EMRFD Message Archive 7764

Message Date From Subject
7764 2012-09-10 09:40:10 Ashhar Farhan tektronix 465M vs Rigol
this is probably off-topic, but i supp that there are many 465 veterans
here, so with due apologies...

first, i am not even sure if i should be considering another scope. but
tektronix 465 that i already have is behaving strangely. i have a pair of
P6105 probes. most of them time, when i clip the ground lead to a pcb and
touch the tip to the ground of the PCB. it shows fairly high level of AC.
the AC, at times suddenly vanishes. Then, at times I see a damped
oscillation of a very low frequency overlaid on the signal that i am seeing
(This happens only if i adjust the trigger very carefully). These happen
even though the PCB is entirely isolated. then if i fool around with the
BNC connector it often goes away. but not always. this is also happening on
the second channel that is connected to my 50 ohms termination load and a
cable to measure 50 ohms outputs. i have unscrewed the bnc connectors of
the P6105 probes, resoldered the 10x attentuators, WD40-ed them, and
general spend some quality time .. i suspect that the problem is at the tip
end of the probe, not the 'scope connector end. can someone help?

i would like to retain the 465 of course. it also helps me see
(uncaliberated though) up to 200 MHz. there is nothing like the tek's
smooth controls and the works. i have recently caliberated the scope, so it
is in pretty good shape .. on a clear day.

on the other hand, i have heard lot of good things about the rigol 1052e.
but i am not sure what happens if we feed a signal above 50 MHz (like a
145MHz signal). will it anti-alias itself down to a lower frequency? why is
the bandwidth treated as 50M, when the sampling is at 1Gig? surely,
sampling frequency can be as low as 5 times the signal frequency and it
still gets good fidelity. does this mean that rigol will work at higher
bandwidths, with lesser resolution or will the anti-aliasing police eat up
the higher frequencies?

right now, there is a sale on the Rigol in India, it ends on september
30th. but i don't really need the rigol if the 465 problem is resolved.

- farhan


[Non-text portions of this message have been removed]
7765 2012-09-10 13:31:02 Lasse Moell Re: tektronix 465M vs Rigol
A digital scope is a great companion to your ageing analogue one!
Rigol seems to be a favourite amongst hobbyists, and it seems to be
upgradable by
loading new firmware and give you twice the bandwith!!! Google is your
friend!

It seems that Agilent/Tektronix/LeCroy are made in the very same
factories that produces scopes with names like Rigol... so I bet the
quality is not bad!

Still, there are lots of signals that can turn your head inside out
using a digital scope, so use it wice!
I find a digital scope great for my digital signal troubble shooting,
and the feature to transfer data and images to PC is really handy.
But I would not replace a good analogue scope with a low-end digital
scope, but that is me :)

/Lasse SM5GLC

Ashhar Farhan skrev 2012-09-10 18:40:
>
> this is probably off-topic, but i supp that there are many 465 veterans
> here, so with due apologies...
>
> first, i am not even sure if i should be considering another scope. but
> tektronix 465 that i already have is behaving strangely. i have a pair of
> P6105 probes. most of them time, when i clip the ground lead to a pcb and
> touch the tip to the ground of the PCB. it shows fairly high level of AC.
> the AC, at times suddenly vanishes. Then, at times I see a damped
> oscillation of a very low frequency overlaid on the signal that i am
> seeing
> (This happens only if i adjust the trigger very carefully). These happen
> even though the PCB is entirely isolated. then if i fool around with the
> BNC connector it often goes away. but not always. this is also
> happening on
> the second channel that is connected to my 50 ohms termination load and a
> cable to measure 50 ohms outputs. i have unscrewed the bnc connectors of
> the P6105 probes, resoldered the 10x attentuators, WD40-ed them, and
> general spend some quality time .. i suspect that the problem is at
> the tip
> end of the probe, not the 'scope connector end. can someone help?
>
> i would like to retain the 465 of course. it also helps me see
> (uncaliberated though) up to 200 MHz. there is nothing like the tek's
> smooth controls and the works. i have recently caliberated the scope,
> so it
> is in pretty good shape .. on a clear day.
>
> on the other hand, i have heard lot of good things about the rigol 1052e.
> but i am not sure what happens if we feed a signal above 50 MHz (like a
> 145MHz signal). will it anti-alias itself down to a lower frequency?
> why is
> the bandwidth treated as 50M, when the sampling is at 1Gig? surely,
> sampling frequency can be as low as 5 times the signal frequency and it
> still gets good fidelity. does this mean that rigol will work at higher
> bandwidths, with lesser resolution or will the anti-aliasing police eat up
> the higher frequencies?
>
> right now, there is a sale on the Rigol in India, it ends on september
> 30th. but i don't really need the rigol if the 465 problem is resolved.
>
> - farhan
>
> [Non-text portions of this message have been removed]
>
>
7766 2012-09-10 13:55:26 pat bunn Re: tektronix 465M vs Rigol
The 465 is not just losing calibration when you are looking at those 200
Mhz signals. It is lying to you. Doing the same thing as filtering it
with a low pass filter.

When I first got my 400 Mhz scope - It scared me!

I couldn't believed what I had been missing when looking at 1 mHz signals.

