Re: Dynamic Characteristics
In case anyone is interested, Radiotron Designer's Handbook as usual has all the answers already.
Jaz
|
Re: Need help choosing a scope and some other RF capable equipment.
Hi Don,
I really enjoy the group. Thanks.
Jerry Massengale
toggle quoted message
Show quoted text
-----Original Message-----
From: Don Black
To: TekScopes
Sent: Fri, Jan 4, 2013 5:33 pm
Subject: Re: [TekScopes] Need help choosing a scope and some other RF capable equipment.
?
Hi jerry,
??? ??? ????? I'm in Australia, shipping costs here would be much
more than the scope. It looks like a nice package, I'm sure it will
sell.
I always enjoy your posts to the group, usually learn something from
them.
Don Black.
On 05-Jan-13 10:24 AM, jerry massengale wrote:
?
Thanks Don,
Yes it is 200MHZ. I will see if I can
fix the listing. Where are you?
Jerry Massengale
-----Original
Message-----
From: Don Black
To: TekScopes
Sent: Fri, Jan 4, 2013 4:08 pm
Subject: Re: [TekScopes] Need help choosing a scope
and some other RF capable equipment.
?
Hi Jerry,
??? ??? ??? ??? Nice looking scope, too
far away for me. However, you've listed it
as a 200 MHz scope in the title but only
100 MHz in the description. I guess I
could look it up but which is correct? I
suspect 200 MHz.
Don Black.
On 05-Jan-13 5:03 AM, jerry massengale
wrote:
?
Hi,
Sounds like Hybrid battery work. There are
several nice 475s on ebay.
Just search for tektronix 475.
If you like, I have a 3
channel 7704A on ebay. See item 290839243077.
It should serve
well and other options can
be added.
Jerry Massengale
-----Original
Message-----
From: sknaugler
To: TekScopes
Sent: Fri, Jan 4, 2013 10:34 am
Subject: [TekScopes] Need help
choosing a scope and some other RF
capable equipment.
?
Sorry, this is long.
Maybe you folks can help
with our project, point us
to sources of RF help, or at
least help me find a scope.
But because this is a scope
forum I'll start with the
scope part. I should add
that a DSO would be nice,
but an old fashioned CRT
analog scope may be
perfectly fine.
We need a scope to examine a
waveform that we want to
apply to a pair of
electro-chemical cells wired
in series. Currently we
power the cells with 1.0
VDC, and they normally they
draw between 3 and 5 A. It
is thought that cell
performance would improve if
we can cause the chemicals
in the cells to resonate,
hence the desire to
superimpose an AC signal on
top of the DC. We have been
able to explore frequencies
up to 100 kHz for square
waves and pulses and 300 kHz
for sine waves, but not
surprisingly those lowish
frequencies did not help.
We now want to explore
frequencies from about 1 MHz
to as much as we can afford
on a shoestring budget, but
no less than 30 MHz for
square waves and pulses and
50 MHz for sine waves. 100
MHz would be nice, but
there's that budget issue.
The waveforms, at least
initially, would be limited
to 1 V maximum, and never
going negative. We are
thinking that the maximum AC
amplitude would be 0.5 V
peak, or 1.0 V peak to peak,
and that would be
superimposed on a 0.5 V DC
bias voltage. A minimum AC
amplitude would be 0.05 V
peak, or 0.10 V peak to
peak, and that would be
superimposed on a 0.95 DC
bias voltage.
We'd also like to monitor
current if we can find a
shunt that does not distort
the waveform.
An issue is that I can't
guarantee that the final
wiring will give us a common
ground point so we may need
a scope and lead set up
where can can measure two
differential voltages. (Our
Tek 222 with it's isolated
inputs is nice in that
regard, but at 10 MHz
bandwidth won't work for
these higher frequencies.)
So if you guys can point us
in the right direction for
what models of new or used
scopes might work for us. Or
even sell us one of your
surplus working scopes.
Local Craiglist scopes
available that appear to
work from pics and
description: (I know, buyer
beware.)
Tek 2465 (not A or B) $350
firm. (Seems a little high)
Tek 2215A, $100 firm (Not
quite enough bandwidth)
Tek TDS 3052B (No price
given, and I don't know much
about this other than
labeled 500 MHz)
Anritsu MS2711D (I know
nothing about this brand or
model)
We're also going to need an
arbitrary waveform
generator, and the
"superimposed RF on top of
DC" power supply. These
could be the subject of
another posting if there's
any interest, or we could
keep those non scope
subjects off forum.
