OK1RR DX & Contesting Page

Ham Radio web site dedicated to CW DX operating and contesting

OK1RR DX & Contesting Page

is being transferred to a new, more modern platform, which will allow easier orientation and improve the clarity of the website. All articles and sections will be gradually transferred, including catalogs, online calculators and other elements that were available on the old website. Visit this site soon, you won’t be disappointed!
Aliexpress - beware!

An open letter to Aliexpress

Aliexpress - beware!Chinese traders have the worst reputation in the world. One trader is able to sell shoes, garden furniture and special electronics at the same time and does not understand any of it. His goal is to earn at all costs and does not shy away from robbing the customer in any way. Brands are often counterfeited, inappropriate, simplified technologies are used, and the use of inferior components and materials is common. The trader is not interested in the value of the product, the product is only taken as a means to make a profit. The Chinese trader does not respect or know European trade rules, apparently unable to understand that a European is not interested in cheaper goods if it means lower quality. If an European wants to save, he will reach for a simpler model with fewer options, but only if even the simpler model meets the basic requirements for functionality and is made of quality components. The rule "we are not rich enough to afford cheap things" always applies.

Differential current sensor

A differential RF current sensor

A small dual loop antenna, in other words a differential RF current sensor is shown on the picture below. (Credits go to Chavdar Levkov, LZ1AQ) Another image shows my implementation – a compact version, made from PCB with conductors on both sides ’embroidered’ with vias. Gerber data available (download here). (as output connector use an

Welcome to FT-SHMATE!

A Modest Proposal
By Victor Rosenthal, 4X6GP


While waiting for VP6R to operate CW instead of FT-8 on 20 or 15 meters during the very short openings to the Middle East, I began to think that FT-8 might not be as bad as I’d believed. My thoughts turned to ways that it could be improved. And suddenly I got an idea that I think will revolutionize digital mode operation, amateur radio in general, and maybe even pay for my beer.

Stop using FT-8

FT-8 is so much less labour and operator skill-intensive than CW/SSB that it has a fatal attraction for DXpeditions – more people can be worked more easily and more quickly. Added to this, “He who holds the gold makes the rules” and DXpeditions mostly hold the gold as we want to work them. So if

Amendment to ARRL DXCC Rules Will Expand DXCC List

The ARRL Board of Directors approved a motion to amend the DXCC Rules, when it met January 19-20. Section II, Subsection 1 of the DXCC Rules now will include a new Subsection (d): The entity has a separate IARU member society and is included on the US State Department Independent States in the World. In

Slovak (OM) prefixes and county codes

Prefix County County code OM1 Bratislava I BAA Bratislava II BAB Bratislava III BAC Bratislava IV BAD Bratislava V BAE Malacky MAL Pezinok PEZ Senec SEN   OM2 Trnava TRN Dunajská Streda DST Galanta GAL Hlohovec HLO Piešťany PIE Senica SEA Skalica SKA   OM3 old calls from Czechoslovakia, prefix moved from OK3 => OM3

Audio transformers 600:600 ohms on eBay

Small, cheap and widely available chinese transformers are frequently used in digimode interfaces, however the documentation is very poor. Both primary and secondary consists of 800 turns of enameled 0.06 mm copper wire wound with double wire. It has DC resistance of 135 ohms +/- 20% and inductance of 290 mH +/- 20%, wound on

The TinyKeyer

The TinyKeyer

the (possibly) World's Smallest Fully-Featured CW Keyer with Computer Support



This keyer, based on Arduino design, employs the famous K3NG code. It can be used with any Windows/Linux/Mac logging or contesting software with Winkeyer USB (K1EL) support. The credit & big kudos goes to Anthony Good (Goody), K3NG, who did the tremendous work. It is a very small unit (outer dimensions 45 x 45 x 18.6 mm, appx. 1.8 x 1.8 x 0.73 in) which does not have any fancy options (a zillion of buttons, psychedelic flashing LED lights or cockatoo colored displays). It is intended for regular CW work and contesting with computer support, most of functions should be adjusted and operated via the computer. For standalone work an acoustic menu in command mode is used. Otherwise, only speed control knob and a mini LED indicating the command mode is on the front panel, nothing more.