Magnus out of curiosity I checked and those transistors are available on
ebay and other sites at reasonable prices. At least in the US. So thats
great news for you.
Regards
Paul
WB8TSL

On Tue, Jan 14, 2020 at 9:22 PM Magnus Danielson <mag...@rubidium.se> wrote:

> Hi Paul,
>
> Lacking the specific transistor 2N3553 I can for the moment not progress
> with the rubidium lamp. It's very obvious that the oscillator is not
> oscillate and hence the lamp is not giving light.
>
> A friend might have those in his way to extensive component storage. It
> has just not materialized so far. Life may interfere with digging around.
>
> So, I moved a board over so I could run another 5065 and that way I can
> do other experiments, with the aim to measure deeper on the maser, which
> requires to make the 5065s better if possible. Turns out none of the
> 5065s is having very satisfactory phase-noise, and quick-and-dirty
> attempt to fix that has improved the state, so it seems that it was for
> sure the limiting factor for that 5065.
>
> But that rubidium lamp shall be fixed and that 5065 become operational too.
>
> Cheers,
> Magnus
>
> On 2020-01-15 00:40, paul swed wrote:
> > magnus
> > I was following the thread and it went quiet. Have you been able to make
> > progress on the 5065? Always eager to learn, because one day my 5065 will
> > fail.
> > Regards
> > Paul
> >
> > On Mon, Jan 6, 2020 at 5:04 PM <cdel...@juno.com> wrote:
> >
> >> Magnus,
> >>
> >> If you apply a +20V supply to the lamp connector you should see
> 125-150ma
> >> unlit and it drops  bit when it lights.
> >>
> >> Also measure from the lamp connector center pin to the outside conductor
> >> with an Ohmmeter.
> >>
> >> You should have around 3.33K. The 1.33K resistor (in series with a 2.0K)
> >> is a common problem. it can open up or rise in value.
> >>
> >> I usually replace this resistor in units I service even if it measures
> >> good.
> >>
> >> I use a 1.3K 2% MOX resistor.
> >>
> >> Also check the approx. 12 Ohm resistor on the standoffs to see if it
> >> opened up.
> >>
> >> If  you pull the lamp assy. you can place a spec-A lead and see the RF.
> >> Should be approx 88Mhz. (not critical)
> >>
> >> Once power is applied the lamp  should start (cold) within a minute or
> >> so, warm it starts fast.
> >>
> >> If you place a scope on A7 TP2 and with the lamp assy removed allow some
> >> florescent lighting to fall into the interior you should see a large 50
> >> or 60Hz signal from the light falling on the photocell.
> >>
> >> That is a quick check of the A7!
> >>
> >> Cheers,
> >>
> >> Corby
> >>
> >> Cheers,
> >>
> >> Corby
> >>
> >>
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