Pat
N4LTA



n 9/10/2012 4:30 PM, Lasse Moell wrote:
> A digital scope is a great companion to your ageing analogue one!
> Rigol seems to be a favourite amongst hobbyists, and it seems to be
> upgradable by
> loading new firmware and give you twice the bandwith!!! Google is your
> friend!
>
> It seems that Agilent/Tektronix/LeCroy are made in the very same
> factories that produces scopes with names like Rigol... so I bet the
> quality is not bad!
>
> Still, there are lots of signals that can turn your head inside out
> using a digital scope, so use it wice!
> I find a digital scope great for my digital signal troubble shooting,
> and the feature to transfer data and images to PC is really handy.
> But I would not replace a good analogue scope with a low-end digital
> scope, but that is me :)
>
> /Lasse SM5GLC
>
> Ashhar Farhan skrev 2012-09-10 18:40:
>> this is probably off-topic, but i supp that there are many 465 veterans
>> here, so with due apologies...
>>
>> first, i am not even sure if i should be considering another scope. but
>> tektronix 465 that i already have is behaving strangely. i have a pair of
>> P6105 probes. most of them time, when i clip the ground lead to a pcb and
>> touch the tip to the ground of the PCB. it shows fairly high level of AC.
>> the AC, at times suddenly vanishes. Then, at times I see a damped
>> oscillation of a very low frequency overlaid on the signal that i am
>> seeing
>> (This happens only if i adjust the trigger very carefully). These happen
>> even though the PCB is entirely isolated. then if i fool around with the
>> BNC connector it often goes away. but not always. this is also
>> happening on
>> the second channel that is connected to my 50 ohms termination load and a
>> cable to measure 50 ohms outputs. i have unscrewed the bnc connectors of
>> the P6105 probes, resoldered the 10x attentuators, WD40-ed them, and
>> general spend some quality time .. i suspect that the problem is at
>> the tip
>> end of the probe, not the 'scope connector end. can someone help?
>>
>> i would like to retain the 465 of course. it also helps me see
>> (uncaliberated though) up to 200 MHz. there is nothing like the tek's
>> smooth controls and the works. i have recently caliberated the scope,
>> so it
>> is in pretty good shape .. on a clear day.
>>
>> on the other hand, i have heard lot of good things about the rigol 1052e.
>> but i am not sure what happens if we feed a signal above 50 MHz (like a
>> 145MHz signal). will it anti-alias itself down to a lower frequency?
>> why is
>> the bandwidth treated as 50M, when the sampling is at 1Gig? surely,
>> sampling frequency can be as low as 5 times the signal frequency and it
>> still gets good fidelity. does this mean that rigol will work at higher
>> bandwidths, with lesser resolution or will the anti-aliasing police eat up
>> the higher frequencies?
>>
>> right now, there is a sale on the Rigol in India, it ends on september
>> 30th. but i don't really need the rigol if the 465 problem is resolved.
>>
>> - farhan
>>
>> [Non-text portions of this message have been removed]
>>
>>
>
>
>
> ------------------------------------
>
> Yahoo! Groups Links
>
>
>
>
7768 2012-09-10 17:35:56 Russell Shaw Re: tektronix 465M vs Rigol
7769 2012-09-10 19:21:31 AD7ZU Re: tektronix 465M vs Rigol
It seems odd that you would suddenly have 2 bad probes!
a more likely scenerio is the internal ground connection between the probe socket and the input amp is intermittent.  that connection is likely a common connection to both probes.
 
I have seen connectors become loose or corroded
7770 2012-09-10 20:34:45 Reginald Beardsle... Re: tektronix 465M vs Rigol
I have a 465 which I'm afraid to turn on because it will only make me unhappy if I do. I bought a Rigol for that reason.

The 465 is socketed transistors w/ the consequence that they are troublesome in old age. I bought mine semi-functional and spent lots of time repairing problems including several bad solder joints. I strongly suspect that your problems are inside the Tek and to fix them you need a scope, a manual and a large measure of patience. I've also repaired a Dumont 1062 which is a 60 MHz dual trace scope of the same vintage and technology as the 465. It also had problems w/ corroded transistor leads and bad solder joints.

BTW Do NOT spray tuner cleaner on the switches! It's bad for the capacitors in the input section.

Something I learned from a retired Tek technician is whacking the scope front frame w/ a piece of wood or both hands, one on each side, to determine if problem is an intermittent. Freaked me out when I watched him, but later I realized it made good sense. Just be careful of where you hit.

I bought the DS-1102E for $400 US which I thought an excellent deal. I've not used it a lot yet and have no experience other than w/ analog scopes, so it's a bit odd to deal w/ at times. In general I'm happy w/ it. It's quite nicely made. I feel confident that any issues are user error. I'm analog, but the scope is digital.

There's a lot of stuff on the web about hacking the firmware to "convert" a 1052E to an 1102E, however, none of the people I've seen write about doing that had the means to accurately check the results. My guess is that Rigol builds the scopes and then tests them. The ones that don't meet the higher spec get a DS1052E label and the ones that do get a DS1102E label. The vertical sections of scopes are rather exotic and delicate, primarily because of the need to accept signals over a wide range.

The rise time on a 465 is spec'd at under 1 nS and I suspect that that's why the Rigol and other DSOs have a sample rate which is ~10x the bandwidth. Without the high sample rate, a DSO would not present the same graph as an analog scope which is certainly what a user would expect.

Hope this helps. I think you'll find it a worthwhile adjunct to the 465. The Rigol has the ability to capture 1 million samples which can be downloaded via USB to a computer.

Have Fun!
Reg
7771 2012-09-10 20:34:52 rlramirez77 Re: tektronix 465M vs Rigol
I have not used a 465 since college, but I've been keeping an eye
7772 2012-09-10 20:54:52 Ashhar Farhan Re: tektronix 465M vs Rigol
Thanks all,

I will try fixing the 465. It is a superb instrument and it has worn well
with experience to the point that i operate it intuitively. i guess i will
skip on the rigol for the time being.

- farhan