its former glory and putting it to good use in (yet another) magnetic loop antenna. The weight of the thing suggested it was made from something other than aluminium and since it showed no interest in a magnet, I deduced the construction was brass with some kind of alloy cast end plates.



First attempts.
Carrying this beast around the rally for the rest of the day made my arm ache but became a conversation piece with several sellers. One suggested that the vanes might even be silver-plated. Another suggested that a solution of baking powder might do the trick. However, when I arrived home later that evening, I decided to try Cillit Bang as a first line of attack. The dirt began to lift after about 20 minutes and the letters CYLDON CES.TR.25 became visible on the back plate. Then I tried the hot baking soda bath idea. Not a good move. This left the capacitor coated in a white powdery residue that seemed to seal in the remaining dirt and crud. My gut feel was that this needed something acidic.

Blood Everywhere
At the back of my mind was an idea to try a weak solution of hydrochloric acid (sold as ‘Brick and Patio Cleaner’), but how weak should the solution be? Previous experience showed that a 25% solution of HCl will etch a copper PCB in a matter of seconds. Something less potent was required. Then I remembered that vinegar is good for cleaning lime scale on taps etc. and I reasoned that a clinging vinegar based goo would be even better. There was a very old bottle of tomato ketchup the larder and I eagerly set to work shaking the stuff all over the capacitor, working it well between the vanes with a paint brush. The result resembled a bloody massacre and was very satisfying. I left the great red glob in a plastic bucket with a plastic lid to ferment overnight.

Stage 3 – Cleaning off the bloody mess
I looked into the bucket the following morning with less enthusiasm than the night before and realised that some serious cleaning was going to be required to clean off the abomination of blood clots. So I boiled up a water/vinegar solution in an electric kettle. This is a well-known method for de-scaling kettles and turned out to be a good guise to conceal my real motives from the domestic director. It also gained me a few house work brownie points. The downside was that boiling vinegar made the whole house smell like a chip shop and it was fortunate that I did this while the governor was distracted with other duties. I used 1 litre of Sainsbury’s Basics Vinegar (13p per 500mil bottle!) to 500mils of water and left the capacitor to soak in the hot solution for an hour.

It turns out that tomato ketchup is sticky stuff and great globs of it lodged stubbornly between the vanes in the most inaccessible places in accordance with the laws of Murphy. It took a cloth wrapped around a knife to dislodge the more persistent clumps. I began to feel that perhaps the tomato ketchup idea was not such a good idea after all.

Defeated to Disassembly
Having failed dismally in my attempts to short cut the cleaning process, I finally resorted to disassembling the capacitor down to the last nut and bolt and cleaning each part individually with brass/silver polish. This proved to be laborious task but revealed that the capacitor vanes were indeed silver-plated and that the end plates were probably cast from bronze. The final result of my labours is shown in Figure 2.



Was it a worthwhile exercise? Yes, I think so. The result is a fine, battle worthy split stator variable capacitor that should withstand well over 10kV when tuning a magnetic loop antenna. However, next time I’ll definitely pass on the tomato ketchup.

Peter G4FYY

Report on December 2009 Foundation Liciense Course

I pleased to report that the weekend's Foundation Course went extremely well, but only due to the invaluable support from fellow instructors Brian Gutteridge (2E0MBZ) and Ted MacDonald (G4TTY). Also with nine candidates taking the exam, the job of Invigilator and marking was only made possible with the help of Dick Lupton (M0RXZ).

Thanks also go to Derek (G3GRO) for coming on 20 metres to assist with the HF practical assessments and to Stewart (G3YSX) for helping out with some 2-metre QSOs



Eight students passed, and we welcome Ben Murray as a new member of CARC.

From left to right in the attached photo, names of the successful candidates are as follows:

James Stewart, Anthony Craven, Paul Raine, Nick Vaughan, Ben Murray, Daniel Richman, Steve Pantony and Maureen Comber

73 Malcolm
(G3NZP)

CARC Fish and Chip Supper 2009

On Friday 4th December, CARC again celebrated the forthcoming Christmas with its annual fish and chip supper.

As you can see from the photographs taken by Adrian (G3VJM) a great time was had by all.

Especial thanks go to Richard (G4ANN) and XYL Trish for the repast and to Dick (M0RXZ), Ted (G4TTY) and Malcolm (G3NZP) for getting the club house into a state fit to receive our guests.




































73, a happy Christmas and a healthy and wealthy New Year

Stewart/G3YSX

VK9XX QSO At Last!

