[time-nuts] 5370A vs 5370B
paul swed
paulswedb at gmail.com
Wed Mar 10 01:48:30 UTC 2010
Bob how long has it been on
I think it needs to be stable like about 30 minutes
On Tue, Mar 9, 2010 at 8:37 PM, Bob Camp <lists at rtty.us> 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 -- time-nuts at febo.com
> > To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> > and follow the instructions there.
> >
>
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>
More information about the time-nuts
mailing list