Rogers Ravensbrook FM Tuner - stock faults? Schematic?

[Arqiva BOC]

Hi All,

With my shiney new to me Revox, I can now take my Ravensbrook down for a well deserved overhaul,

Trouble is, I can't seem to find a circuit diagram/service manual for it. Can anyone help me out with that?

Can anyone also point out any stock/common faults? Mine has a tendency to work for a while before making a bit of a clunk noise and either going quiet or no audio out, it usually comes on again ok if I turn it off and on again. Caps suspected as per the norm!

Any advice cheerfully received!

Martin

[Nickthedentist]

Are you sure it's not the interstation muting cutting in as it drifts off tune?

I used to have a whole load of Rogers data which they kindly sent me FOC about 25 years ago (long after the equipment was pretty much obsolete), but I lent it to someone who was starting a Rogers website and never saw it again.

N.

[Martin G7MRV]

Dont think so, it doesnt come back easily if I try retuning

[Synchrodyne]

I have the schematic for the Rogers Ravensbrook FET FM tuner, so please send me a PM and I’ll email a scan.

That schematic is undated, so I do not know to which iteration it applies. However, it seems to align with the general circuit description given in the Gramophone 1971 March review, so I imagine that it is for the early version.

Evidently the Ravensbrook was a trimmed down version of the Ravensbourne 2 FET FM tuner. Whereas the latter used dual-gate mosfets in both the RF and mixer stages, the Ravensbrook had a single dual-gate mosfet in the RF stage. It had a “more integrated” IF strip, based upon a CA3012 plus CA3014 combination, whereas the Ravensbourne had four µA703 stages and a discrete ratio demodulator. Given that the Ravensbrook postdated the Ravensbourne by a year or so, and at a time when integration in consumer products was moving up a step curve, that seems logical, but the paradox was that the RCA CA3014 et al actually preceded the Fairchild µA703 by maybe half a year or so. The Ravensbrook also deleted the MPX filter.

Cheers,

[Arqiva BOC]

Hi, PM sent, thanks

I didnt realise it dated from quite so far back, this one came out of live monitoring service just last year!

[Nickthedentist]

That's incredible.

I had one of these until recently and whilst I found its performance reasonable, it was nowhere near as sensitive or selective as the older Ravensbourne, nor as most halfway decent Japanese competition. The matching amp was also very noisy. Lovely build quality and styling though.

Have you got any freezer spray? This can sometimes be very revealing with this type of fault.

Nick.

[Synchrodyne]

The Ravensbourne FM tuner was released either very late 1967 or early 1968. E.g. its advent was recorded in Wireless World 1968 April. It must have been one of the first UK FM tuners to use dual-gate mosfets.

The Ravensbrook FM tuner I think dates from 1969, around the same time as the Leak Stereofetic, although I can't now find a specific reference.

Another difference was that the Ravensbourne had a 4-gang front end, whereas the Ravensbrook was 3-gang.

The Ravensbourne was updated in the early 1970s, I think to use the CA3089 or similar IF subsystem and probably the MC1310 PLL decoder. I am not sure what happened to the Ravensbrook in updating terms, though.

Cheers,

[Synchrodyne]

I should have looked first. The attached excerpts from the Rogers 1973 catalogue show that the Ravensbrook tuner had a similar updating, including quadrature demodulator and PLL decoder.

So if the Ravensbrook at interest has a quadrature demodulator (CA3089, TAA661 or something similar), then it would be from of the second iteration.

Cheers,

[Nickthedentist]

Fascinating scans, thank-you!

The Ravensbrooks pictured have round pushbuttons, whereas the earlier ones had square, brown ones ISTR.

[Arqiva BOC]

The one I have is the one pictured in the Rogers '73 ad top right. It doesnt look like the one on the Ravensbrook tuner and amp ad.

[paulsherwin]

Originally Posted by Nickthedentist

I had one of these until recently and whilst I found its performance reasonable, it was nowhere near as sensitive or selective as the older Ravensbourne, nor as most halfway decent Japanese competition. The matching amp was also very noisy. Lovely build quality and styling though.

These things seem to have quite a following in some quarters. I've no idea if such a reputation is deserved though.

Off air monitoring doesn't need broadcast quality professional kit, just good mid market hifi.

[Nickthedentist]

I suppose mine could have been a duff one. It went to someone here... Perhaps they'd like to comment?

N.

[Synchrodyne]

Here are the other pages from the 1973 Rogers catalogue, and also the Gramophone reviews of the original versions of the Ravensbourne and Ravensbrook tuners.

Cheers,

[paulsherwin]

For info, you can stop the forum software resizing your scans by zipping them or saving them as PDFs.

[Synchrodyne]

Thanks for that, Paul, and I'll repost these items accordingly.

I have found that even when I use Irfanview to resize jpegs, the forum software still squeezes them even more.

Cheers,

[Synchrodyne]

Here is the Rogers 1973 catalogue as a .pdf, and I trust more readable.

Cheers,

[Synchrodyne]

And here are the Gramophone test report pages, zipped.

Cheers,

[Nickthedentist]

Much better, thanks!

[Martin G7MRV]

Thanks for the pics - It turns out I have the Ravensbrook II combined Tuner and Amp!