Re: [time-nuts] 5065A Rb Cavity RX - Varactor repair
On 10/23/2020 3:52 PM, paul swed wrote: Corby I have run into issues with the older coax essentially rotting internally. It allows teh center conductor to tough the outer in the worst case. Is FWIW, in those days HP had its own internal shop that made wire and coax. This situation could account for coax "rotting" due to substandard processes inside HP. IMHO, this shop was justified more by the act of customizing, rather than quality. This could be color coded coax, that is unobtainable in the merchant market. They could make triple shielded coax that is similarly unobtainable. Also, the famous mint gray RG-58 double shielded lab jumpers. Fortunately, when it came to custom connectors for the custom coax, they contracted it out to connector vendors, AFAIK. Rick N6RK ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] 5065A Rb Cavity RX - Varactor repair
Corby I have run into issues with the older coax essentially rotting internally. It allows teh center conductor to tough the outer in the worst case. Is that a concern from your experience? HP 3586 slvm as an example. How hard was it to get that unit out. (Hoping I never need to actually do this) Regards Paul WB8TSL On Fri, Oct 23, 2020 at 6:26 PM wrote: > OK, > > Here is a PIX of the cell. > > The front connector is the photocell output and the other 3 connectors > are for the RF drive signal. > > I think if you remove the right hand one you can access the RF probe > directly. > > Inserts show the RF probe, and a couple holes in the threaded side. > > The hole with the brass slotted insert "may" be where the diode is but > not sure. > > Cheers, > > Corby___ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. > ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] 5065A Rb Cavity RX - Varactor repair
If the unit fails again just diconnect the 60Mhz output jack from A3 and Ohm from the center pin to shield on the cables connector with a semiconductor setting on the DVM. Try both directions as the diode can be installed either way. If you can "see" the diode that way it is most certainly good. If not the there are 3 SMC connectors in the route inside the cavity end. Check those for tightness. The diode is NOT easily accessible although the whole cell assy screws out easily. Cheers, Corby ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] 5065A Rb Cavity RX - Varactor repair?
Am 22.10.20 um 23:54 schrieb Richard (Rick) Karlquist: I suspect that the stock 5065 chain has better phase noise than this chip. I know for sure that you can get much better phase noise than this chip by using conventional architectures. Of course they are more complicated, etc. Just wanted to put this chip in perspective. Rick N6RK On 10/22/2020 12:12 PM, Gerhard Hoffmann wrote: This is a ADF5356 with 2 LT3042 to clean up the supply voltage. I measured the successor to this board yesterday on 10 GHz out with my new 1/8 prescaler and the SR620 counter and some As long as you can measure the noise with a 89441A vector signal analyzer instead of a signal source analyzer, it cannot be leading edge. Close-in, it seems quite ok. Enough to guide a 5 MHz crystal oscillator, and also to guide a (in my case) 10 GHz dielectric osc with a Q of 20 to 30K. Sorry, I must stay diffuse at this point. My question for the phase noise in the Engineer Zone was also kinda "scheinheilig", German word, (hypocritical, falsely innocent, ...lost in translation). I know that I could go to a phase detector frequency of 150 MHz with this chip (instead of 20*2), and it would help for sure. But I'm still struggling to make a connection between the Windows evaluation software results and the data sheet. My software driver is 1200 lines of C code (but including lots of comments.) ~400 bits to be set up. And the 100th harmonic of 60 MHz won't be a phase noise wonder either, with or without a SRD. You can see the effect in the well-known pictures of the old HP spectrum analyzers that display a staircase with many a step, depending on the LO harmonic. Sky and MA/COM still make step recovery diodes, whether they fit is a different question. But I cannot think of a special SRD failure mode. If you can do that, solder it out and measure it with a normal Ohm meter. If it still behaves diode-ish, it is very probably a working SRD. Maybe without the soldering, depending on the circuit. Repairing will always be cheaper than transplanting a completely new heart. Cheers, Gerhard ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] 5065A Rb Cavity RX - Varactor repair?
