Club Call G4HRS Est. 1938
The Journal of
Horsham Amateur Radio Club
April 2021
Sponsored by: Affiliated to:
1 Contents In this issue
3. Notes from the Editor A radio amateur opinion
4. Hush... don’t tell anyone A story about secret codes
8. Rigs anonymous Calculate the quiz answers!
10. Slow pictures A very long weekend of on air entertainment
21. Fast scan A disappearance and a visit to North London
26. Diary of events Full listings for the month
Cover photo: Colossus
Published by Horsham Amateur Radio Club HARCNEWS is produced at home by G4JHI
2 Editorial
This month is a TV special, Slow Scan and Fast Scan! We have the video presentation talk report about Top Secret Cipher held over Zoom, details on what happened over the recent SSTV weekend, a top specialist in making exciting technological items out of cardboard and a quiz to really make you think!
I spend a small amount of time each week doing online surveys as mentioned before in this column. A new survey ‘RAOLS’ (Radio Amateur Operating Listening Survey) has come out in which radio amateurs can take part in. This will include questions about your radio listening and operating habits.
As an example, the survey may include questions such as: How many times do you sneak away in the middle of the night to your shack to look for DX? How many transmitters do you own? What is the feeder length connected to your antenna? What is the colour scheme inside your shack? Do you own a USB cable?
To take part all you need to do is to have read the above by the first Thursday in April 2021 and those selected will receive a link to the survey.
David G4JHI
Copy deadline for emailed items for May edition 20th April - For hand written items the deadline is 12th April.
For items sent by email please send to this address:
N.B. Documents sent for publication may be edited for reasons of spelling, grammar, duplication and occasionally other reasons
Copyright material will not be honoured unless evidence from the author is produced showing permission has been granted for the material to appear
3 March Online Talk: Breaking Hitler's Top Secret Cipher, by Andy G8TJQ, assisted by Phil M0PIT
Andy is a Director and Trustee of the National Museum of Computing (TNMOC) on Bletchley Park and Phil is the Chief Engineer of Colossus.
In WW-II there were about 40 Y-stations which intercepted radio communications and some could direction-find the transmitters. They were critical in giving Bletchley Park something to work on. The HQ was Beaumanor Hall, near Leicester, and the outbuildings there were camouflaged as cottages, barns, stables, chapel and a cricket pavilion. Pneumatic tubes sent messages from building to building to reduce foot traffic which could be spotted by aerial photography.
BP was discovered by a 'shooting party' as somewhere with good communications as roads, rail and a main GPO telephone trunk cable were near. The code-breaking was performed here.
The first target was Enigma messages. Enigma machines had 3 or 4 rotors and were used in the field to send tactical information. The second target was from the Lorenz machine, code-named FISH, and first heard in June 1940.
Code wheel detail
12 wheels from a Lorenz machine
An Undulator machine traced the signals on paper tape called a slip. This machine had 12 rotors and transmitted an RTTY-like signal as 3 tones using Baudot code, which saved radio operators having to manually key in and receive Morse code as with Enigma.
Undulator – Photo Courtesy G8TJQ
4 Only the highest grade traffic was sent via FISH. Strategic traffic was sent to/from Berlin through links such as Vienna to Athens. That link was code-named TUNNY. Other links all had different fishy codenames.
FISH used Vernam encipherment where a key was exclusive-ORd with the text. This was considered impregnable. Luckily for us, an operator on the TUNNY link hand- typed a four-thousand character message on 30th August 1941 and the other end asked for a repeat as they missed some of it. So he reset the rotors on his Lorenz machine and started typing all over again, but he abbreviated some words e.g. 'SPRUCHNUMMER9' to 'SPRUCHNR9'. The net result of that was the second message was 500 characters shorter, thus giving Bill Tutte an insight that enabled him to successfully reverse engineer its design. One interesting aspect of the exclusive-OR function is that some information about the key may be gained by exclusive-ORing the two enciphered messages. Bill Tutte was asked to reverse-engineer the system from these two messages; he sat at his desk for 3 and a half months staring out the window, thinking...
He worked out that it should have the 12 rotors with a different number of possible positions: 43, 47, 51, 53, 59, 37, 61, 41, 31, 29, 26, 23.
