Mystery MSF receiver - UK Vintage Radio Repair and Restoration Discussion Forum

KeithsTV · 2nd Dec 2025, 12:20 pm

I've recently acquired an MSF clock built by my father-in-law many years ago. It came in two cases, a receiver and the decoder display. It works but there is a fault in the display which I think is the actual 7 segment displays but having opened up the case it looks like a CMOS logic IC based decoder and looks a "mess".

However the receiver looks as if it was a magazine project and has what I assume is a professionally produced PCB. I'd imagine it would have been published in the 80's.

Can anyone identify the PCB and suggest in which magazine it was published or point me in the right direction for the circuit as I'd like to reuse the receiver with a more modern decoder.

Keith

turretslug · 2nd Dec 2025, 2:10 pm

Ambit published a design for a two-part MSF clock (receiver and decoder/display), the "Rewbichron" in the early '80s in Radio and Electronics World- they were also agents for Toko coils.

G6Tanuki · 2nd Dec 2025, 2:25 pm

I wonder if the name Rewbichron hints at it being a circuit from Radio and electronics World magazine?

If so, scanned copies of said mag are available at the American Radio History site.

KeithsTV · 2nd Dec 2025, 7:21 pm

I'm pretty sure that it's not the Rewbichron as that receiver is a single IC superhet whereas this receiver looks like it's a TRF.

Also the Rewbichron decoder uses a micro whereas this one is discrete logic ICs.

I suspect I'll have to trace out the circuit.

Keith

KeithsTV · 2nd Dec 2025, 7:23 pm

There is also an MSF receiver shown in the 98/99 Maplin catalogue but that one is also a superhet.

Keith

TonyDuell · 2nd Dec 2025, 7:39 pm

There was a Rewbichron II which had a single-chip receiver (that I could never get to work properly) and a Z80-based decoder/display. I got the kits from Cirkit back in the late 1980s.

Maplin published at least 2 designs for MSF receivers in their magazine. I built the earlier one which, IIRC used an NE567 to detect the 60KHz signal. That one worked fine after I'd replaced the capacitor associated with said PLL with one that had a low temperature coefficient. The one in the kit would drift so far as to prevent the thing from working with a soldering iron held about an inch away. I think the later Maplin design was a superhet.

The board in this thread is none of those. If there was an earlier Rewbichron then it might well be that one.

KeithsTV · 3rd Dec 2025, 12:22 pm

I've just had another look at the receiver and it looks as if it is a superhet. The single Toko coil is the local oscillator running at around 64kHz giving an IF of about 4kHz. There is an audio output from one of the op amps with the second op amp acting as a detector with a square wave output to feed the clock.

Time to start drawing out the circuit.

Keith

2nd Dec 2025, 12:20 pm	#1
KeithsTV Nonode Join Date: Aug 2007 Location: South Bradford, West Yorkshire, UK. Posts: 2,622	Mystery MSF receiver I've recently acquired an MSF clock built by my father-in-law many years ago. It came in two cases, a receiver and the decoder display. It works but there is a fault in the display which I think is the actual 7 segment displays but having opened up the case it looks like a CMOS logic IC based decoder and looks a "mess". However the receiver looks as if it was a magazine project and has what I assume is a professionally produced PCB. I'd imagine it would have been published in the 80's. Can anyone identify the PCB and suggest in which magazine it was published or point me in the right direction for the circuit as I'd like to reuse the receiver with a more modern decoder. Keith Attached Thumbnails

2nd Dec 2025, 2:10 pm	#2
turretslug Dekatron Join Date: Nov 2011 Location: Cambridgeshire, UK. Posts: 4,757	Re: Mystery MSF receiver Ambit published a design for a two-part MSF clock (receiver and decoder/display), the "Rewbichron" in the early '80s in Radio and Electronics World- they were also agents for Toko coils.

2nd Dec 2025, 2:25 pm	#3
G6Tanuki Dekatron Join Date: Apr 2012 Location: Wiltshire, UK. Posts: 15,758	Re: Mystery MSF receiver I wonder if the name Rewbichron hints at it being a circuit from Radio and electronics World magazine? If so, scanned copies of said mag are available at the American Radio History site. __________________ "It's not true that I had nothing on. I had the radio on!" -Marilyn Monroe .

2nd Dec 2025, 7:21 pm	#4
KeithsTV Nonode Join Date: Aug 2007 Location: South Bradford, West Yorkshire, UK. Posts: 2,622	Re: Mystery MSF receiver I'm pretty sure that it's not the Rewbichron as that receiver is a single IC superhet whereas this receiver looks like it's a TRF. Also the Rewbichron decoder uses a micro whereas this one is discrete logic ICs. I suspect I'll have to trace out the circuit. Keith

2nd Dec 2025, 7:23 pm	#5
KeithsTV Nonode Join Date: Aug 2007 Location: South Bradford, West Yorkshire, UK. Posts: 2,622	Re: Mystery MSF receiver There is also an MSF receiver shown in the 98/99 Maplin catalogue but that one is also a superhet. Keith

2nd Dec 2025, 7:39 pm	#6
TonyDuell Dekatron Join Date: Jun 2015 Location: Biggin Hill, London, UK. Posts: 6,062	Re: Mystery MSF receiver There was a Rewbichron II which had a single-chip receiver (that I could never get to work properly) and a Z80-based decoder/display. I got the kits from Cirkit back in the late 1980s. Maplin published at least 2 designs for MSF receivers in their magazine. I built the earlier one which, IIRC used an NE567 to detect the 60KHz signal. That one worked fine after I'd replaced the capacitor associated with said PLL with one that had a low temperature coefficient. The one in the kit would drift so far as to prevent the thing from working with a soldering iron held about an inch away. I think the later Maplin design was a superhet. The board in this thread is none of those. If there was an earlier Rewbichron then it might well be that one.

3rd Dec 2025, 12:22 pm	#7
KeithsTV Nonode Join Date: Aug 2007 Location: South Bradford, West Yorkshire, UK. Posts: 2,622	Re: Mystery MSF receiver I've just had another look at the receiver and it looks as if it is a superhet. The single Toko coil is the local oscillator running at around 64kHz giving an IF of about 4kHz. There is an audio output from one of the op amps with the second op amp acting as a detector with a square wave output to feed the clock. Time to start drawing out the circuit. Keith