I doubt that the SRD is the problem. It's just the last thing in the chain, and a number of things ahead of it all have to work right first. I'd look first at any connections and wiring between various sections, and jiggle things around to see if the symptoms can return. Next, if ICs and transistors and other parts are in sockets, jiggle them too. For ICs, it's easy to pry one end out slightly - with power off - then press it back in, and repeat at the other end if it seems necessary. Re-wiping the contacts can do wonders sometimes. I don't know if HP ever used the notorious TI IC sockets, but they are a big cause of problems in Tek gear. The same for TI brand ICs that have silver plated leads - whether socketed or soldered in, these can suffer connection failure. This is well known and discussed a lot over the years. Sometimes an intermittent can be a short instead of an open, with various causes, like errant braid strands on coax, wire clippings, solder gobs, and loose hardware that happen to eventually land in just the right spot. I have found this generally the second most likely fault, after open or poor connections. This is also a type that can happen once, if say a loose item caused the problem, then gets knocked out of place (sometimes to a different place where it can cause a different problem later) by moving the unit or opening it up. The problem in diagnosing an intermittent that came and went only once, is that you'll never know for sure what caused it, unless it can be forced to fail again and stay that way for a while, and tracked down. Or, if you happen to find something rattling around inside that can be blamed. Short of that, the next best thing is to check and clean up anything suspicious, and hope that you hit the actual culprit in the process. Ed ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] 5065A Rb Cavity RX - Varactor repair?
I suspect that the stock 5065 chain has better phase noise than this chip. I know for sure that you can get much better phase noise than this chip by using conventional architectures. Of course they are more complicated, etc. Just wanted to put this chip in perspective. Rick N6RK On 10/22/2020 12:12 PM, Gerhard Hoffmann wrote: This is a ADF5356 with 2 LT3042 to clean up the supply voltage. I measured the successor to this board yesterday on 10 GHz out with my new 1/8 prescaler and the SR620 counter and some ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] 5065A Rb Cavity RX - Varactor repair?
I would tend to agree with the assessment that the SRD is not a high failure rate item. Also, it could experience a faux failure where the fixturing of it corroded such that it was not making good electrical contact any more, but the underlying diode was still good. Cleaning up the contact area could fix that. If the SRD truly failed, the only way to get a replacement would be to cannibalize another 5065. I also agree with the other comment that replacing the whole RF chain would be a major undertaking, having designed several RF chains. Rick N6RK On 10/22/2020 10:06 AM, cdel...@juno.com wrote: Ulf, I have never had a 5065A with a bad or malfunctioning step recovery diode in the physics package. MANY other problems are more likely the cause. Cheers, Corby ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] 5065A Rb Cavity RX - Varactor repair?
Ulf, I have never had a 5065A with a bad or malfunctioning step recovery diode in the physics package. MANY other problems are more likely the cause. Cheers, Corby ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] 5065A Rb Cavity RX - Varactor repair?
Hi The device in the cavity that takes the 60 MHz up to 6.x GHz is a step recovery diode ( SRD ). The actual device used (apparently) was unique to the 5065. One proposed “fix” is to eliminate the whole synth / multiply empire and replace it with a very high resolution DDS generating the 6.x GHz. My guess is that will turn out to be a lot of work …. Bob > On Oct 22, 2020, at 9:59 AM, Ulf Kylenfall via time-nuts > wrote: > > > Strolled into my little lab only to find the 5065A's Red Integrator Limit > light on. Control negative fsd. PhotoCurrent OK. No 2nd harmonic. > > Was just about to power off and start to disassemble the unit. > All of a sudden, the Integrator light went out. Control went to zero > and by pressing Reset, the unit locked with previous 2nd harmonic > level indication. > > What ever the problem was, I do not know. I guess I can fix (redesign) > the synthesizer and replace some semiconductors that have failed > but if the problem is in the Rb Cavity RX unit - Varactor - there is a > problem. From a similar unit (but without the TED) I can see that > some part of the varactor assembly can be dismantled, but then > there are a few tiny screws that seems hard to reach. > > Has anybody repaired the Rx part with the varactor assembly? > > Regards > > Ulf Kylenfall > SM6GXV > > > > ___ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] 5065A Rb Cavity RX - Varactor repair?
Strolled into my little lab only to find the 5065A's Red Integrator Limit light on. Control negative fsd. PhotoCurrent OK. No 2nd harmonic. Was just about to power off and start to disassemble the unit. All of a sudden, the Integrator light went out. Control went to zero and by pressing Reset, the unit locked with previous 2nd harmonic level indication. What ever the problem was, I do not know. I guess I can fix (redesign) the synthesizer and replace some semiconductors that have failed but if the problem is in the Rb Cavity RX unit - Varactor - there is a problem. From a similar unit (but without the TED) I can see that some part of the varactor assembly can be dismantled, but then there are a few tiny screws that seems hard to reach. Has anybody repaired the Rx part with the varactor assembly? Regards Ulf Kylenfall SM6GXV ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
