[time-nuts] 5061A Beam Current question

paul swed paulswedb at gmail.com
Tue Dec 11 16:28:05 UTC 2012


Pete Joe sure gave you the answer. So you have fallen prey to the
time-nuttery CS drug.
I would never have thought you would have. So Not that I can out do what
Joe told you.
But on my sad frankenstein of a 5061running on fumes of CS the beam current
is so low that I have to use a magnifying glass to watch the peaks! we are
talking approx 3-4 on the meter and thats with the pot all the way up. I am
amazed that it all locks consistently actually. Its tough so as Joe says
use a solid reference to align the OCXO first.
He also hit all of the singing dc to dc convereters. Its normal. Thats what
earplugs are for. ;-)
Sounds like you are in far better shape.
Regards
Paul
WB8TSL

On Tue, Dec 11, 2012 at 8:46 AM, J. L. Trantham <jltran at att.net> wrote:

> Pete,
>
> There are two HV power supplies, +3500 (A18) and -2500 (A19), both of which
> can 'sing'.  A18 comes on when power is applied and in CS OFF mode.  A19
> comes on when you move to any mode other than CS OFF.  There is also a
> battery back up option, Option 002, that has a battery charger board (A2),
> that can sing when trying to charge 'dead' NiCd's.  It comes on when power
> is applied and in CS OFF mode as well.  A2 can be removed with no effect on
> the rest of the unit to test that theory.  When does your unit start
> singing?
>
> The BEAM I indication can be adjusted by the BEAM I METER pot on the
> control
> panel.  It only adjusts the meter indication, not the beam current.  The
> beam current can be affected/changed by the C FIELD adjustment and by
> following the instructions in the manual to align the oven controller (A11)
> and the Electron Multiplier on the Power Regulator board (A15).  Once
> aligned, adjust the BEAM I METER pot for an 'on scale' indication.  This is
> different on the 5061B where BEAM I METER on the control panel is replaced
> by BEAM I and is, in fact, the Electron Multiplier adjustment.  There are
> different versions of the A15 board, some of which have a pot to adjust the
> electron multiplier and others with fixed resistors.
>
> The change in BEAM I indication as you adjust the COARSE freq can be very
> small.  The larger the beam current, the greater the fluctuation, but it
> can
> still be very small, a division or two.  The figures in the manual are
> quite
> 'magnified' in my experience.  However, I have never played with a 'new' CS
> tube.
>
> The change in BEAM I indication as you adjust the COARSE freq is also very
> easy to miss and it takes only a very small adjustment of COARSE to go
> through the entire range.  My usual procedure is to let the 5061A warm up
> for several hours, in the CS OFF mode, make sure the OCXO is stable, then
> compare it's frequency to that of a GPSDO, then adjust the COARSE freq
> (with
> FINE set to 250) to precisely match the GPSDO.  I have a TBolt that I use
> it's 10 MHz to trigger the horizontal of a scope and put the 5 MHz of the
> 5061A to the vertical.  That done, I then select LOOP OPEN, let the CS oven
> warm up, the BEAM I come up, the 2nd HARMONIC come up, then select CONT
> OPER
> and hit the RESET button.  If the OCXO is 'on frequency', CONTROL should
> indicate zero and you should be on the top of the center peak.  Adjustment
> of the COARSE should then be able to demonstrate the 'peaks' to prove you
> are on the top of the center peak.
>
> I don't recall any 'false' modes that will give an erroneous indication.
> However, I have had failures in the LOGIC board (A14) that have caused
> indication problems.
>
> These units are fun to play with and work on.  They make great 'house
> standards'.  I leave them in CS OFF all the time, which lets the OCXO and
> ion pump run continuously.
>
> Hope this helps.
>
> Joe
>
>
>
> -----Original Message-----
> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
> Behalf Of Pete Lancashire
> Sent: Monday, December 10, 2012 10:59 PM
> To: Discussion of precise time and frequency measurement
> Subject: [time-nuts] 5061A Beam Current question
>
>
> I've got a couple questions on a early S/N 5061A I got a few days ago.
>
> It took a couple days but the Ion Pump current is now down to "zero" or at
> least less then one division on the meter.
>
> I'm able to get the unit to go into continuous operation mode by following
> the TURN-ON PROCEDURES but have a few qestions
>
> 1. The unit 'sings' I'm tone deaf but its a high pitch. It could take some
> doing to isolate where it is coming from. Any ideas ?
>
> 2. How much should the beam current change when turning the OSC FREQUENCY
> COARSE adjustment ?
>
> On time about 45 to 60 minutes
>
> The current scribbled on the door is 19, I'm running pretty much 30. When
> making the adjustment the difference between the peak and any other
> position
> is only plus/minus a max of 2 or 3.
>
> 3 And i guess for last, are there any false modes that will turn off the
> ALARM and turn on the Con't Operation light ?
>
> Thanks
>
> -pete
>
> PS Anyone have a side panel without the front handle broken ?
>
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