OK2KKW HW CORNER OK1VPZ
As wrote on the previous page, "life is too short for QRP". And this motto is simply true... I am quite sure, that all of us, who still remember 144MHz PAs with OC170 transistors, would agree with me. Without QRO is not possible to manage VHF connections across Alps, MS, EME, FAI & RS QSOs and not only these. Without QRO you can't imagine decent position in contests.
But QRO is not slogan only. It is a lot of qualified work. And a lot of knowledge. Because without knowledge, experience and polite behaviour is not possible QRO transmitter construct and use. If some of this is missing, the result is trouble... And this trouble is not QRO, but all relations, which may related to possible interference. And it can resulted even in problems in human factor failure...
But not only QRO may brings interference. Large area of possible difficulties may related to other circuits as well as on transmitting and receiving side. And sometimes it concerning to design, use and anticipation. For understanding and step by step movement to the better results and solution of interference between contest stations, we want to be focused to these questions, which are related mutually. Of course it is never ending story. And due to that, this page will be always "in the construction".
On the other side, ham radio community will be very curious to your experience. Please send us your message by email, or visit our discussion board.
Our HW Corner page is still under construction and many of our czech articles are not translated yet, unfortunately. Please be patient. If you have an interest to particular article, please let us know. We can arrange priority translation.
HW articles from:
2001
2002
2003
2004
2005
2006
2007
2008
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For translation from Czech use the Google translator please. |
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| 20.1.2010: | Few more words to the 70cm PA instability, observed in FT847 transceiver from time to time |
| 21.12.2009: | OKOBRH - Remembrance of 70cm transvertor construction [1986] |
| 29.11.2009: | Directional coupler made from two semirigids for SWR protection. |
| 25.11.2009: | Power limits of coaxial connectors here. |
| 09.9.2009: | 20.years old OK1VPZ's article focused to contests interference on 144 MHz. |
| 24.4.2009: | Comments and additional circuit in the issue of ALC modification in FT847 here. |
| 24.1.2009: | SWR protection unit for solid state PAs. More in CZ here. |
| 24.4.2008: | RX antenna switch for multibeaming contest operation in 144MHz band here. |
| 24.11.2007: | DC amplifier for powering current measurment of solid state PA here. |
| 24.9.2007: | How it is with BIAS Circuits for Tube PA? More in Czech with EN links here. |
| 31.8.2007: | PEP Wattmeter offset compensation here. |
| 31.8.2007: | Usefull peripheral circuits related to Solid state PA cooling here. |
| 24.6.2007: | FT847 - ALC modification for transmitter splatters suppression here. More in Czech here. |
| 2.5.2007: | Notes to protection of LNA here and to LNA IMD characteristics in Cz here, here, here. |
| 4.4.2007: | Table of resistors value as well as power dissipation for most used RF attenuators. |
| 14.2.2007: | Where you may acquire printed circuit board for our counstruction designs . |
| 10.1.2007: | Simple circuit for control of PA cooling fan here. |
| 30.9.2006 | Old, but well proven PA 432 MHz utilize GI14b tube here. |
| 14.7. 2006: | Construction of equipment for use in VHF Contests without compromises. Is that feasible? More (CZ). |
| 11.1. 2006: | Technical data sheets and service manuals of some YAESU transceivers. |
| 2.12.2005: | Solutions of FT847 70cm PA oscilations. More. |
| 14.11.2005: | Notch filter for local VHF station interference. |
| 24.10.2005: | New, sofisticated bias circuit for high power VHF PAs with bipolar transistors. |
| 5.10.2005: | Neutralization of tube amplifiers for 23cm here. |
| 18.6.2005: | Schematics and data sheets of BMT226 - Allamat 88 transceiver here. |
| 3.6. 2005: | Update of VHF PEP Wattmeter design for contests here. |
| 31.5.2005: | Measurments of transceivers by DF9IC. Note to phase noise value. |
| 18.4.2005: | Design and construction of universal freq. synthesizer for microwave transverters and beacons here. |
| 10.3.2005: | Size of typical coax lines here. |
| 10.3.2005: | How to make a scale for measurment. Try this SW. |
| 24.2.2005: | Design of low pass filter for 432MHz PA. |
| 14.2.2005: | Design of low pass filter for 144MHz PA. |
| 6.2. 2005: | Calculator for design of suitable dividing ratio focused to PLL oscillators for UHF and SHF transvertors. |
| 23.1.2005: | Desing of automatic regulation circuit for cooling and Bias of tube amplifier. |
| 16.1.2005: | Design of HV power supply with starting automatics and current protection. |
| 8.1. 2005: | Time sequencer for instalation into PA - design here. |
| 16.9.2004: | Power supply for second grid of tetrode amplifier here. |
| 26.8.2004: | Nice transistor for 23cm, which can produce > 80 W PEP SSB, by Philips. |
| 26.8.2004: | Schematic of well tried "roger beep" for contest operation - particularly for Yaesu here. |
| 18.6.2004: | Some links to czech and abroad device suppliers here & here. |
| 31.7.2003: | 1W PA on 24 GHz gives you chance for Rainscatter DX. More here, here & here. (TNX DL2AM) |
| 14.4.2003: | Power dividers here. Antenna combiners by LA0BY here. |
| 29.3.2003: | Rellais for RF applications here & here. |
| 28.3.2003: | Realization instructions for low noise amplifiers by YU1AW here. |
| 27.3.2003: | Motorola released new transistor, which can deliver 200 W on 70cm. |
| 26.3.2003: | N2UO design of power hybrid 90° combiner for 23 cm here. |
| 23.12.2002: | Description of R2CW transceiver (3.8MB) here. |
| 30.10.2002: | Useful SW here. |
| 20.10.2002: | Design of transistor LDMOS driver for > 100 W on 144 MHz here. |
| 20.7.2002: | Table - reflected power and SWR relations here. |
| 18.7.2002: | History, schematics and modifications of Czech TXR210 transceiver here. |
| 7.4. 2002: | Design of 23 cm QRO PA by KD5FZX with GS23b tube here. |
| 18.3.2002: | Design of simple circular rotator display here. |
| 10.3.2002: | Simple OK2KKW antenna for 1296 MHz here. |
| 6.2. 2002: | Third part of OK1VPZ interference article here. |
| 4.2. 2002: | Software for antenna design and practical designs here. |
| 28.1.2002: | Input match circuit for PA 144 MHz with 2xGS35b here. |
| 22.1.2002: | Motorola terminated production of many power RF transistors. Data sheets, replacement and info here. |
| 6.1. 2002: | Construction of 21 / 144 MHz transverter here. |
| 22.12.2001: | Second part of OK1VPZ interference article here. |
| 6.12. 2001: | Look into history, where you can read valuable info of OK1DAK to phase noise of oscillators. |
| 5.12. 2001: | Notes of OK1VPZ from 1988 to tube PAs design here. |
| 27.11. 2001: | Old, but still valid article abou sideband noise of VHF transceivers you can find in DUBUS archive here & here. |
| 25.11. 2001: | Copy of VHF solid state PAs from Klínovec 87. |
| 20.11.2001: | First part of OK1VPZ interference article here. |
| 20.11.2001: | HF transceivers performance used for VHF Contests. |
| 20.11.2001: | Copy of correspondence to one interference causa here. |
| 20.11.2001: | OK1DAK article - about IMD of preamplifiers here. |
| 20.11.2001: | MUTEK parts for upgrade of your rig here. |
| 20.11.2001: | Additional filters for improvement of your receiver here. |
| 20.11.2001: | Software of Smith diagram for matching circuitry here. |
| 01.12.1986: | Antenna relay for QRO zde. |