If you know the cable connections please POST it to the board. That way, he can check his cable and "fix" it if necessary.
BTW - IS the cable straight through? If so, which conductors are needed?
Cheers!
Bruce
Quoting Lothar baier <Lothar@...>:
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I bought mine on ebay for $800 , spend quite a bit of time trying to figure out the cable
Sent from Mail<> for Windows
From: Bruce via groups.io<mailto:bruce@...>
Sent: Wednesday, March 2, 2022 7:13 PM
To: [email protected]<mailto:[email protected]>
Subject: Re: [HP-Agilent-Keysight-equipment] 8516A cable question
Seems like the wrong wearing due to a cross over or some other
"defect" could cause intermittent operation.
How about using a break out box to look at the signals. I've never
owned an 8516 (owned most of the others). Just looked in my 8510
service manual set and have no 8516 schematic - do have for most of
the others - He could look at the output from the doubler to see if it
is working - possible connector damage is a risk.
Cheers!
Bruce
Quoting Lothar baier <Lothar@...>:
There is no schematic for the 8516 only a few block diagrams , the
switching isn¡¯t done by relays but rather with pin diodes inside the
brick , the doubler control board is buttoned up on the Doubler ,
the only information to be gathered from the service manual is that
there are 4 control lines that go to a PAL that acts as adress
decoder , from there are 5 lines one goes to the doubler to switch
it in and out the other 4 lines go to a block labeled filter control
which outputs 5 lines that go to the actual doubler block so there
is quite a bit of switching going on but there is no info on the
switch points or details on the filters .
Having a crossover cable definatly might be a concern but he also
mentioned that it used to work ¡°intermittent¡± so that¡¯s also
something to think about
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From: Bruce via groups.io<mailto:bruce@...>
Sent: Wednesday, March 2, 2022 6:48 PM
To:
[email protected]<mailto:[email protected]>
Subject: Re: [HP-Agilent-Keysight-equipment] 8516A cable question
Sure but it is comparatively slow - Normal 8510C sweep is relatively
slow, and the problem can be avoided by only weeping 50-20 and say
25-40GHz.
I think the best first step is to look at the doubler switching module
to see if the relay is actually switching the doubler in. I don't
seem to have a schematic diagram for the 8516, but hopefully, HP
included a LED on the module?
In any case need to check the cable connections and determine whether
the doubler is being energized - actually, maybe just watching the +
supply to the doubler itself might work.
Cheers!
Bruce
Quoting Lothar baier <Lothar@...>:
Disagree with you on this, dont forget that the synthesizer is swept
so if you do a 45MHz to 40GHz sweep the doubler is switched in and
out constantly so your DC now becomes a squarewave , also the
control signal not only switches the doubler but also switches in
and out filters to clean up the signal so there is some activity
going on those control lines !
One way to find out would be to tack a scope probe on the control
lines and look at the shape of the control signals
On Mar 2, 2022, at 18:30, Bruce via groups.io
<bruce@...> wrote:
?Missed that - the 20 ft cable seems NOT likely to be a problem -
these ar DC control signals. I recall some discussion that it is a
straight through cable without cross over based on looking at 8341
and 8516 schematic diagrams - I think that I'd focus on
investigating the wiring of the cable.
1) Determine which conductors are used and be certain that the
cable has those conductors 1-1 without cross over.
Cheers!
Bruce
Quoting Lothar baier <Lothar@...>:
He mentioned earlier in this thread that its only 20-40GHz but he
also mentioned using a 20ft cable ? which could be the problem, I
am not sure what the control interface is , the part number of the
control cable says RS232 and there are 4 lines connected in the
testset BUT the doubler control uses a PAL as a decoder so I think
it¡¯s a parallel interface and having a 20ft cable could be a bit
much
Sent from Mail<> for Windows
From: Bruce via groups.io<mailto:bruce@...>
Sent: Wednesday, March 2, 2022 6:21 PM
To:
[email protected]<mailto:[email protected]>
Subject: Re: [HP-Agilent-Keysight-equipment] 8516A cable question
Does the IF error occur below 20 GHz ?? If not, the doubler is
suspect - if so, look at the switching or the test set.
Nexg step would be to try and look at the test set VTO. It is
difficult because they pipe it directly into the samplers.
Cheers!
Bruce
Quoting ratn9ne@...:
Wow you guys are fast to help!
Here is some more info: error is only from 20-40GHz, so it has
something to do with the doubler I assume. Any span or frequency in
this range has this error. I have seen >20GHz work for a little
while but only randomly. My next idea is a shorter DB25 cable as
mine is about 20 feet long. Tried turning up the LO power coming in
on the sweeper with no luck. I can't find a replacement doubler on
ebay to test with. These must be very rare. Can they be serviced?
This display/sweeper/control box setup has been tested with an 8515
and no errors at all.