If it makes any difference,
our 3 person start up is in
Seaford, Delaware.
|
Re: 2246 Mod A main board overloading the SMPS
Tom,
I was only able to get enough time to assemble the SMPS into the chassis with just the main board and it runs fine - without the 40W series bulb:). The voltages are a bit off (5.28V, 7.46V etc) but I won't adjust anything till the proc board and the pot boards are in and providing normal operating load.
That's for the weekend. More to come.
Thanks for taking the time to make resistance measurements - very similar to mine.
Priya.
toggle quoted message
Show quoted text
--- In TekScopes@..., "Tom Jobe" wrote:
Hi Priya,
Resistances were taken on a nice working 2246 with a Fluke 110 which does not have enough voltage to forward bias the diodes.
I tried this Fluke meter on some standard diodes and some Schottky diodes and there was not much of a connection either way, just a little leakage depending on the polarity
There is not much difference from your readings, and no obvious indication of a problem on any of the voltages.
I will add my readings on to the end of your list.
+5:100 ?? - mine is 99 ohm - 106 ohm
-5:50 ?? - mine is 41 ohm - 53 ohm
-15:500 ?? - mine is 750 ohm - 590 ohm
+15:400 ?? - mine is 583 ohm - 483 ohm
+7.5:150 ?? - mine is 134 ohm - 152 ohm
-7.5:180 ?? - mine is 143 ohm - 150 ohm
+58: 7500 ?? - mine is almost open ( 8M ohm) - 2.5 M ohm? impossible to get a good reading
+130: 9000 ?? - mine is 10,000 - 9000 ohm I guess the next step is to see what happens when you put the scope back together tonight.
tom jobe...
----- Original Message -----
From: Mover
To: TekScopes@...
Sent: Friday, January 04, 2013 12:20 PM
Subject: [TekScopes] Re: 2246 Mod A main board overloading the SMPS
Tom & Francis,
I discovered what it is - the ultra cautious in me had left a 40W light bulb in series with the isolation transformer secondary providing AC line power to the scope. It was there originally to prevent further collateral damage to the scope through my repair and testing. With any load exceeding the load provided by the fan, the SMPS pulls enough current through the light bulb that the AC line power to the scope drops below the 80V required to keep the SMPS running. This shuts down the SMPS and the 40W bulb comes on as the SMPS restarts - absolutely normal behavior. I had completely forgotten about the light bulb till this afternoon when I chanced to glance at it cycling with the SMPS and then I had an AHA moment!
Regardless, I did measure resistances (with a Fluke 116 - don't own a meter recommended by TEK) and here they are:
> +5:100 ?? - mine is 99 ohm
> -5:50 ?? - mine is 41 ohm
> -15:500 ?? - mine is 750 ohm
> +15:400 ?? - mine is 583 ohm
> +7.5:150 ?? - mine is 134 ohm
> -7.5:180 ?? - mine is 143 ohm
> +58: 7500 ?? - mine is almost open ( 8M ohm)
> +130: 9000 ?? - mine is 10,000
Other than the 58V resistance probably becuase my meter can't drive the diodes, my measurements looks fine.
I ran it without the series light bulb and it happily drives a 10 ohm resistor from the 5V and regulation is excellent at 5.05 VDC. With the light bulb in series, it won't run anything more than the fan. Indeed, the fan is not sufficient load to test the SMPS.
Believe I am ready to put the SMPS back into the scope tonight. I apologize to everyone who I misled with my earlier post on this and thanks as always for quick and thoughtful responses. You guys are great!
Priya.
--- In TekScopes@..., "Francis" wrote:
>
> Hi,
>
> several things:
>
> as Tom Jobe suggested, you can do the following:
> with the scope disconnected from the mains, check the resistances
> between ground and each supply. As Tek says, use an ohmeter that is able to forward bias diodes, usually a low range.
>
> Values are
> +5:100 ??
> -5:50 ??
> -15:500 ??
> +15:400 ??
> +7.5:150 ??
> -7.5:180 ??
> +58: 7500 ??
