[time-nuts] HP-3336A Manual
gbusg at comcast.net
Mon Jul 16 17:50:31 EDT 2007
I was last involved with a 3336A about 12 years ago, so I hope I can still
remember the correct situation (but no guarantee).
As I remember it, there are some relays in that aluminum box between the
circuit board and the front panel 75, 135 and 600 ohm outputs. If you have
the older, tall, yellow plastic relays in there, then those relays might be
your problem -- they were not reliable over time. But if you have the newer,
black low-profile Omron relays, then you've got good relays (that are far
less likely to fail).
Given your symptom, I'd guess you have the older, tall, yellow plastic
relays. If I remember correctly, that version relay clips to the PCB and its
gold leaf contacts actually touch pads on the PCB -- so the PCB itself
becomes part of the relay action. The newer, black Omron relays are potted,
completely self-contained, and are soldered into a re-designed board.
BTW, if your unit has the option 005 precision attenuator, then the
precision attenuator is an aluminum cast base, with solenoids on top (and a
removeable cover for access to the solenoids) and a factory-only-repairable
main channel milled-into the aluminum base, with the attenuator pads in the
form of laser-etched substrate pads that fit into the channel. ...The
solenoids push various gold-plated leaf contacts against the small contact
pads on the substrate pads.
----- Original Message -----
From: "Tom Clifton" <kc0vsj at yahoo.com>
To: <time-nuts at febo.com>
Sent: Monday, July 16, 2007 1:16 PM
Subject: [time-nuts] HP-3336A Manual
I perused the pdf manual and came up more confused
than when I started...
My problem seems to be in the Option 005 high
precision attenuator (as I can best tell). There is
an aluminum box between the circuit board and the
front panel 75 ohm, 135 ohm and 600 ohm outputs. That
mysterious 'box' seems to be open. I'm not sure if
it is just an impedence matching assembly, or if it
includes the option 005.
As the front panel level control is changed, the raw
50 ohm board output measures between +5 and -5 dbm and
every time the display crosses a -3dbm threshold (-3,
-13, -23 etc) you hear a relay click and the raw
output jumps back up 10db.
Hope that clarifies more than confuses...
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