On Wed, Sep 28, 2016 at 4:14 AM, Bob Camp <[email protected]> wrote: > Hi > > You have one of the many MV89A’s with an output problem. To be absolutely > sure of the output, you need to have the scope set to 50 ohm input. If it was > set > to Hi-Z, the output is likely even lower…..
It seems that the scope is 1 MOhm input impedance and is not changeable. I will have to see if we have any 50 Ohm in-line terminators around that I can also borrow. Does anyone think that there is any value in trying to pursue a return and replacement with the ebay seller (being China, it's likely to be a long round-trip time for both messages and parcels) or just live with it and move on (potentially replacing the capacitor later if I get some way of getting the casing open safely). From what Bob and others have said, it seems that most of the MV89's have this problem so it seems unlikely I would get a better one without a lot of trials. Tim > > Bob > > >> On Sep 28, 2016, at 1:38 AM, Tim Lister <[email protected]> wrote: >> >> On Tue, Sep 20, 2016 at 12:56 PM, Bryan _ <[email protected]> wrote: >>> May also want to check the output amplitude. If memory serves me correct it >>> is very common for a capacitor inside this model number to fail. It can be >>> fixed but requires a torch or a pretty heavy duty soldering iron to get the >>> can open. >>> http://www.rbarrios.com/projects/MV89A/ >>> >>> -=Bryan=- >>> >> >> I managed to borrow a Tek TDS 2024B 200 MHz scope from work and hooked >> it up to the output of my MV89A. I get a peak-to-peak measurement of >> 2.3 V which if I have converted it right is ~11 dBm ? Alternatively if >> I turn on the FFT mode on the scope I get a peak value of -2.17 db if >> I am driving the cursor mode correctly. With the 10 MHz from the >> radioshackus GPSDO used for triggering, it takes ~18 seconds for the >> MV89 waveform to drift 1 cycle (this is without anything connected on >> the Uin or Uref pins). >> >> Tim >> _______________________________________________ >> time-nuts mailing list -- [email protected] >> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
