We start with contesting - the fourth part

Contesting is mentally and in the case of more than a few hours of racing also physically demanding. Race at full speed, at any time on 100% – search for stations, call challenge, logovať, operate TCVR and other accessories, change strategy,… therefore, we will make it easier.

Improving income in the contest

A serious contestant will definitely be interested in improving their income. The ability to receive quickly and without problems is a key factor for success in the race. This feature can be improved by regular participation in the race but also technically - by using special antennas for reception and improving the characteristics of the receiver. Since almost all commercial transceivers have a receiver designed as a superhet filter method, these are the properties of filters, which significantly affect its properties.

NF filter at the output of the receiver

The cheapest is the addition of an NF filter connected to the output of the receiver. In particular, CW filters are used, whereas the standard MF filters are relatively wide. More expensive NF DSP filters offering more filtering options (LP, HP, BP, notch, NO) they will help especially in specific situations, for example, they help pull a weak signal out of noise.

Effect of MF filters and roofing filter in the receiver

We achieve a better effect with MF filters. It's for a reason, that we will remove interfering signals in the receiver as soon as possible, the more we "lighten" the subsequent stages of the receiver, which then more easily process the desired signal. For this reason, the so-called. roofing filtre.

Quality MF filters are not a cheap affair and it pays to take the time to make the right choice before buying. We are interested in bandwidth for -6dB, pre -60dB (the ratio of these two data is the filter factor determining the slope) a stopband. Crystal filters have better properties than electromechanical filters, however, not all devices are available. In the world of contesting, INRAD brand filters are a term. After installing the filter, do not forget to activate it in the menu, resp. reset some parameters according to the manual.

I am interested in the material about INRAD filters from Milan OK1VWK: www.sweb.cz/ok1vwk

Correct setting in the service menu

Occasionally, this happens when you set up a device, that the user, out of ignorance, sets an item in the menu incorrectly. This applies in particular to changes in the service menu, but even incorrect setting of the DSP filter can lead to the conclusion "it doesn't work". Let me explain when consulting the setting with a more experienced colleague, what which parameter means and how it affects the properties of the device. DK9VZ analyzes can help in selecting the appropriate equipment http://dk9vz.com/rx.htm

Use of preamplifiers

The use of preamplifiers is useful for VHF. The usual noise figures of VHF transceivers are relatively high and by including a preamplifier we have the possibility of a real increase in sensitivity. However, this should not be at the expense of resilience. Therefore, we set the gain of such a preamplifier to only a few decibels. Otherwise, signals at a much higher level will enter the transceiver, which results in an increase in intermodulation products. An example is FT-857/897, whose sensitivity in the 70cm band is significantly increased by connecting a preamplifier.

Final stages – power amplifiers

I recommend using the output stage only by more experienced radio amateurs. It also depends on the performance categories of the race, whether it is important to invest in QRO from a tactical point of view and also from the point of view of a possible TVI. Commercial PAs with bipolar transistors usually have a problem with imperfect bias sources, making them a big problem especially for the surrounding amateur radio. He was on the web some time ago OK2KKW described an excellent source of bias for these PAs.

Very good an alternative to PAs with bipolar transistors are PAs with V-MOS transistors. These FETs work with safe voltages and their properties are much better. For a very interesting price, for example, the 600W kit is offered www.communication-concepts.com (on the web, some VHF PAs are also mixed into HF). After adding a source and low-pass filters, it is possible to implement a powerful PA at an affordable price.

Electronic PAs are popular in our region due to the low price of electronics. The disadvantage is the more complex mechanical construction, the need for tuning when changing the frequency (on KV) and life-threatening voltages. The advantage is the high resistance of PA and decent suppression of harmonic frequencies.

A "reliable source" is also an element, which decides on the comfort of the race. When contesting, the resource is more stressed than in normal operation and therefore we pay attention to it, to prevent the transformer from overheating, diodes or stabilizing transistors. It is good to test the new source before the first race.

Accessories for contesting

The PSV meter / wattmeter is a common measuring device in a ham shack. Unless we use a PA or tuner, we can do with it, which is built into TCVR. This meter has been described in its entirety, and many designs are certainly not accurate. But even such an indicator is better than none - it feels good, that "performance goes outside".