> +130: 9000 ??
>
> these values are taken from a 2245A manual, but should not be
> very different on your scope. If one is significantly lower,
> check the related circuitry.
>
> The fan is not a sufficient load for the SMPS. When I make
> my trials, I use 2 4.7 ?? paralleled on the +5v.
> If the supply still ticks, try to disconnect the crowbar protection,
> or tie together the gate and the cathode of the SCR. Maybe some
> overvoltage due to a dying cap can fire it. Same recommendation
> about Q2208 (base tied to ground).
>
> --- In TekScopes@..., "Mover" wrote:
> >
> > Alas - if only it were that simple ...
> >
> > I finally fixed my SMPS and put it back into the chassis with only the main board. It runs in chirp mode - about every 1 sec there is a clicking sound - the secondary voltages rise and then something gets overloaded and the SMPS shuts down and then cycles again.
> >
> > I quickly disconnected power, isolated the SMPS and again verified that the SMPS is fine on its own with just the cooling fan load with a steady internal 44 VDC. No new or collateral damage thankfully.
> >
> > There are no obvious shorts on any of the supply lines on the main board. The issue may still very well be with the SMPS being unable to handle load even though the fan runs fine and the other voltages are fine.
> >
> > I assume that chirp mode is a common issue with these SMPS supplies. What have others done to (1) find whether the issue is with the SMPS or with the main board and if the latter, (2) which supply line or lines is drawing too much current and how to isolate the problem further?
> >
> > Thanks in advance.
> >
> > Priya.
> >
>
|
Re: Need help choosing a scope and some other RF capable equipment.
David,
A bias tee isn't a big deal at all, but injecting the properly biased RF voltage with the DC and RF currents at workable voltages/currents might be.
I
think it's an interesting project, from a standpoint of "how do we do this" -- based on their three-person, self-funded, bootstrapped startup paradigm.
Even if the project fails, helping develop the technology might be fun for many of us.
From my computer? ?This looks like as
interesting a challenge as helping the neighbor across the backyard fence rebuild his fence to keep his daughter's pit bulldog confined -- neighbor knew less than nothing about fence-building, but we shared a common vision.
We succeeded, and we accomplished our shared vision of fixing the fence to keep that G%^&D*(%%$(&^)* mutt confined.
I would hope that all of us would see this particular project from the same standpoint -- achieve success, or at least experience failure at the peak of our shared technical abilities. ?
I hesitate to list my projects that I've started but that failed on the first endeavor. ? Most of you should have a similar record of failure -- if you don't, then you're not looking high enough nor reaching far enough.
73 Jim N6OTQ
From: David DiGiacomo
To: TekScopes@...
Sent: Friday, January 4, 2013 5:49 PM
Subject: Re: [TekScopes] Re: Need help choosing a scope and some other RF capable equipment. A bias tee is not a big deal.
|
Re: Cleaning Tek475A Attenuator Switches
Great job.
I did the same thing on my 465 after several months of erratic behavior and several cleanups of contacts. In the end I decided to try the chance, took off modules attenuators, took off their caps and remade with the utmost care all the solderings on the pins.
I'm short-sighted so I can see very well close.
The procedure was finally decisive. Never again I had problems with the attenuators.
Max
|
Re: what is the differences between 465 and 465B?
On 01/04/2013 06:48 PM, Matt Jodz
wrote:
?
Another newbie question and let me say thanks for the
groups patience beforehand!!? I have been trying to
research the differences between the Tek 465 and 465B
scopes.? Can I use the 465 Service Manual on the 465B or
must I get the 465B service manual?? I have only been
able to find an internet comment that the B was an
improved 465 and that it is preferred.? Is that because
it is a newer design/model or is there some better
capability in the B over the plain jane 465?? Can
anybody enlighten me?? Thanks.
There is a nice article in one of the Tekscopes flyers which covers
the updates.
If nobody else gets it in the next few hours, I'll see if I can find
it and attach it to a new message.
I have a high-mileage 465B ( among many others )... it just seems to
go on forever.
Never had a 465 but have used them in at least ten different
countries.
They were very much the goto scope for the early computer industry.
There is a free PDF for the 'B' on the web.
|
Re: Which would you pick? 454 or 475?