Having chased the German VK9XX expedition on Chrismas Island way down in the Indian Ocean several times earlier this week on 40 metres CW with no success using my relatively low windom antenna at the home QTH, I was finally successful last night (25th Nov.) at the CARC Club station at my first opportunity of using the potent set-up with the new StepIR antenna with its 40m folded dipole on the Versatower working the DX station through the pile-up after only the third call. It is always difficult to decide where to park your call within the chasing pack which covers several khz. This time I was lucky and got a reply almost immediately despite not being able to turn the antenna for optimum signal due to a problem with the clamping of the beam to the stub mast thus leaving the antenna pointing approximately eastwards!

73, de Derek G3GRO

Postscript to Activity Report of Tuesday 24th Nov – re: VK9XX

The German expedition station VK9XX on Christmas Island far away in the Indian Ocean has still been putting out consistently good signals into the UK on 40m all this week. Some days as early as 14-00UTC they were audible on SSB at readability 3 and S3 on 7045khz with QRM. Signal strength went up during the day peaking at RST 579/589 on CW by 22-00 UTC accompanied by a huge pack of stations mainly calling HF of them as instructed by the VK operator who was clearly calling “CQ UP”. Unfortunately the operating discipline of far too many of the EU stations was very poor with people often calling directly on the DX station’s frequency rather than several khz HF of them. They were also ignoring the DX operator’s requests for “CQ SA/NA only” – i.e. replies wanted from South America or North America only. I must say that I did not hear any G stations breaking the CW operating etiquette. The operating standard by VK9XX was absolutely first class

The golden rule is always to listen first to find out what is happening before transmitting then use the TX clarifier or second VFO to operate split frequency. It is not always easy to pick out the DX operator’s frequency through the QRM. Tuning gradually LF of the pile-up is one way, the other is calling up reports on the DX cluster via Ham Radio Delux on the internet.

Yesterday during the late afternoon (Tuesday 24^th), VK9XX was down as low as 7001khz right at the band edge but previously he was up around 7009/7010khz. The expedition will be active until December 5^th. . There had been no postings so far today on the DX cluster by

15-00 UTC but take a listen !

73, de Derek Atter , G3GRO

Activity Report – Derek G3GRO

From time to time I have been active on various bands during past month mainly on 80m and 40m but with occasional forays on 14Mhz and 18Mhz and briefly on top band mainly using the 136ft Windom antenna which seems to get out reasonably well despite the fact that it slopes down rapidly to the South away from the house down almost to ground level. I have not yet managed to get the halyard far end hauled up into the 50ft oak tree at the bottom of the garden. The temporary 240ft rectangular loop running mainly on the top of the fence continues to give a good account of itself on 80m on short skip due to its significantly lower noise level during the recent very noisy conditions on that band.

40m has been open to VK during the day sometimes. I heard a VK6 at lunchtime during the Sweepstakes” contest on Sunday 8^th November up at the Club using the new StepIR beam and could also even hear some USA stations very faintly on that band calling CQ “SS” on CW which was surprising during the day on 40m. By mid-evening US stations were by then coming through quite strongly on 40m at home on the Windom antenna and I worked in quick succession N1KF on CW with 589 reports both ways and K1LT with 599 reports.

Later in the week at mid-day on 16^th November I worked an unusual one on 20m in the shape of OX/EA4NA in Greenland again with 599 reports. One however that “got away” later in the evening was W3ZU in Florida heard at 58 on SSB on 7134 khz with a pile up and the best I could manage through the “crud” was a QRZ?

Today (Sunday 22^nd Nov.) again on 40m I heard VK4HFO at 1500 UTC calling CQ on CW at only about RST339 who then worked PC5A giving him RST559. Later at 1745hrs I heard VK9XX on Christmas Island in the Indian Ocean at a solid RST579 for at least 30 minutes working EU stations in a monster pile-up on 7010khz working split frequency. Despite my calling him on 400W many times I did not manage to get through the EU racket spreading over 2 to at least 7khz HF.

Radar History – A Proposed Re-enactment of the Historic “Daventry Experiment

Derek G3GRO reports a recent interesting QSO with Giles G0NXA during an 80m net during which Giles described the existence of a very interesting and ambitious plan to mark the anniversary in 2010 of the historic “Daventry 4roriginally carried out on 26^th of February 1935 by Robert Watson Watt and his technical assistant which in effect marked the birth of the development of radar in the UK which was to play such a vital role in the outcome of World War2.

