Advance UHF Millivoltmeter VM 79

[Skywave]

Maybe that price [£1125.0.0] is a mis-print . . .

. . . and I suspect that it is. The advert I read did have a number of obvious errors in it which I corrected, prior to re-presenting it here. I also distinctly recall that at that time, small ads. in mags. (such as PE) often had similar errors - most were obvious, but some weren't.
£1125.0.0 . . . probably too many "1"s: an easy typo to make, especially if the ad. was written in a hurry. To me, £125.0.0 sounds much more likely & believable.
Al.

[AlanBeckett]

Manual on order.
We shall see what we shall see

Alan

[pwdrive]

Hopefully Alan it will contain the probe details if the original probe isn't forthcoming.

Lawrence.

[AlanBeckett]

I trust so.

Alan

[Yorkie]

There are full details of the Boonton probe at the link in post #14, but I suspect that finding the BAT32 Schottky diodes will be the challenge.

http://members.shaw.ca/novotill/RfProbeS.../index.htm

Couldn't find any sources of the diodes, but plenty of sources of the data sheet, eg:

http://pdf.datasheetcatalog.com/datashee.../BAT32.pdf

Other than the diodes, just three caps & four resistors, plus a bit of metalwork which is right up your street Alan, and you're sorted.

[camallison]

I did a deep trawl and came up with a series of Schottky didoes used in such probes (I think). Maybe a trawl of their datasheets will reveal a BAT32 equivalent among them?

BAT32, BAT63, 1SS99, 1SS16, SMS1546

Colin

[AlanBeckett]

I've used a lot of Schottky Diodes over the years but never Small Signal ones at high Frequencies.
We'll see what the Probe requires.

Yes David, I just hope that the Manual has at least a Schematic for the Probe and hopefully some sort of Picture and/or exploded Diagram.
The Probe Socket isn't anything special so I'm hopeful that I can produce something reasonable.
Alan

[Refugee]

There may be a little bit of bias needed to overcome the forward voltage of the diode.
The connector looks like a 3 pin type and there is also a DC socket next to the probe socket.

[AlanBeckett]

The Socket next to the Probe Socket is marked 'DC OUT'.
On the VM77s there was an 'Amplifier Out' Socket so it may be the same thing, or it might be a DC Supply for the Probe or other Attachments.
We'll see when I get the Manual.

Alan

[pwdrive]

Zero bias Schottky diodes are available, I think that Farnell might do them (can't remember the the number) they have a low PIV rating, I did come across a data sheet for them on the web, good to 1.5 Ghz I think, if I can find the data sheet I'll post it up.

Lawrence.

EDIT: http://pdf.datasheetcatalog.com/datashee...kswffy.pdf