The latest additions to this site:

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- put together crystal controlled crystal controlled VHF source for phasing measurements (29.12.2013)

- some stuff on the AN/PSM-40 a.k.a. the Systron Donner 5220 Transline Analyzer (28.12.2013):

- checking out potential local 900 MHz UMTS service providers

- test antennas were flat within +- 1dB over the operator bandwidths (22.12.2013)

- rigged a 12 V DC supply for my SPA and drove 450 km around the municipality testing UMTS900 coverage - I was not particularly impressed :-( (23.12.2012)

- highly inhabited areas sometimes had pretty impressive service however (22.12.2013)

- fighting some serious local 144.800 MHz APRS overload using a very sharp notch filter, AO-73 satellite beacon finally undisturbed at the marker (12.12.2013)

- OH9VHF was back in the lab in April 2013 with no output power, this time the culprit was a burned backplane connector (Finnish, 550 kb)

- notes on the connector repair (Finnish, 549 kb, 03.07.2013)

- OH9VHF and OH9SHF got their periodical overhaul (VHF power, SHF power, SHF power verification) (added 18.08.2012)

- addes some experimental Meteor Scatter results from the 2012 Perseids (data from 11-12.08.2012, uploaded 18.08.2012):

- added a drawing of some ideas for optical experiments with the receiver mounted on our ATV repeater remotely controlled camera (04.01.2012)

- finally added some stuff on my Minimalistic Rain Scatter experiments (03.01.2012)

- put together some notes and photographs of the only two R&S HFH Field Strength Receivers in Finland that I am aware of (02.01.2012)

- wanted to tune up up several 22/23 GHz BPF's up to 24048 MHz, so put together an ad hoc test system, starting off with RL tuning and ending up with bandpass optimisation

- the forward coupler is for frequency measurement, the source is a modified Gunn oscillator equipped with LPF and isolator and level is optimized with a variable depth vane attenuator

- the Gunn is AM modulated 100 % at 1 kHz or 10 kHz and it's varactor is swept with a Function Generator ramp signal via HB linearizer, giving a 500 MHz wide sweep

- detection is either linear or 10 dB/div via an HP3581C Selective Voltmeter using a narrow detection BPF. I usually use 1, 10 or even 50 kHz PRF for higher update rate

- here is a block diagram of the 24 GHz Swept Test System made with second hand, junked lab gear and equipment (20.01.2012)

- note the WG attenuators after the Gunn, before the DUT and after the DUT to force tuning to matched loads, IL loss is measured against a digitally calibrated motorized vane attenuator

- a photo of my Mobira DT50 APRS terminal with DK50 printer, closeup of the DT50 terminal and closeup of the DK50 thermal paper printer (08.05.2011)

- since picking up signals from the JAXA Kaguya-Selene Lunar Orbiter, I have been enjoying the NASA LRO signals too, though not with a paper clip any more ;-)

- added some photos of my old (08.01.1990) homebrew spectrum analyser display: analogue display, digital display and a commercial digital analyser for comparison

- settings for the screenshots: 1 MHz/div, 10 dB/div, 20 ms/div, RBW 200 kHz, input level -12 dBm, triggering on video blanking pulse, digital: 600 points/div (!), sample rate 500 kHz

- added some info on my old 3.4 GHz beacon experiment:

- added the block dagram of my 1987 era 10 GHz CW beacon and a photo of the intermediate spectrum at 10 MHz/div, 10 dB/div with 50 mW output (08.05.2011)

- drilled some accurate holes for an RF relay with a simple G-code routine for my Denford Triac CNC Mill: "wood" prototype, "engineering" model and "flight" model

- finally got my 8 m telescopic Geroh 8SPM spindle mast erected, overall photo of mast extended to full hight, view of base plate installation, photo of top section 130 mm interface

- this special mast sports integral run tracks that practically eliminate rotary slack - this solid mast is just perfect for my higher frequency microwave experiments ;-) (26.04.2011)

- here is a web page dedicated to our (the Padasjoki Scientific Research Society) OH3RUD APRS repeater and OH3RUD 70 cm R-NET voice repeater - in Finnish (01.01.2011)

- the very latest additions to my web pages may be found under the link W band (25.03.2011)

- some data on the Hertsien Herruus 2008 frequency measurement competition (20.08.2014)

- recently found this intriguing article on my Grandad's patent, the Fletcher Two-Stroke


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Updated 03.05.2014