The TUNNY machine built at the Post Office Research Station at Dollis Hill was the direct electrical equivalent of the Lorenz allowing the decryption of FISH traffic once the Lorenz wheel start positions were known. This machine used uniselectors and plug boards.
Meanwhile, Max Newman commissioned the design and manufacture of a machine called Heath Robinson which ran two paper tapes in loops, but it was unreliable and the tapes stretched and broke. In spite of that, people could take two or three months to get the rotor settings. This machine could reduce that time to 6 days. As the traffic was strategic, it was still valuable to get into the mind set of the Fuhrer and know of his long-term plans.
Heath Robinson demonstrated that the principle of the machine was sound and that led to the design and building of the Colossus by Tommy Flowers.
Colossus reduced the time to find the Lorenz wheel settings from typically 6 days to 6 hours.
Tommy Flowers, the GPO's senior research engineer, came up with the idea of using valves to emulate one of the paper tapes. 2,500 valves were needed and it was considered by many that they would not be reliable enough. Tommy realised that if the valves were run continuously then there would not be a problem. His machine Colossus was finally working one Sunday in January 1944. It reduced the code- breaking time to 6 hours, and was used in particular to make sure that the real site of the D-Day landings was hidden by deception.
5 Kesselring's machine was taken to England after the Nazi surrender, and now lives near Cheltenham. Captured Lorenz machines were retrieved and taken to England after the Nazi surrender; one is on display in the TUNNY gallery at TNMOC complete with an original operators’ teleprinter and code setting board as used during WWII.
The Lorenz company used to build teletypewriters to U.S. specifications, and must have had a large stock of U.S. threaded screws; they never bothered to switch to Metric!
The Colossus Rebuild Project
A project was started by Tony Sale in 1993 to rebuild Colossus. The machine ran on 6th June 1996. Its optical tape reader ran at 5,000 characters per second, and it had 501 Thyratron valves plus the usual suspects 807, EF36, EF37, 6V6 etc. The Mk2 version was completed in 2007. The gallery was rebuilt in 2014. Obtaining enough valve bases has been a problem and many are custom-made, but the Araldite is showing its age and caused issues.
Valves in Colossus
2007 Cipher Challenge
A plan was made to lend the Lorenz machine to the Heinz Nixdorf Musuem, Paderborn, Germany, and let their amateur radio club send a message which would be intercepted and fed into Colossus for decipherment. There were many obstacles on this: amateurs were not allowed to send encrypted messages, one could not export cypher equipment, insurance was 'difficult' to get when only 4 known machines exist, and sending the 3 tones for mark (900, 1,620 and 2,340Hz) and space (540, 1,260 and 1,980Hz) at 45-50 Baud not easy.
Anyway, these issues were all overcome and on 15th Nov 2007, DL0HNF sent the message out on 80, 40 and 20m. Colossus took four and a half hours to get the wheel start positions. But the winner was Joachim Schueth, who took 59 seconds! He subsequently went to BP to collect has trophy and gave a speech written by his parents. They thanked everybody who worked at BP or was involved in intercepting messages because it ended the war an estimated two years earlier than would otherwise have been the case, and allowed them to get on with their lives in peace.
6 Colossus Maintenance
TNMOC has to pay substantial rent and utility charges to its landlord and can’t afford the electricity bill to run Colossus all the time as in wartime. Two 3.5kW motorised Variacs are used to gradually power up the valves so there is less thermal shock.
There are about eighty 807 valves, and each one resets a bank of Thyratrons. Unfortunately the 807 is subject to a heater to cathode internal short-circuit failure mechanism, and if more than one fails, then spurious resets occur. So the Museum is always keen on supplies of valves in order to keep Colossus in fully-working order.
Thanks to Andy and Phil for giving us an excellent talk. We look forward to being able to have a day out soon and visit both BP and the Museum. For further details: TNMOC website is at https://www.tnmoc.org
G3ZBU
7 HARC Quiz – Does it all add up? Mike, G8CKT
Study the pictures, take a trip down memory lane and then do the arithmetic! (Answers in next month’s HARC News)
A B
C D
E F
G H
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I
A = B = C = D = E =
F = G = H = I =
1. What’s the difference between F and H?
2. Which two radios add up to 1001?
3. Which radio has the biggest number?
4. Which radio has the smallest number?
5. What is (B/C)?
6. What is (I + G)?
9 HARC SSTV Activity Weekend
A report by Mike, G8CKT
Introduction The first-ever HARC Activity Weekend was held on Saturday 27th and Sunday 28th February 2021 and the event was supported by around a dozen HARC Members. A quick skim through the logs submitted by members reveals that the first SSTV QSO took place at 10.21 a.m. on Saturday morning while the last recorded QSO was at 21.57 on Sunday evening.