It is funny you should mention that. I told someone on the funwithtubes list that the warm up drift he complained about in the 454 was expected because its Nuvistor based vertical amplifiers are not temperature compensated unlike the later 454A dual FET vertical amplifiers. My CA amplifier is pretty drifty as well but it is not temperature compensated either. On Fri, 4 Jan 2013 17:04:56 -0700, David DiGiacomo <daviddigiacomo@...> wrote: The 475 is definitely a better scope, but... I really enjoy using the
454. The sharp trace is very, very nice. The thing I like least
about it is the DC drift/unstable attenuator balance. You end up
tweaking the vertical position quite a bit.
I wouldn't say either model is particularly reliable or fun to fix.
|
Re: 2246 Mod A main board overloading the SMPS
Hi Priya,
Resistances were taken on a nice working 2246 with a Fluke 110
which does not have enough voltage to forward bias the diodes.
I tried this Fluke meter on some standard diodes and some
Schottky diodes and there was not much of a connection either
way,?just?a little?leakage?depending on
the?polarity
There is not much difference from your readings, and
no?obvious indication of a problem on any of the voltages.
I will add my readings on to the end of your
list.
?
> +5:100 ?? - mine is 99 ohm????-???
106 ohm
> -5:50 ?? - mine is 41 ohm??? -???
53 ohm
> -15:500 ?? - mine is 750 ohm???
-??? 590 ohm
> +15:400 ?? - mine is 583
ohm??? -??? 483 ohm
> +7.5:150 ?? - mine is
134 ohm??? -??? 152 ohm
> -7.5:180 ?? - mine
is 143 ohm??? -??? 150 ohm
> +58: 7500 ?? -
mine is almost open ( 8M ohm)??? -??? 2.5 M
ohm??impossible to get a good reading
> +130: 9000 ?? - mine is
10,000??? -??? 9000 ohm
?
I guess the next step is to see what happens when you put the
scope back together tonight.
tom jobe...
?
toggle quoted message
Show quoted text
----- Original Message -----
Sent: Friday, January 04, 2013 12:20
PM
Subject: [TekScopes] Re: 2246 Mod A main
board overloading the SMPS
?
Tom & Francis,
I discovered what it is - the ultra cautious in
me had left a 40W light bulb in series with the isolation transformer
secondary providing AC line power to the scope. It was there originally to
prevent further collateral damage to the scope through my repair and testing.
With any load exceeding the load provided by the fan, the SMPS pulls enough
current through the light bulb that the AC line power to the scope drops below
the 80V required to keep the SMPS running. This shuts down the SMPS and the
40W bulb comes on as the SMPS restarts - absolutely normal behavior. I had
completely forgotten about the light bulb till this afternoon when I chanced
to glance at it cycling with the SMPS and then I had an AHA moment!
Regardless, I did measure resistances (with a Fluke 116 - don't own a
meter recommended by TEK) and here they are:
> +5:100 ?? - mine is 99
ohm
> -5:50 ?? - mine is 41 ohm
> -15:500 ?? - mine is 750
ohm
> +15:400 ?? - mine is 583 ohm
> +7.5:150 ?? - mine is 134
ohm
> -7.5:180 ?? - mine is 143 ohm
> +58: 7500 ?? - mine is
almost open ( 8M ohm)
> +130: 9000 ?? - mine is 10,000
Other than
the 58V resistance probably becuase my meter can't drive the diodes, my
measurements looks fine.
I ran it without the series light bulb and it
happily drives a 10 ohm resistor from the 5V and regulation is excellent at
5.05 VDC. With the light bulb in series, it won't run anything more than the
fan. Indeed, the fan is not sufficient load to test the SMPS.
Believe I
am ready to put the SMPS back into the scope tonight. I apologize to everyone
who I misled with my earlier post on this and thanks as always for quick and
thoughtful responses. You guys are great!
Priya.
--- In TekScopes@...,
"Francis" wrote:
>
> Hi,
>
> several things:
>
> as Tom Jobe suggested, you can do the following:
> with the
scope disconnected from the mains, check the resistances
> between
ground and each supply. As Tek says, use an ohmeter that is able to forward
bias diodes, usually a low range.
>
> Values are
> +5:100
??
> -5:50 ??
> -15:500 ??
> +15:400 ??
> +7.5:150
??
> -7.5:180 ??
