[time-nuts] HP5065A

paul swed paulswedb at gmail.com
Wed Sep 28 01:43:34 UTC 2011

Sent my repair pix to the group Magnus.

On Sat, Sep 24, 2011 at 7:09 AM, Magnus Danielson <
magnus at rubidium.dyndns.org> wrote:

> Fellow time-nuts,
> I now have three 5065A in my lab (not all mine) and I can now conclude that
> the A15 PSU board C8, C9 and C10 caps has gone bad on all three. The only
> difference on the first one is that the process has not gone as far as to
> blown the caps, but two of the leads has began the process and turned dark
> purple on the upper half. Also, one of the caps have been replaced by a 220
> uF cap at some time.
> I already have some fashinating photos of the two other boards lying around
> (on Facebook actually...).
> I've already stocked up on replacement caps so replacing them all will be
> my first priority.
> Another difference I've noted is that the last one in (Thursday to be
> exact, arrived with two cesiums from a fellow time-nut) proved much more
> modern. The A15 assembly does not even have the rectifier diodes on it, but
> it has been placed off-board. I think this is to provide better cooling and
> I seriously consider to modify the other two up to that standard. The
> rectifier diodes don't get sufficient cooling as it sits in its compartment,
> all sides but the top being closed and then only perforated holes for
> self-convection.
> Mounting the rectifiers onto the large aluminium frame would better cool
> them over time.
> Another surprice in the later 5065A is the 5061-106 retrofit, where the 105
> oscillator is being replaced with a 10811 oscillator. Will be fun to compare
> against the older variants.
> Lack of time for lab duty and lack of space in lab is main obsticle right
> now, but it's fun with some progress at least.
> Once I got these three rubidiums of the actual bench, there is a bunch of
> cesiums to investigate.
> Need to come up with a suitable measurement rig for all this now. This
> morning I was considering the use of either one of my 5,000055 MHz OCXOs or
> the 5,000055 MHz out of the TS-105A rubidium (BNC on the back) to set up a
> DDMTD system with a bunch of channels. I start to need it for real now...
> Cheers,
> Magnus
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