When switching off my radio gear yesterday evening I was suprised to find a part of an FT-8 qso from India (QTH loc. JQ05) on my screen ! These were certainly the most distant 50 MHz ham radio signals I ever received:
QSO between VN4VUP and 8U8MBJ on the FT-8 screen.
What kind of propagation must this have been ? Multihop sporadic-E ?
With a rather simple circuit I was able to restore a Yaesu Power Supply Unit FP-4. The PSU is almost 40 years old and the internal original circuitry was damaged. The transformer, diode bridge and 6800 uF capacitor were still ok.
I found this circuit to replace the existing electronics:
Soldered this small circuit on a vero board and installed it in the housing:
Now the FP-4 PSU is up and running:
Note: PNP Power Transistor MJ2955 may be replaced by MJE2955, TIP2955 or 2N2955.
It is capable of delivering appr. 20 Watts RF at 70 cm. The module uses a M57704H. I installed the module in the 28 - 432 MHz transverter:
A good heatsink is required. For the first time I used the repeater shift mode of the FT450. For 70 cm repeaters, in The Netherlands the repeater shift is 1.6 MHz. I also had to insert the CTCSS frequency of 88.5 Hz. I made a short QSO with PA0WBS via the Rotterdam repeater (430.300 MHz out).
A quick measurement showed that the transverter delivered 15 Watts RF. Now, the challenge is to work in digimodes and see what is possible (FT-8 in particular).
See bg7sgm.taobao.com and eBay for more RF products from BG7SGM (use google translate!).
I started to work on a transverter that converts 28 MHz (10 m band) to 432 MHz (70 cm band). I use a FT450 to process the 28 MHz signals. At 432 MHz the transverter is capable of delivering about 5 Watts RF. A Power Supply Unit from an old PC was used for the 12V/12 Amp and 5V/20 Amp electrical power supply .
First results are promising. I could listen to repeater signals in FM. I hope it will be possible to work with digimodes later on. I will consider adding a PA stage to increase the RF output (to 10..20 Watts).
They broadcast rock music from the '50-'80s. This is a small radio broadcast station located near Dordrecht. They transmit with 100 Watt RF power on 1287 kHz. I discovered that they can be received on my car radio receiver on various locations in Zeeland and Zuid-Holland. In the evening/night they are often 'overruled' by a Spanish station. https://kilrock.nl/