From AliExpress I ordered this nice PCB with a logaritmic power detector circuit onboard. The electronics is designed around an AD8307 integrated circuit. The detector should operate in the range 1 - 600 MHz. DC input anywhere between 6 .. 15 Volts.
All ingredients are there to realize a nice S-meter / RF Pwr-meter.
JostyKit was the name of a Danish manufacturer that sold nice Do-It-Yourself kits. One of them was the HF65. In fact a free running oscillator that operated in the FM broadcast band (and below and above J, according to the specification sheet somewhere between 60 -145 MHz). A 2N2219 transistor provided appr. 1 Watt HF. The modulation was a mix of FM and AM, but on a regular FM tuner one could easily hear the HF65 and the sound quality wasn’t even bad.
Anyway around
1977 I played with this nice device and was able to broadcast some music in the
neighbourhood.
I think many liscenced HAM operators nowadays started their radio experience with transmitters similar to the HF65.
T1 = 2N2219
T2 = BC172
Lately there is quite a lot of attention for the 8 m band (40 MHz). Transmissions are done from Ireland, UK and Denmark for example.
This band could be interesting to explore for various reasons:
The 8-meter band shares many characteristics with the neighboring 6-meter band. However, as it
is somewhat lower in frequency it does display the better propagation mechanisms
via the F2 layer normally seen at HF. Also sporadic
E-propagation is common on this band in summer.
After I performed the MARS modification, my FT-450 is able
to receive 40 MHz signals. Of course the FT-450 input filters are not designed
for this frequencies.
I am working on a 8 m bandpass filter / pre-amplifier for the FT-450 to increase the sensitivity for this band.
Hopefully I will be able to tune in into 40.680 MHz - to receive FT-8 signals - soon.
First results;
For more than 10 years I have a piece of hardware in my junkbox that waits for an application:
It is an old school mechanical tuning device, most likely obtained from 'green' radio equipment. The tuning knob drives, tru a variety of gear wheels, a 100 Kohm potentiometer.
The only (German) inscription present says "Funk.stat.18.T"
As a radio amateur I am interested in all sorts of electromagnetic radiation. That includes thermal radiation in the infrared spectrum as well. Lately prof. William Harper visited The Netherlands with a remarkable presentation on climate. I was intrigued by one of his graphs:
Yesterday I found a pretty nice old school mechanical typewriter in the second hand stuff store ("Kringloopwinkel"). It is a Royal KMM 'workhorse' typewriter. KMM stands for Key Set Tabulator, Magic Margin, Machine. Its original design dates back to 1939, pre WWII.
It is produced in 1947 by the company Royal, which had its headquarters in New York City and its factory in Hartford, Connecticut (USA). I found that millions of this typewriter had been produced and have been spread all over the world.
The one I bought shows severe marks of use, but a first trial indicates that most functions are still in tact.
I know this device does not need a battery and has nothing to do with radio. Sometimes I just like old mechanical stuff. But hee, doesn't the QWERTY keyboard look familiair to our PC keyboards ? (Yes, it does !).
On YT, I found a nice movie from Joe Van Cleave who explains the typewriter functions in a clear way:
https://www.youtube.com/watch?v=pjn-XG_WgMQ
Anyway, I will be busy coming weeks trying to restore this incredible machine as much as possible in its original state (where can I buy the ink ribbon ??)
