fluke 606xA adjusting the 10MHZ synthesizer oscillator and drift.

[charlyd]

hello i have a question about the 10Mhz synthesizer oscilator adjustment for  a fluke 6062A ( no  option 130 & 132 installed ).

how stable is the 10MHZ Xtal adjusted with C240
and how is the drift on adjusted with R230 ( mine keeps on drifting to the right and then to the left??)

Who has a 6062A ( or 6061A ) without the options high-130  and medium-132.


did you ever troubleshoot this part of the generator...if yes..

suggestions wanted... what is normal behavior and what is not?

[SaabFAN]

If I understand this correctly, the adjustable capacitor is only a coarse adjustment. The fine adjustment and stability comes from chip U70, which is a analog switch.
Without further information, I suspect the problem in 3 places:
- R230 is toast. Happens to Potentiometers when they get old.
- U70 doesn't select the right source of the adjustment-signal.
- The select-logic for the reference-signal isn't working correctly and connects what seems to be a PLL to the Oscillator-Control.

I'd start with the voltage at pin 11 of U70. If that voltage is not constant, you got the culprit. Next would be Pin 4 of U70 - Check that for the right level. The DG301 is available at Mouser, including datasheet: https://www.mouser.de/ProductDetail/Vishay-Siliconix/DG301BDJ-E3?qs=sGAEpiMZZMtxrAS98ir%252bs0szLGzxh%2fuDaZXwrGmy8Ek%3d

[Stray Electron]

  My 6061 (std model) shows very good stability against my HP 5343A (option 004 & 011).  But I'm n0t sure how accurate they are until I get a GPSDO to check them against.

[charlyd]

sorry it took a long time.. to be back.. but i started picking up the problem again:  this is the schematich from the 10MHz part.
U70 output pin2/pin13 output is very stable. 

so ? if there is the problem… has anybody ever had broken varicap CR22 & CR28 diodes..?

(I am also still looking for the "130 High Stable Reference board" if somebody has this board please let me know.)

[charlyd]

so last weekend i took the board out it took me 45 min.    then i placed the U70 on a socket and replaced CR22-CR28 and the 10mhz BLiLey BK3-1B crystal.
tomorrow i will have a look for the adjustment of R230 against the drifting.. but from what i saw it is not yet gone….

 

[charlyd]

Hello can anyone tell me how accuracy & stable this  fluke / gigatronics 606xA  unit is.. for example on  a

- 500Mhz what is it allowed to drift?
- 2.1GHZ (for 6062A) what is it allowed to drift?

and also for  the power level.
i am curiuos what i can expect, and then not what i can read in the specs, but what these units really do.
we call that not in theory but in practice.

[wn1fju]

As far as frequency drift is concerned (with the standard crystal oscillator), my Fluke 6060B drifts quite a bit until it is warmed up.

Fluke 6060B 10 MHz reference output jack on back panel feeding an HP 5335A counter (with ovenized oscillator):  From a cold start, I let the 6060B
warm up for one hour.  The unit then drifted about 16 Hz until it seemed to stabilize after four hours.  Then the drift was about 0.7 Hz for the next hour
(with about 0.1 Hz the last 40 minutes).

The spec calls for +/-5 Hz (0.5 ppm x 10 MHz) drift over one hour.  I believe the 606x units will meet that spec comfortably - but only after it has warmed up
for at least several hours.  The expected drift at any arbitrary output frequency would then be less than 0.5 ppm times the frequency.

I didn't check the amplitude drift.  I would expect it to be neglible.  And since the accuracy spec is +/-2.5 dB, any drift would be trivial in comparison.

[charlyd]

thanks to all replies great work guys..!  this brings me to do some more testing.

- picture 1 i powered on the unit in the 500Mhz position and this is what happened.

- picture 2 i connected to the REF out on the backside

- picture 3 i took the ref out from my 53181A counter and connected to the ext in ( backside of the 6062A ) switched the 6062A in 500Mhz
  ( rock stable)


is that a known issue with the R230 and U70    as SAABFAN wrote above.

now my ovenized osc.  is on J110   ( added the schematic again in just a better quality)

[charlyd]

after replacing U55. -  DM74S04N.
the drifting was solved, even without option 130 after warmup of course 15min. only last digit.

the power out is noisy in the lower freq range. details will follow.

any suggestion?

