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I just purchased a 54645AN scope. The N means it was delivered under a US Navy contract. ?It has a sticker on the back that says it contains a Panasonic BR2354 lithium battery. ?Are they referring the the battery inside the NVRAM or is there a separate standalone battery? ?

Manuel

Thanks Adrian! That helps a lot, my schematics are blurred!

I am a bit confused now, reading the ratings of fuses in A17 and A18 boards from 8566B SA. The current figures are low, specially for the 10 and 5 volt rails, even considering the size of the transformer (it looks bigger than mine). I am lost at this point.?

Maybe the 8566B main transforme could be swapable to my 8350B... but I am not sure, looking only the fuses ratings in both machines (I attached the tables). Maybe the transformer could do the job because overdimension or maybe not. Also depending the way to connect windings can help to feed enought current.

Opinions?

开云体育

There haven't been any modulation changes like those affecting
wwwvb, the inconvenient hiccup when Europe and the UK switched to
9KHz channel spacing for long and medium wave AM broadcasting, and
the shift of the Droitwich frequency from 200 to 198KHz, was the
most significant change, but the Droitwich signal does also carry
phase modulated "teleswitching" data for the energy industry.


I've not noticed any significant effect from this on 198KHz
frequency references, but unlike wwwvb and MSF time and frequency
standards those locked to Droitwich do not generally attempt to
access the time of day signals but just lock to the closely
controlled carrier frequency.

After the frequency change some standards were more easily updated
than others but it seems to have been the kiss of death for the
5090, although that Radcom converter does look to be a potentially
nice solution.


There have been plenty of later designs purpose built for the
198KHz frequency, which is still rubidium locked as far as I know,
but ten or eleven years ago there were reports that the BBC had
bought all the remaining stock of the Droitwich transmitter's
output valves/tubes and was working its way through the last few
pairs.

On that basis I'm pretty sure it should have shut down by now so
perhaps that story wasn't totally accurate after all.

However, aside from that it does seem that a major factor keeping
the 198 KHz transmission alive is the teleswitching data service.
This was previously destined for shut down in 2020 but extended due
to delays in the UK "smart meter" programme with the curent
contract running until the end of March 2023. Whilst no formal
announcements have been made. not that I'm aware of anyway, I've
seen plenty of suggestions that without that extra income there
would be little incentive to keep the 198 KHz service running and
that the BBC may well take the opportunity to shut it down.

It's perhaps not entirely straightforward though as the BBC also
has some contractual coverage obligations, in Scotland for example
that resulted in there being two lower powered 198KHz repeater
stations, still rubidium controlled but not locked to Droitwich or
so closely monitored, which makes traceability more of an issue
anyway as it's not always obvious which transmitter is being
received.

Whatever happens is much more likely to be a political/commercial
decision rather than technical, but I do feel that time is probably
running out for 198KHz frequency standards.

The UK 60KHz cesium referenced time and frequency service, MSF,
which moved north from Rugby to Anthorn around fifteen years ago,
would probably be considered the go to option these days for
broadcast time and frequency references in the UK, with TDF in
France and DCF77 in Germany perhaps being other options, other than
GPS of course.





Also operating from Anthorn we do still have eLoran, experimental
and somewhat unpredictable with no warning of outages these days,
but running most of the time. If or when that signal is
discontinued I'll need to complete my version of your Loran
simulator, but for now it's a case of let's just enjoy that one
while it lasts:-)




Nigel, GM8PZR

Hi Steve
The HP part number is 9100-4603
Regards,
Ruben

Thanks Tony! More clear than mine :D

The manual changes section shows that main transformer (mine is 9100-4603) has a few substitutes depending on the serial: 08350-60064, 9100-4277 and 9100-4337 (this last is the apropiate to my unit S/N 2642A...). It is impossible to get one of those, I only see a -4277 in USA and looks smaller and less-tapped than mine, so it don't match at all.

I located two cheap used transformers in UK: cheapest option is one from an 8566B SA, who has less taps but very powerfull ones (maybe I can use one for make various supplies if it is possible? or add an aditional little transformer I have for the +-15 volt supply); and for twice that money, one from a 8922 GSM analyzer, which has enough secondary windings, but it requires mess up with connections too (I attached a table of outputs of this instrument's power supply for reference). I suppose that feeding the rectifier board with slightly different voltages from transformer?(under certain tolerance)?doesn't affect the final result.

Can anyone send or post a photo of schematics of the main transformer, rectifier and regulator boards in the 8566B manual? Mine (I attached it) is almost not readable and I need those figures to decide which transformer I'll buy. Thanks in advance.

So maybe this adventure will continue.

Every opinion or advice is welcome, honestly. I'm here to learn :)

Regards,
Ruben