Participants and frequencies Eleven HARC members were active including: • G3SWC who worked 7 club members and made a total of 22 contacts • G3OGP who worked 6 club members and made a total of 15 contacts • G8CKT who worked 8 club members and made a total of 21 contacts • G4LRP who worked 6 club members and made a total of 15 contacts.
Several of our newer members experienced set-up problems with laptops and computer interfaces but it was really good to have participation from Kevin, G6ZDP, and Steve, M7PWK with some superb bike pictures!
Frequencies used included 3.735MHz (G3OGP, G3SWC, G3ZBU, G3SWP), 14.230MHz (G3OGP, G8CKT, G3SWC, G4EFO, G4LRP), 28.680MHz (G3ZBU, G3SWC, G3OGP, G8CKT, G4LRP), and 144.725MHz (G3OGP, G3SWC, M7PWK, G6ZDP, G4LRP, G4JHI, G3ZBU, G4EFO, G8CKT). M0TWM and G4TPO were both active during the weekend but on a ‘receive only’ basis.
DX
Some DX was heard and worked on 14.230MHz (see Gallery) but band conditions didn’t appear to be very good and several HARC members reported QRM from an SSB contest.
Images
To date, around 100 images and screen shots have been received from HARC members and a representative selection is included here. It’s interesting to note that the choice of images might give you some clues about the personality and state of mind of the originator. For example, plenty of us chose our favourite vehicles (planes, trains, cars etc.) whilst others chose beauty spots, flowers, dogs and cats. What this says about all of you I don’t care to speculate!
Comments
Comments from participants included:
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“It was certainly good fun. Apart from using the new mode, it also got me to blow the dust off my IC7000, get an external sound card for it and fix a heat problem with the IC7000 (fan modification) – so it was a good overall exercise.” Bryn, G3SWC
“We must do another one sometime! I think many are still trying to work it out like me!” David, G4JHI
“I hope others found it interesting and a bit of fun, at least enough to try again sometime, by which time I will be more prepared.” Steve, G4TPO
“What fun!” Alister, G3ZBU
“I thought the weekend went very well, I look forward to the next event.” Jon, M0TWM
“Unbelievable, I can’t get SSTV to work though my laptop on TX but on WSPR I’m being heard in NZ on 40m.” Steve, M7PWK
“I wish these contesters would stop stomping all over the SSTV frequency.” Jon, M0TWM
“Great fun!” Adrian, G4LRP
“Received really good P5 pictures from HARC members on 2, 10 and 80m. In addition, I received pictures from WB9DZS, YV5NR, VE2JCW, W4DIA, VE6KEL M1EMC, WA3TMS, VE3PGT, RA3NO, IS0HGX, WA1QZK, EA7SL, TA1EL, HA8AR. All of these were on 20m with the exception of G4CCC, which was on 2m and 70cm (same signals received on both frequencies), and M1EMC on eighty. Enjoyable weekend” Mick, G4EFO
“Spent much of Saturday afternoon and part of the evening trying to get the setup working with FT- 897D. Therefore, first contact late! Did initially want to join others on 10 metres but could not tune doublet antenna on 28.680 MHz! Added an additional length of 450 ohm ribbon to feeder which resolved the problem but then everyone had left the band!” David, G4JHI
And finally
Finally, a really big thank you to all those who took part and also those who sent in reports, comments, logs and pictures. Hope to see you all next time!
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HARC SSTV Weekend using public web SDRs By Jon M0TWM Introduction Since my own HF aerial is non-operational at the moment, I decided to see if I could receive some of the HARC SSTV images on the various bands using publicly available SDRs.
Software Setup I ran this on my 5 year old (but still reasonably well specified) i7 8GB Windows 10 laptop.