[charlyd]

i so when the 10Mhz was fixed,  i discovered below 245Mhz my signal was not stable or let s say very noisy. After hours i found a open circuit arround the LPB filter. then my signal was great again. that nearly finished the project.

reset [RCL][9][8] result:    30   -  300.000.00   -10.0
----------------------------------------------------------------------------------
pushing the status button  i saw :  000   000   000   ->   Job done i thought

but no, i still have an amplitude issue.

i am curious if these units when i [press] status it displays 000 000 000  and i dont have a "uncal".. but

my amplitude is very low between  62.4mV - 251mV   below 62.4 it is ok and above the 251mV. i did test the latch part and the relays kick in when needed.

anybody experience with a problem like not having a stable amplitude..

[SaabFAN]

According to this page http://wera.cen.uni-hamburg.de/DBM.shtml 62 to 251mV is a range of pretty much exactly 12dB.

So I'd say there's an intermittent contact in the attenuation-part of the 12dB mechanical attenuator.

There are a few videos made by TheSignalPath on Youtube, where he shows how these attenuators work and I think he also repaired one or two.

You can probably verify this by gently hitting the attenuator with the grip of a screwdriver or rubber hammer - you should see changes in amplitude if the RF-Switch has a contact-problem.

[charlyd]

hi today i too out the att. relay block and it seem 1 off the relay response really weird.. time for a relay swap.. 
so i need 1 relay  but maybe if the price is not TOO high swap them all.
we wil see.

WANTED..
i am in the need of a GENICOM 3SDS5002G1 relay they are difficult to find so my shout out here if somebody can help me out and sell  1 or more of these relays or compatible
they are type            DPDT - 18v  coil 880 Ohm

i will add a picture of the relay ( under a microscope )  and the output board.

if somebody has an output for sale from a broken fluke also ok.

please PM me if you can help me out

[rf+tech]

Take a look at Teledyne EMR selection Guide, many high-reliability metal-can options available, for DC to a few GHz applications.

https://www.teledynerelays.com/Datasheets/EMR%20Selection%20Guide.pdf

It will be necessary to determine if the original relays are latching or non-latching.

RF+ Tech

[charlyd]

rf+tech, thanks for you reply. if you mean by latching  if the relay click in at the right moment.  yes i checked out the whole table.

but what i suspect the last moment is, can it be that as per latch the output at the beginning of the attenuator / RPP assembly . ( so the output)  is regulated,
probing at that point i get : 

 ->  =  stepping down in AMPTD 

2.207 volt -> 620mV   [click]   1.1670 volt -> 589mV  [click]   1.116 volt -> 565mV   [click]  1.097 volt ->  ...and on...   

in total there is an attenuation of 138dBm      6 - 12 -24 - 24 - 24 -24 -24   the last five 24dBm i can toggel with SPCL 83 - 86

can it be that one is a bit off?  so i can correct it  ( sort of reprogram it...   anybody experience with that ?   there is also a SPCL 90/91  95/98

i did  NOT dip any switches like #6

any tip is welcome

[rf+tech]

Non-latching relays must have power applied to the coil, to maintain N.O. contacts in a closed state and vise versa.

Latching relays contain a small magnet, to maintain contact state. These do not require the coil to be energized continuously. Some latching relays contain two coils, one to close and the other to open. Single-coil latching relays require reversal of DC polarity to the coil, to change state.

As for the remaining part of your post: mixing volts and decibels makes for difficult interpretation of data. Seriously, please express all RF measurements in dBm for absolute levels and dB for incremental differences. Doing so will reveal details at a glance, without the need to reach for a calculator.

Also, when using non-obvious mnemonics, show the rest of us the courtesy of explaining their meaning. RPP?? SPCL?? WTHDTM?

RF+ Tech

[charlyd]

thank RF+tech, thanks for the tip yes indead i need to keep it to one measurement value.  i didn t have a Power meter yet so i couldn t go for 100% dBm but now it would be much more easy todo.

the codes [SPCL]  stand for Special function mode. and RPP assembly is relay driver board.

[charlyd]

Hi the topic is old but i never did a follo-up on it..  i got myself an other  attenuation/output board like in post #11 and didn t have the time to swap it still.
will be continued....