In the original experiment , the signal from a BBC transmitter at Daventry on HF was used to confirm the presence of an overflying Hayford bomber by detecting reflections from the aircraft thus confirming the basic feasibility of a defence against potential enemy aircraft by a technique which was later to be called RADAR

The proposed modern re-enactment which will take place between 1200hrs and 1400hrs local on 26^th February 2010 will involve a flight of 24 private aircraft at 5 minute intervals flying at an altitude depending on the weather of between 2000ft and 4000ft along the original track followed by the Hayford bomber from Borough Hill to Towcester racecourse in Northants. The availability of the aircraft has been arranged by and will be co-ordinated by Giles G0NXA who is himself a pilot and who has already obtained initial agreement in principle from the local Air Traffic Control centres likely to be involved.

A more detailed formal plan is currently being prepared by Giles. The test signals and ground recording equipment are being provided by two local radio clubs. Information on the proposed test frequency and the clubs involved was not given during the QSO. It is a very ambitious plan and it is to be hoped that it will succeed. No doubt that more information will be available later in the columns of Radcom .

73 de, Derek G3GRO.

Tunnel Diodes

Whilst on a theme of components, Roger G3XBM, pointed GQRP readers to an article by Ramon Vargas Patron called Oscillations and Regenerative Amplification using Negative Resistance Devices. He uses a lambda diode arrangement in place of a tunnel diode. His lambda diode is made from and an MPF102 and a 2N3820. The article shows how these can be used to make a sine wave oscillator and a simple AM receiver.

Stewart/G3YSX

A Primer on PIN diodes

Bob, G3OOU posted an interesting link to the GQRP list a few days ago - a primer on PIN diodes. This was produced by Microsem,i who puchased Unitrode. Unitrode are firm that was very famous for the manufacturer of PIN diodes and who produced a classic reference book on the subject.

If anyone is interested in experimenting with PIN diodes, you can use some types or ordinary power rectifier such as an 1N4007 in PIN diode mode. There is an instructive thread here on the subject which points to an ARRL article by W7ZOI which uses a 1N4007 as an attenuator in the IF amplifier of his spectrum analyser (see fig 5).

Stewart/G3YSX

El Silbo

El Silbo is a fun idea by AA1TJ. It is a voice powered DSB radio transmitter. The audio picked up by the microphone serves both to power and to modulate the transmitter.

Stewart/G3YSX

Silent Key Equipment For Sale

Dear Club Secretary

I have been asked by the widow of Keith G3TLB to try to sell off his amateur radio equipment. Below is a list of available items, in addition there are numerous smaller items and components. I would be grateful if you could distribute this list to your club members and if anybody is interested in anything then they could contact me.

Many thanks

Mr. M. Sheppard
G4FWG
Tel: 01892 652272
Mob: 0790 820 84 84
Email: malcshepp@hotmail.com

Shack contents sale list. 28/08/2009

1. Transceiver TS-870 + speaker and power supply £900 ONO
2. Belcom Linear 2. 144 transceiver £50
3. Trio TM201A 2m Fm mobile £60
4. Kent side paddle non-iambic key £25
5. 8 amp army key £10
6. Repro desk mike astatic £20
7. Welz CT-530 500 watt dummyload £10
8. Heathkit audio generator AG 9U £10
9. VHF/UHF SWR meter. SP-45M 100w £25
10. Farnell sine-square Oscillator LFM4 £30
11. Evershed & Vignoles megger 500v. £10
12. Homemade cap meter £5
13. Micomatch SWR meter £5
14. Sigmasizer 200R 2m FM10 £40
15. Toyo SWR meter 3.5-150 £10
16. Palomar PK44 Electronic Keyer £25
17. 4 position coax switch £45
18. Heathkit Grid dip (mains) £15
19. Fluke 8022A Multimeter £25
20. Wire stripper £3
21. Eddystone Marine Receiver 659/670 £150
22. “ “ “ 730/4 £150
23. “ “ 840A £150
24. IC210 2m Transceiver £40
25. SP430 Speaker £25
26. Heathkit Laboratory Generator RF £25
27. 3 section 60ft Versatower with K2550 auto brake winches and KR400 rotator £800
28. Three element triband Yagi beam £110
    
    

Breakthrough for Code Breakers!

Wih the latest cash injection - half million awarded by the lottery fund - Bletchly Park has finally been recognised for the crucial part it played shortening the second world war by at least two years. This grant will undoubtedly help Bletchley Park become a World Heritage Centre.

Interest in Bletchley has been growing, with nearly 100,000 visitors so far this year.

Carole Souter, from the Heritage Lottery Fund, said: "Bletchley Park is an extraordinary part of the UK's heritage.

"We... recognise the importance of preserving the site as a tribute to the men and women who worked there with quiet and tireless dedication during World War II."Without their dedication, our nation's history might have been a very different one."

