Hi That was my thought.
I've seen pictures of a number of 5370's reading their internal oven "off". I suspect is only going to take a few weeks of reading to find the magic pot. Bob On Mar 9, 2010, at 8:57 PM, John Miles wrote: > It should be good to go right away, if working properly. > > If it were measuring an independent 10 MHz source at 99.998xxx MHz I would > suspect the thermal fuse in the 10811.. but if it's measuring its own > reference, I'm not immediately sure what would be up with that. It would be > time to start going through the manual at that point. > > -- john, KE5FX > >> -----Original Message----- >> From: [email protected] [mailto:[email protected]]on >> Behalf Of paul swed >> Sent: Tuesday, March 09, 2010 5:50 PM >> To: Discussion of precise time and frequency measurement >> Subject: Re: [time-nuts] 5370A vs 5370B >> >> >> I think it has to warm up for about 30 minutes >> Seem to recall interpolators maybe not just seems like that >> >> On Tue, Mar 9, 2010 at 8:37 PM, Bob Camp <[email protected]> wrote: >> >>> Hi >>> >>> Ok, the trigger level pots are bent but functional. The one >> that was stuck >>> works after a bit of readjustment of the knob. >>> >>> All three inputs (ext arm, and the two channels) blink when I >> put the 10 >>> MHz into them. The two with the working pots behave as expected >> as the pot >>> is turned (trigger in the middle, no trigger on both ends). >>> >>> For what ever reason it seems to think that the period of it's 10 MHz >>> standard is 99.5 ns. In frequency mode it thinks the standard >> is at 9.998xxx >>> MHz. Obviously it's a little confused .... >>> >>> Sounds like it's worth working on, unless the 99.5 ns thing >> indicates some >>> sort of massive failure. >>> >>> Bob >>> >>> >>> On Mar 9, 2010, at 7:03 PM, Mark Sims wrote: >>> >>>> >>>> I've had the "pleasure" of fixing way too many 5370A and 5370B front >>> panels. It's been a while so these musings may be clouded... >> also beware >>> of the two or three different front panel designs. Also there >> are "hybrid" >>> 5370A's out there with 5370B front ends. >>>> >>>> There are 4 pots on the front panel: the 470K display update rate, a >>> 10K or 200 ohm arming level (200 ohm on 5370B and later >> 5370A's), and two >>> 5K trigger level. All are linear taper, all have switches, >> all are small >>> pots with (1/4"? bushings). Finding pots with proper switches >> ain't easy. >>>> >>>> I have never had to do the trigger level pots. They have metal shafts >>> and seldom break. Their switches are what you would expect >> (closed when the >>> pot is turned clockwise). In the far CCW direction the switch >> is open and >>> selects the 0V trigger level. >>>> >>>> The other two pots are an exceedingly crappy hp design. They have >>> fragile plastic shafts and really poor quality switches. The >> switches need >>> to be closed when the switch is counterclockwise. HP's pots have both >>> normally open and normally closed contacts. Frankly these >> pots are seldom >>> used and you can use a switchless pot and just hardwire those pads. >>>> >>>> The display rate pots is particularly useless. You can just >> hardwire it >>> to max. >>>> >>>> The biggest bugaboo in buying a 5370 is the state of the HP >> custom input >>> amplifier chips. They can be damaged by overloading the input. >> Blow one >>> and you are screwed. Buy a 5370 with a blown input amp and you >> are screwed. >>> The 5370A and 5370B used different chips. The 5345A counter >> is a source >>> of input amp chips. >>>> >>>> It would be VERY nice if some clever person built drop in replacement >>> "chips" built of modern SMD parts on a DIP header. Those input >> amp chips >>> are socketed. They are little more than a comparator. >>>> >>>> Quick check of the 5370A inputs is to set the unit to >> "SEParate" inputs >>> and connect the back panel 10 MHz ref signal to each of the inputs. The >>> signal level LED should flash. A steady LED means that input >> is toast (or >>> the input PCB slide switches are full of navel lint and need cleaning). >>>> _________________________________________________________________ >>>> Hotmail: Free, trusted and rich email service. >>>> http://clk.atdmt.com/GBL/go/201469228/direct/01/ >>>> _______________________________________________ >>>> 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. >> > > > _______________________________________________ > 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.
