Wednesday, 31 July 2013
Tuesday, 30 July 2013
SB: PNP AF transistor
SC: NPN HF transistor
SD: NPN AF transistor
SG: Gunn devices
SJ: P-channel FET/MOSFET
SK: N-channel FET/MOSFET
SS: Signal diodes
ST: Avalanche diodes
SZ: Zener diodes
Monday, 29 July 2013
The circuit can be used till RF powers of appr. 50 Watts. When measuring larger RF powers with a diode, the max. tension of the diode can be exceeded thus introducing an inaccuracy in the measurement. This disadvantage does not exist when using a rectifier tube. Of course 6.3 Vac must be available for the tube’s filament. A Philips EZ80 or EZ81 should work fine in a similar circuit. The measuring device must be calibrated before it can be used.
Sunday, 28 July 2013
It contains 4 times a NE602 smd ic, 8 opamps LF353, some NE604, xtals and lots of SMD capacitors and resistors. Also coils and an UHF tuner is present. Must have been a pcb from a CATV device I guess.
Anyway, I am glad with all the new components. Removing the SMD capacitors for the prescaler was succesful.
Saturday, 27 July 2013
PI6ZTM received on LNB without dish on my attic roof
Rain is a known attenuator for EM-signals in the GHz range. Apparantly the PI6ZTM signals on 3 cm were not influenced that much. The signal is quite strong at my QTH. Repeater antennas are about 60 meters high on a building "The Blankaard" about 5 km from my QTH. Therefore it is not a real challenge to receive the ATV repeater.
Heavy rainfall above the mid of The Netherlands (including Zoetermeer) this afternoon.
Friday, 26 July 2013
eQSL is an easy and nice method to exchange QSL cards in a digital way. I use it for over 5 years now; no post stamps required. If you are interested have a look at www.eqsl.cc
But of course the paper cards remain the real stuff !
In the end this counter should be able to measure frequencies up to 2 GHz. I am still waiting for the components of the prescaler (The MB506 and 3 7490 dividers). The design of the pre-scaler can be found on my second posting on this blog.
The main design is from India. Have a look here:
Previous year I built the PIC16F628A version and this counter works fine till frequencies of about 50 MHz.
A small ferrite core inside a coil realizes the magnetic loop antenne to be tuned.
No expensive vacuum glass capacitors - which are often used in this type of antennes - are required. The antenna is designed for the 80m band and is constructed in a way that portability is garanteed.
Two fixed value high capacitors (120 pF / 10 kV) are used; this type of capacitors can easily be found and are not expensive.
Richard has used this antenna with SSB RF powers up to 100 Watts and that is a lot for this type of antennas. I would keep great distance from this antenna while using this amount of power. (Magnetic) fieldstrengths are enormous in the near field of this antenna. Take care !
The complete story:
This article was published earlier in the "QRP Nieuwsbrief 132, December 2009"
Thursday, 25 July 2013
The static plates are made of pieces unetched PCB. The variable plates are aluminium. This capacitor works fine in my magnetic loop antenne. I have been able to made some QRP contacts on 80 m with it without the use of a long wire antenna. Still handcontrolled. Remote control would be a nice improvement.
Below you see the antenna configuration of Maarten;
Tuned in on 20 meters and was able to make a short QSO with SV3GLL, Zacharias.
RF power out was 10 Watts into my G5RV junior antenna at 14.150 MHz. Good signals from Greece and of course I was given a solid 599 as well :-)
The MB506 chip can be bought at Kent Electronics in The Netherlands (provence of Zeeland) (euro 6.50) ;
This is my first attempt to create a blog.
I have the intention to enter some interesting information now and then which has any relation with radio communications. Hope to gain some experience with internet blogs and entertain anyone with interest in radio.
Behind dad's 19-set, Culemborg, 1968