UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post

nigelpritchard · 11th Jan 2020, 4:30 pm

I'm hoping the RF Amateur Radio fraternity (probably only from the UK) might include someone who recognises an ancient RF dummy load that I've had for years and not used. I've posted some photos.

It is a "50-ohm" tapered slab-line device made with a 52 ohm carbon rod which has a tap at about 40% from which a germanium detector circuit and an Acorn glass thermocouple (Ormandy & Stollery style) power measurement circuit are connected. RF input is via N-socket. The slab-line is in very thick, and solid, silver-plated brass and there is also a RF sampling connector with capacitive proximity take-off at the top end of the carbon rod leading to what I believe is a Burndept Pattern-12 plug/socket.

It appears to have been made for the UK WD by EMI and has a Cat number of 6C/C33851 and manufacturing date of "ZD".

As you might see from the photos it is unlikely that the frequency response is very great because the feed to the thermocouple is somewhat lengthy. I'm hoping to get a bit more info about this assembly and in particular some idea of the bandwidth to be expected.

I could put the dummy load on my NanoVNA to look at it's parameters but that won't tell me what frequency the power-measurement circuit can work at.

Any ideas welcome. Regards G8AYM

11th Jan 2020, 4:30 pm	#1
nigelpritchard Diode Join Date: Jan 2017 Location: Aylesbury, Buckinghamshire, UK. Posts: 7	RF Dummy Load Identification I'm hoping the RF Amateur Radio fraternity (probably only from the UK) might include someone who recognises an ancient RF dummy load that I've had for years and not used. I've posted some photos. It is a "50-ohm" tapered slab-line device made with a 52 ohm carbon rod which has a tap at about 40% from which a germanium detector circuit and an Acorn glass thermocouple (Ormandy & Stollery style) power measurement circuit are connected. RF input is via N-socket. The slab-line is in very thick, and solid, silver-plated brass and there is also a RF sampling connector with capacitive proximity take-off at the top end of the carbon rod leading to what I believe is a Burndept Pattern-12 plug/socket. It appears to have been made for the UK WD by EMI and has a Cat number of 6C/C33851 and manufacturing date of "ZD". As you might see from the photos it is unlikely that the frequency response is very great because the feed to the thermocouple is somewhat lengthy. I'm hoping to get a bit more info about this assembly and in particular some idea of the bandwidth to be expected. I could put the dummy load on my NanoVNA to look at it's parameters but that won't tell me what frequency the power-measurement circuit can work at. Any ideas welcome. Regards G8AYM Attached Thumbnails