The vast majority of racers prefer listening to headphones, resp. for SSB headsets, headsets. Ergonomics are essential - the headphones must sit firmly on your head, but pleasant. The price is not decisive.

A headset is almost a necessity on SSB. With a handheld microphone, you can only contest if you keep a paper diary. Typing on the keyboard with a microphone in hand is quite impractical. A headset with a microphone also has a beneficial effect on the optimum remodulation, as a constant distance from the mouth is maintained. Headset costs + foot switch + a simple crossover for an electret microphone costs hundreds of crowns. The richer ones can also reach for professional sets, e.g.. Heil.

Electronic keys, elbugy, they serve not only to improve the quality of the transmitted CW signal. Elbug with memory allows you to send predefined texts, e.g.. challenge. If we realize how many times per contest the challenge is sent, The advantage of Elbug is obvious. Advanced keys also allow you to send special texts, for example, an automatically increasing connection number.

There is also a device for automatic transmission capable of transmitting a challenge. They are CQ-feeders, v anličtine digital voice keyer, abbreviated DVK. These are based either on digital audio memory or use a PC with a suitable program.

Use of computer for contesting

The PC has become domesticated in the ham shack of the amateur radio. The computer can act as an elbug, DVK, DX cluster, control the transceiver but above all keep a diary. The DX cluster represents “many ears from all over the world, which provide real-time information on stations in the band ". If the TCVR control is connected from a PC, we can retune with one click and make a station, which you would (perhaps) missed.

Any self-announcements are forbidden during the race (spotting your own brand) v DX clustri. However, such advertising is allowed before the race and even appropriate. Various newsletters and special websites are used for this purpose. In addition, the practice of sked - agreed connections is common. It is mainly used in VHF bands, where, due to the complexity of the connection, it is also practiced to negotiate sked during the race in the form of a chat, e.g.. via ON4KST chat.

Atalanta Locator OK1DUO

It is very popular in our region diary from OK1DUO – Atalanta Locator. It has spread mainly thanks to intelligible language, good stability and, over the years, the creation of an extensive database of brands. You support VHF contests and OK / OM HF contests. Its disadvantage is running in DOS, which brings with it certain problems in the era of more modern operating systems.

N1MM diary

He is a representative of the new generation of newspapers N1MM. It is a very variable log under Windows. It allows connection to the cluster via telnet, can control TCVR, has DVK, bandmapy, detailed statistics, etc.. It supports all major HF and VHF contests, of our contests, only the OK / OM DX Contest is directly supported. Contest Calendar, which is not supported by the user (with good computer skills) to complete. Because of the benefits, which this log has and unified control, I added the OM AC Contest and the SSB League in this way - albeit with minor restrictions.

Other used contest logs

Other used contest logs: Penguin, SD, TACLog, VUSC, WriteLog, VHFCTest4Win.

Glossary

log - log connections
superhet - type of receiver, where the signal is first converted to an intermediate frequency, on which it is easier to filter and amplify, it is then detected and amplified to the headphone or speaker output
NF filter - low frequency filter
MF filter - intermediate frequency filter
DSP filter - digital filter
HP - upper pass,high pass filter - passes signals above the set frequency, suppresses lower frequency signals (high pass)
LP - low pass, low pass filter - passes signals below the set frequency, suppresses signals with a higher frequency (low pass)
BPF - bandpass filter - passes only the signals of the set part of the frequency spectrum (band pass)
Notch - filter suppressing one frequency, e.g.. whistling
NR - noise suppressing filter (noise reduction)
Stopband - maximum attenuation of the filter in the impermeable zone
Intermodulation products - unwanted receiver products - phantom receipts, which result from the action of two or more strong signals
Output stage - amplifier, followed by only the antenna
QRO code, here in terms of a high power designation
TVI - short for TV interference
PSV meter – standing wave ratio meter
Wattmeter - power meter
Elbug - electronic key for telegraphy transmission
DVK - automatic challenge dispenser (digital voice keyer)
Log - used to record connections (brand, reports, exchanged code, etc.)
DX cluster - a database of stations heard on the band in real time
Spotting - sending information to the DX cluster

Next time: which did not fit into other parts – something about traffic