Let's hope that we can now stop worrying about the Park's uncertain future and celebrate the fact that, in official circles, folk have finally woken up to the unique importance of this national treasure!

IC92 Display problem - the conclusion

This blog entry is a pointer to the IC92 Display problem article which I updated to show how the story ended.

Stewart/G3YSX

SteppIR and Other CARC Equipment

An afternoon of tinkering and the SteppIR now follows the FT1000 frequency. The antenna needs to be in GENERAL mode for this to happen. While the elements are moving the controller shows a flashing * next to the frequency. When the * disappears the antenna is tuned. It is also necessary to have Ham Radio Deluxe running on the PC as the controller listens to the comms between the PC and the radio. This is the only way of having both connected at the same time.

Please don't use the amp while the elements are in motion. Kind of obvious I know but important.

If you ever get a strange response the SteppIR use the CALIBRATE function in the Setup menu to reset the element lengths.

The rotator is working well. In order to show the correct heading I've just pulled the needle of the controller and pointed it where the antenna points. When we put the VHF/UHF antennas up we'll need to:

a. Turn the rotator so that the HF beam is pointing straight up with the tower luffed.
b. Loosen the SteppIR on the stub mast.
c. Turn the rotator until heading points straight down the hill.
d. Put the VHF/UHF beams on pointing down the hill (towards K2).
e. Clamp a large U-bolt onto the stub mast below the SteppIR.
f. Crank the tower vertical.
g. Climb the tower and spin the SteppIR round to match the other beams and tighten the bolts.

The aim is to get the rotator controller pre-sets working properly which will also allow correct PC control of the rotator once the interface is fitted into the controller.

I've managed to get the full output of the amplifier on all bands from 40 - 10m. The best procedure to achieve this seems to be to:

a. Check that the SteppIR frequency is correct and that tuning has finished.
b. Ensure that the amp is in STBY (disabled).
c. Select RTTY on the radio.
d. Select SWR for the TX meter.
e. Set the RF PWR to minimum (fully counter clockwise).
f. Use MOX to transmit.
g. Increase the power from the radio until the SWR meter begins to function.
h. Ensure a VSWR of less than 2:1 is shown.

Don't use the internal tuner to achieve this and DON'T proceed until the VSWR is lower than 2:1.
The first thing to try is to CALIBRATE the SteppIR from the Setup menu.

If you have a good match barefoot then you can think about bringing the amp online.

a. Ensure that the FT1000 is in receive and that the RF PWR is set to minimum.
b. Check the amp is switched to the correct band.
c. Turn the LOAD dial to around 4.
d. Flick the STBY / OPR switch to OPR.
e. Using the MOX button put the FT1000 into TX.
f. Slowly increase the RF PWR until the amp shows that ANODE current is being drawn (lower LED bar meter).
g. Use the PLATE knob to peak the output power.

N.B. NEVER allow the amp to show more than 3 red bars of negative grid current.

h. Slowly increase the RF PWR knob on the FT1000 until either 3 red LEDs of -ive grid current is shown or the desired output power is achieved.

N.B. You should never need to turn the RF PWR knob beyond the 1 o'clock position.

If you have 3 red LEDs showing and have not yet reached the required output power:

i. Reduce the LOAD setting by a small amount.
j. Retune the PLATE knob.

Repeat i-j until the desired output power is reached. Be careful not to reduce the LOAD too far but just far enough.

I've easily achieved full output power on all bands 40 - 10m.

Have a look at the on-line log. Two QSOs with Indian Ocean DXpeditions on 12m and 17m worked first call.
Pile up, what pile up.

Enjoy the DX.

Tektronix Concepts

So good were their designs, that many years the Tektronix was completely synonymous with oscilloscopes. Every self respecting engineer wanted a Tek scope by their bench and hated being palmed off with a second class substitute. They are still very good popular deigns, though I doubt that they retain absloute the dominance that they once held.

One of the marketing products that Tektronics produced was a series of technical tutorials called Tektronix Concepts, and number of which have been scanned and placed on the web. Even though old, these are very readable documents are worth downloading and reading.

Stewart/G3YSX

At Long Last, SUNSPOTS

So far this year only a handful of sunspots have been observed. Well at long last we have a whole group of sunspots, 32 of the little beauties. Not much effect on propagation yet but this is an excellent development.


Check out the latest images of the sun at the SOHO website and wait for the DX to start rolling in.

For of you who use Firefox as a web-browser search for the PropFire add-on which gives a live status in the lower right of the window.

Fingers crossed
Mike
G0KAD