[volt-nuts] Datron 4808 Opt. 70 without low frequency outputs

David C. Partridge david.partridge at perdrix.co.uk
Sun Jul 23 08:04:50 EDT 2017

An update:

Poking around and looking at the schematic for Opt. 70 it was clear that the Stellex DDS IC isn't used for all output frequencies.   For frequencies 30Hz to 330kHz inclusive, the signal is supplied on the I+ signal line of the Lemo connector (with the reference voltage on V+ - a sine with nasty x-over distortion).  When I checked this at the 4808, there wasn't a signal on the I+ line at the Lemo.

Checking on the motherboard, the signal was present and correct.   It turns out that the wire to that pin of the Lemo socket on the back panel of the 4808 had never seen solder!   It looked OK because it was covered by an insulating sleeve, but it must have moved sufficiently to break contact when I took the rear panel off to get at the key-lock.

Anyway, all now soldered up and working well.

PS to get higher frequencies out of the Opt. 70 source, you just need to press the Store/x100 button (top left corner of lower left keypad).


-----Original Message-----
From: volt-nuts [mailto:volt-nuts-bounces at febo.com] On Behalf Of David C. Partridge
Sent: 20 July 2017 17:59
To: 'Discussion of precise voltage measurement'
Subject: [volt-nuts] Datron 4808 Opt. 70 without low frequency outputs

The Wideband Source for my 4808 appeared not to be working as the 4808 said "Error 9" when I tried to use it.

While trying to work out what was wrong I checked the signals on the 15 pin cable between the 4808 and the Option 70 box.

The signal on pin 9 was noticeable by its absence at the far end of the cable (this is IDIGBUSON_H which should be +5V).  It tells the Opt. 70 box at the far end that the 4800 that's powered on.
Once I replaced the cable the beast woke up but only produces output for
0.34MHz and above.   It is silent at lower frequencies.

Anyone have any ideas?


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