From the history: VHF CONTESTS 50 years ago
@ OK1AIY
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VHF contests are favorite activities among radio amateurs around the world. They give an opportunity to test improved equipment and antennas from the last year, new operation methods or various new gadgets. Now we live in a „radio-amateur paradise“ time when the hardware and software are available to anyone for purchase. One OK ham described the actual state „Yes, now we finally reached justice: having a good equipment is not an advantage of those who can make it“.
Twenty years after the above sentence was published, the vast change had occurred in technical possibilities but also in thinking of younger generation of hams. It became common to build huge antennas, and by using high-power transmitters or sophisticated devices to achieve many DX QSOs, and good ratings in contests. This is confirmed by contest result tables. It was not so earlier, and I think the young generation should know how a 2-meter contest was like 50 years ago.
Such a view is not quite simple, and I am afraid not well understood by everybody. From our dictionary the concept of understanding, frank admiration and honesty has slowly evaporated. The significance of a hard work, patience and skills has changed a lot.
Many people could find the above not understandable as 50 years is a really long time in a rapidly developing world. Back then there were not too many possibilities to make „progressive designs“.
Viewed by the contemporaries, the time could be seen as a „neolith“, and many designers would laugh at the technology we used. Available components were only those suitable for „consumer electronics“ of a poor quality, (resistors with iron leads that could not be soldered, or yellow ceramic capacitors easily breakable) so we often used German surplus parts if still available.
The knowledge of VHF technology was also poor, we had no experience and gained some over a long gruesome path, step-by-step. In libraries there were some books as VHF laws of propagation were known since 1930s, and A.Weber's book on Very Short Waves of 1957 was quite valuable.
In 1961 a new book appeared, A.Rambousek's Amateur VHF Technology, in which amateur design was well described even for the beginner. I was also lucky that in Vrchlabí where I was an intern in 1950s, were very active HF and VHF amateurs, and the radio club station OK1KVR was very well ahead in contest result tables. Some „strong individuals“ mastered good designs, and one could look over their shoulder to learn. It is worth of mentioning that the TV retranslator for Hořejší Vrchlabí was built by Pavel, OK1GV as well as a copy of Collins KWM-2 transceiver, and a 2-meter transmitter with a tunable coverage of the whole 2-MHz band width. Also a modification of MweC for SSB operation by Jirka, OK1FT, was so unique that it has been used till now.
One issue of Amateur Radio magazine brought a nice description of a 2-meter converter for FuG-16 receiver (German surplus) which was used for my own design (following picture). To make it work I had to build a grid-dip meter (GDO), covering 5 through 300 Mhz which proved itself as an important instrument for basic tests for many following years, or even decades (Figure below).
The first converter had no quartz crystal control, the input cascode was PCC84, the mixer and oscillator, PCF82. In the sixties, evenings on 2 m were quite active, so I could verify every change in the converter. A new better vacuum tube was PCC 88 which the clever guys of TESLA could put on the base of PCC84 used in almost all TV sets. A noisy TV picture was changed into a nice photo after replacing PCC84 by PCC88. The following converter thus had a E88CC input stage, and was crystal-controlled.
The figure above shows the quad antenna, 4 x 10 EL Yagi, one of which was used in the 1961 VHF Contest. In following years we tested it in Field Days and we left the monster on Žalý hill till the September Days of Records. It was not a good idea: nobody stole it and it stood till October through bad meteo conditions, when we dismounted it. The problem happened otherwise: individual antennas were connected by sections of a black twin-line. At the start, the quad functioned extremely well, and proved to be a perfect „weapon“ for the future communications. We, however, forgot about what would happen during a storm on a 1000 meter hill where the monster attracted electric discharges. The copper wire in connecting twin-line was missing and remained as tiny balls on surface . Such feeding lines are no more done this way as we can now use good coaxial cables that can offer also a good mechanical stability.
The following picture shows Walter Schoen, OK1 WR, and Raymond Ježdík, OK1VCW, during the 1955 Field Day on Velka Deštna hill as OK1 KRC, lower the Hurdobus named after Mr.Hrubý, company driver, during the Day of Records 1954, on Klínovec.
