This has been an interesting talking point at my local radio club (HARS ).
My dad Les G6SXB and myself have used this as an attenuator for 10 years plus.
We have been told it is a filter.
It is interesting that it seems to work as either
Being tuned as a filter or an attenuator.
I would be interested hearing from anyone as this was a copy from Microwave Modules unit.
I set about building the filter and used a tobacco tin.
If you look in the picture i have soldered earth connections where the 75 ohm coax come into the tin.
Also soldered an earth near where the coils are soldered.
Each coil was wound around a drill bit to the size in G8MNY's paperwork.
Next each coil is soldered to a trimmer cap and then soldered to the tobacco tin.
Scrape the tin to ensure good soldered connection.
You will notice i have not used Polo mint size ferrite cores.Instead i have used clip on ferrites.
The filter below is made for 6m , 4m , 2m & 70cm.
Tune each coil on each band by adjusting the trimmer or opening and closing the coils.
If you run a preamp on your tv put the filter in before the preamp then adust.
I would be interested if anyone else has made one of these filters and how well it worked for them.
I have been interested in SSTV & FAX since i got interested in Radio.
Myself and my dad Les G6SXB had a great mentor. Richard Thurlow G3WW.Richard was one of the leading experimenters of SSTV at that time.
This inspired us to try out SSTV. First of we used a Spacemark type SSTV unit and later a ZX 48k Spectrum.
We then moved up market and brought a Wrasse SC1 SSTV Converter.
Now days Les and myself are now using MMSSTV program.
Click on MMSSTV Website
The MMSSTV program is free to download and use.
Here are a few pictures Les has worked on HF
Radiofax, also known as HF FAX, radiofacsimile or weatherfax, is a means of broadcasting graphic weather maps and other graphic images via HF radio. HF radiofax is also known as WEFAX, although this term is generally used to refer to the reception of weather charts and imagery via satellite.
The program i use to decode HF Fax is FLDIGI. It is free to download .
Click here for FLDIGI Download
Tune frequency 1.9khz lower.
Click on link below for :