The SDRs that work well for me are: http://topband.ddns.net:8901/original-index.html G8HXT in Hertfordshire – good for 80, 40 and 20m http://farnham-sdr.com/ Farnham WebSDR – good for 2m (and the closest to Horsham)
The SSTV decoding software that I decided to use was YONIQ by JE3HHT. This is an upgraded version of MMSSTV (which doesn’t seem to have been actively worked on for many years).
One problem is that the SDRs send the sound to output devices (like speakers or headphones) whereas the SSTV software expects the sound come from an input device (like a microphone or line in). To solve this I have found the Voicemeeter Banana software (https://vb-audio.com/Voicemeeter/banana.htm) to work very well. This software provides two virtual soundcards – B1 and B2 (also referred to as Voicemeeter VAIO and Voicemeeter AUX). The configuration I use is to set B1 as the default output device (on the Windows 10 status bar speaker icon) and set the input device to B2 (in the YONIQ options input level menu item). Then in the Voicemeeter Banana application I connected B1 to B2. I also connected B1 to A1 to hear the incoming sound through the PCs speakers.
There have been various references to virtual sound cards and audio loopbacks in RadCom including Virtual Audio Cable (VAC), VB-Cable (which is also written by Voicemeeter) but I have found Voicemeeter Banana to be the most useful. I noticed that there is a newer / upgraded version of Banana (strange name I know!) called Potato (equally strange :)) but I haven’t tried that yet. Banana with its two virtual sound cards has proved to be all that I have needed. By the way the approach above is also useful for connecting up to programs like fldigi and wsprx.
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The software running looked like this:
Results On the Saturday afternoon I managed to receive several of the HARC transmissions on 2m and 80m. I didn’t realize that the history got cleared out (when there were too many images or the program was restarted? – I haven’t quite figured that out), so not all the images are here. I also received some images from further afield on 20m. I’ve only included some of them because there were actually quite a lot!
19 Received images:
20 TV Addict
by David G4JHI
Sky channel loss
‘Last December viewers to the Sky platform in the Republic of Ireland discovered some channels missing from the EPG. The reason being that the channels concerned had decided not to obtain an Irish/EU licence post-Brexit and were therefore removed. Sky adds “The stations that are coming off our EPG are not stations that have any significant audience in Ireland.” All the channels concerned were on the Europe wide beam and therefore could be received across that whole region. The good news is that the missing channels can be tuned in manually or a free to air receiver can be used.
364 - Trace Urban 365 - Trace Vault 368 - Now 70s 371 - Now 80s 372 - Now 90s 373 - Clubland TV 509 - CGTN 511 - RT HD 661 - JML Direct 688 - Cruise1st.tv 710 - Aaj Tak 752 - British Muslim 879 - RT SD 891 - CGTN HD
Rail programme
In early 2020 the series Great British Railway Journeys with Michael Portillo was screened on BBC2 and I have finally got round to watching all the episodes that I had recorded. Visits were made to the following places of interest… Orford Ness – used during the war and by the BBC for the World Service
Orford Ness in 1940
21 Transmitter A
Orford Ness in 2019
22 Alexander Palace – the first regular TV service
Live BBC broadcast from Ally Pally in 1936
Opening of first BBC TV broadcast
23 Michael Portillo talks to BBC expert Robert Seatter
Original Ally Pally TV mast beams the signal to 400 TV sets
24 BBC Click recently met Alan O’Donohue an Education Specialist who has constructed a computer museum with all the parts made from cardboard!
Click presenter Spencer Kelly shows a computer keyboard constructed from cardboard
Alan O’Donohue creator of the cardboard museum
25 Diary
Apr 6th, 144MHz FMAC 19:00 - 19:55
144MHz UKAC 20:00 - 22:30
Apr 8th, 50MHz UKAC 20:00 - 22:30
Apr 12th, 80m CW Club Championship 20:00 - 21:30
Apr 13th, 432MHz FMAC 19:00 - 19:55
432MHz UKAC 20:00 - 22:30
Apr 15th, 70MHz UKAC 20:00 - 22:30
Apr 21st, 80m SSB Club Championship 20:00 - 21:30
Apr 29th, 80m Data Club Championship 20:00 - 21:30
For details on the above contests use this link and follow to the appropriate section https://rsgb.org/main/radio-sport/what-is-radio-sport
All above times are BST
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