The transmitter was desigend in a similar way. The crystal oscillated
at the fundamental frequency, and 24 Mhz was taken out at the plate circuit. The advantage was that also crystals at 4,8 and 12 Mhz could be used. One can be plugged into jacks in the chassis. A schematic was saved till now including the modulator. Back then the modulation was described as „by the clamping tube“ and so tested. Of course it was AM as used in professional radio stations.
Modulation signal drove the G2 of the final-stage pentode. The clamping tube was ECL 84. The modulator allowed to adjust modulation depth by several potentiometers as well as audio level, with a piezo-crystal microphone cartridge available at any local ELEKTRA store. The result was „ringing as a bell“ modulation.
An important component of the systém was the antenna. In the American Hand Book there was a 10 EL Yagi described made of 0.4 mm welding wires, on a beam made of electrician „armored“ pipe. We made such antenna, and without any RF testing (no test setup available) attached to a 6-meter pole. The turning wheel was located out-of the -window. All Yagi antennas were then a novelty. So far we only knew the 5-element Yagis like OK1KRC type. All longer beams were sharper to point, they were also named directional, mostly different from today's common practice.
Without this directivity the communication would not be possible. Even though the radio-amateur public knows well about the antennas, many still believe in magic white sticks and „squares“ under a window. Antenna feeding was a bit complicated. Coaxial cables were not common back then, only a 1 inch PVC cable with a poor sheath, with one-third of it wrapped in textile threads. Such „cable“ was really bad, copper sheath was gradually blackened by some chemical leaking from the outer cover that also cracked. A good option was the flat twin-lead, even perforated for a lower loss, having a loss smaller than a good coaxial cable. Having consulted OK2TU who also was its user, I used the twin lead at home without problems except when it passed through a brick wall.
I adopted also an antenna relay, RP90 enclosed in a thin sheet box (24VDC used), its third contact was used for +280 VDC to transmit.
Some comments to RF power levels used back then. It was typically units to tens of Watts, no problem. Tinkerers discovered that many good vacuum tubes can be used on 2 meters, even some German surplus if available. Even EBL21 could generate several Watts, but TESLA Rožnov was making higher-power tubes: the best was REE30B capable of up to 100 W which was a respectable Day of Records output. It was, however, out of reach to most interested users, so we used smaller tubes. The „noval“ types (9pins in glass) included 6L41 (the best), also EL83 (but not EL803S). It was also dangerous to use „transmitting“tubes without having the license. In practice, a good solution was to use two 6L50 in the final stage. It was a large pentode with a robust socket, and plate on the cap. The availability was fine as they served as the flyback stages in TV receivers TESLA 4000 and 4001 which were being discarded. I never saw a faulty 6L50, a difference from later PL36 or PL500 (504). I have used a 6L41, and the power output was 6Watts.
So I had some equipment but it was too early for me to have my own license, so I cooperated with Ruda, OK1HK. As the contest location we chose Žalý where the electric power connection did not exist for more than 35 years. But legendary Mr Walter Víšek, in charge of the outlook tower, allowed us to use the new wooden chalet free of charge. Our friend who was distributing coal to mountain chalets by Tatra 805 (a 3-ton truck), brought atop the gas power generator, tables and chairs, so we were able to také part in 1961 Day of Records.
The above pictures come from 1954 Day of Records on Klínovec (21 element Yagi by OK1KRC), below from 4-9-1954 Day of Records, on the former outlook tower on Ještěd. At the 144 Mhz rig , OK1VR and OK1WR, who succeeded to make the first OK-HB QSO with HB1VI. In the left corner, OK1UQ worked for the communication service during a harvest for STS Chrastava.
The September contests were then named European VHF Contest 1954, 1955 (EVHFC 1954, 1955)
The OK stations were not taking an „official“ part but were making QSOs along the local Day of Records at the same time (TNX INFO OK1VR).
The September Day of Records in 1961 was lucky to have a nice warm weather, everything ran just fine, and every QSO was a joy. There was not any rush on the band, the QSO count was several tens. OK1VR worked from Sněžka, he used the start frequency of the band and knew it exactly, so we could calibrate our receivers at any time. We never knew if the propagation conditions were somehow better than at other times. All experience was being gained gradually over time.
