I tested the R-532 sensitivity, found a ‘vacant’ channel. Vacant, as in no spurs or external disturbances. It shows 236nV for 10dB S+N/N at 30% modulation depth, that’s REALLY good for a 1984 unit 😳
But it coincides well with the last couple days on-air tests, it’s as sensitive as my other receivers.
This is a keeper! 🥰🤩
Look what came my way!! The legendary R-532 Airband receiver, all discrete, no MCU. And it works flawlessly!
Needed a cleanup and a backup battery replacement (luckily no leaks!) but at just EUR 20, this was a total nobrainer. It was manufactured between 1984 and 1987, so they’re really hard to find these days.
Can’t believe my luck here 🤷🏼♂️🤯
Loop antennas are almost unreal… 🤷🏼♂️😂 It seems almost divine that 12 turns on an embroidery hoop and a simple amplifier would let me receive BBC Radio4 on 198kHz hours after sunrise - so much more appropriate to listen to the ‘Sunday Worship’ broadcast 🙏🏼☺️
I’ve always enjoyed listening to 198kHz from my car - it makes me kinda sad they’re planning to discontinue their LW transmissions 😢 LW crosses borders, it works with a simple setup, independent of an internet connection.
Tonight, when the bands open after sunset, I’ll experiment more 🙂🙂
@oz1lqo Hmm - I've got some BF494s :-) Strange bias on the first two transistors - operating current would seem to depend on the HFE (gain) of the transistors but the DC voltages look about right.
From the scope at 1uS/div the frequency for the 25x gain is about 500KHz. How stable is the gain with frequency? I guess, even if it rolls-off, the loop is also becoming a great fraction of a wavelength so that probably compensates a bit ...
The all time classic 555 timer turns 55y this year, originally released by Signetics in 1971.
Lets celebrate by building a classic 555 circuit: the astable multivibrator 🥳🙂
Found a cheap batch of the BLK-89-S+ DC Block from #minicircuits - wondered if they were usable at near-VLF frequencies (they’re specified from 100kHz-8Ghz).
They turned out quite acceptable 👍🏼🙂🙂
I don’t need that many, at all 😂, but it was a bargain and I’ll likely sell some of them once I’m done with the tests.
Amazing you can make an almost flat frequency response that wide 😳 They’re NOS from 2013, but they don’t seem to age, shelf life is ‘eternal’ on these devices ☺️
One of those “it’s you or the dumpster” moments… How could I possibly reject that? 🤷🏼♂️🤭
Søren Kjærsgaard
Giovanni - ZL2GX