A nice participant was HB1LE/P who could be heard all the contest time. When he turned his antenna toward us, his signal seemed to be local. We could hear him even when he pointed away from us.
His QTH was Saentis which was unknown to me, only later I learned how important place it was (Figure below).
A meteo station near Saentis existed since 1882. For us an interesting point is that there worked our significant statesman, astronomer and meteorologist, M.R.Štefánik. His records include one climb in May when he came into a snow storm and barely survived. In 1950s there already were TV transmitters, later also laminate buildings so big that under it a rotating short-wave directional antenna was located. A detailed description was published in one CQ-DL issue.
Operations on 2-metr band were such that after calling CQ, stations declared that they listen by tuning from band start upwards or otherwise. Transmitter frequencies were crystal- controlled, some users had several crystals and a switch on the panel. Others simply replugged the crystals.
We have used a a special gadget: accurate crystals for 8.000 Mhz from TESLA Hradec Králové, in a precision mechanical holder.
Replacing the bare crystal took several seconds, while the grinding set on the table allowed swiftly move the frequency from 144.000 Mhz upwards. For grinding a very fine Al2O3 powder (aluminum oxide, called „Vrchlabit“ used to insulate vacuum-tube heaters) was used. Several passes in figure eight on a wetted glass board, cleaning by water and alcohol, and the crystal could be put back in the holder, and oscillated several kHz higher. So we had „pre-ground“ set of crystals, and by them we could move to any needed frequecy on the band.
One of operation problems was interference. It is a wide-scope problem worth of a separate study, and quite complex. It remains a problem for skilled experts with a modern instrumentation.
Back then , I wonder how we did not perceive so much interference with all simple home-made equipment, contrary to what we have now, the suffering in the contests. Although the new transceivers are all „professional“ quality.
In the above pictures, antennas for 2m and 70 cm, designed by OK1VR, used in the 1954 Field Day
on Velká Deštná, under OK1KRC. Below, the transistorized (solid-state) TX and RX for 144 Mhz by OK1AIY. It delivered 10 mW output when powered by three flat batteries, and used from a car.
The picture from 1961 Day of Records is unfortunately missing. Over 50 years there were some dramatic events, and Ruda, OK1HK, could not find it. Maybe he would find it one day.
What more to add?
The beginning of the 60s was marked by the progress in solid-state technology, that affected professional as well as amateur designs. The first „citizens'“ radio station TESLA VKP 050 appeared which allowed two-way communication over 1 km as a handie-talkie model.
Who could expect that once (today) one could freely purchase (and without any ID) such a walkie-talkie in a grocery store (LIDL) next to potatoes, and if it fails due to a poor contact, nobody would care to repair it. Nobody could dream about the future when nice components will be available for reasonable prices, and one would be able to use them to create modern equipment. And often we do not need to buy them in a store: they can be extracted from a discarded equipment in a waste yard.
Many designers, however, refuse to bother by a fine hand work. Time is dear and one can order ready-made function blocks. Everything has been made by someone, what cannot be found at home can be ordered from America or China. Using the phrase that progress cannot be stopped, we come to a joy how we conquered it again. Improvement in quality is seen everywhere. A satellite LNB is full of fine GaAs FETs and nobody cares if it is seen discarded in a waste container.
Before we entered this Eden of dreams, we spent tens of years by hard work. A new equipment was being developed over years, and a successful QSO was only „a cherry on a pie“.
We have had, however, an adventure in creating new stuff, and everybody enjoyed it. It was the best opportunity to learn a lot and the experience was then well used at work. Designers met to solve problems, and friendship appeared, often beyond borders. A collective cooperation lasted for years, and good results brought a joy of a good life.
This paper was also published in print in Practical Eectronics magazine, with
permissione (PE/AR Magazine – Practical Electronic and Amateur Radio, Czech
amateur magazine, in Czech).
Translated by: ing.Jiří Polívka, OK1-5037, Springfield, Missouri, USA
Source of information: OK1AIY
Česká verze