> +58: 7500 ??
> +130: 9000 ??
>
> these values are taken from a 2245A manual, but should not be
> very different on your scope. If one is significantly lower,
>
check the related circuitry.
>
> The fan is not a sufficient load
for the SMPS. When I make
> my trials, I use 2 4.7 ?? paralleled on the
+5v.
> If the supply still ticks, try to disconnect the crowbar
protection,
> or tie together the gate and the cathode of the SCR. Maybe
some
> overvoltage due to a dying cap can fire it. Same recommendation
> about Q2208 (base tied to ground).
>
> --- In TekScopes@...,
"Mover" wrote:
> >
> > Alas - if only it were that simple
...
> >
> > I finally fixed my SMPS and put it back into
the chassis with only the main board. It runs in chirp mode - about every 1
sec there is a clicking sound - the secondary voltages rise and then something
gets overloaded and the SMPS shuts down and then cycles again.
> >
> > I quickly disconnected power, isolated the SMPS and again
verified that the SMPS is fine on its own with just the cooling fan load with
a steady internal 44 VDC. No new or collateral damage thankfully.
> >
> > There are no obvious shorts on any of the supply lines on the
main board. The issue may still very well be with the SMPS being unable to
handle load even though the fan runs fine and the other voltages are
fine.
> >
> > I assume that chirp mode is a common issue
with these SMPS supplies. What have others done to (1) find whether the issue
is with the SMPS or with the main board and if the latter, (2) which supply
line or lines is drawing too much current and how to isolate the problem
further?
> >
> > Thanks in advance.
> >
>
> Priya.
> >
>
|
Re: Need help choosing a scope and some other RF capable equipment.
Only Kansas and my high-school girlfriends are flat.
:)
73 Jim N6OTQ
From: Don Black
To: TekScopes@...
Sent: Friday, January 4, 2013 4:58 PM
Subject: Re: [TekScopes] Need help choosing a scope and some other RF capable equipment.
You mean it really isn't flat???
Don Black.
On 05-Jan-13 9:24 AM, Jim wrote:
?
History
teaches us the unfortunate lessons and fates of people
who believed that a flat Earth was the center of the
Universe.
73
Jim
N6OTQ
|
Could be. Admittedly all the functionality I have observed is at room temperature here in southern Louisiana. I can but assume they would/may turn quite a bit more brittle at subzero temperatures.(which I hopefully never have to experience * smile *) ?
toggle quoted message
Show quoted text
From: TekScopes@... [mailto:TekScopes@...] On Behalf Of John Griessen
Sent: Friday, January 04, 2013 8:30 AM
To: TekScopes@...
Subject: Re: [TekScopes] Re: Rear feet for 475? ?
Sounds like ABS -- it has some flex and does not shatter easily, (maybe if in Alaska winter).
|
Re: High Voltage Probe to work on Scopes.
Yes, Craig is right. I only use it on a scope for < 100Hz stuff and
if I'm *really* desperate since I don't have a better performing high voltage probe. Neil
www.gruending.net 05/01/2013 00:15 So they would be OK to look for ripple on a 5kV plate supply I have made? -- Best Regards, Chris Wilson.
|
Re: Which would you pick? 454 or 475?
The 475 is definitely a better scope, but... I really enjoy using the
454. The sharp trace is very, very nice. The thing I like least
about it is the DC drift/unstable attenuator balance. You end up
tweaking the vertical position quite a bit.
I wouldn't say either model is particularly reliable or fun to fix.
|
Re: High Voltage Probe to work on Scopes.
Yes, Craig is right. I only use it on a scope for < 100Hz stuff and if I'm *really* desperate since I don't have a better performing high voltage probe.
Neil
On Fri, Jan 4, 2013 at 3:55 PM, Craig Sawyers <c.sawyers@...> wrote:
?
======================
I guess this is the graph, found by Google search
>. It's
valuable to know what's really happening.
Looking at the SA graph and comparing to the table, it seems to show a big
falloff by 100 Hz, while the table only shows about 2% drop. Is this due to
some artifact of the SA or am I misreading it (likely). The scale indicates
start 0Hz, stop 1000 Hz which is 100 Hz per division.
======================
The AC spec of the probe in the manual is only quoted at 60Hz, which is
+/-5%. So look upon this as essentially a DC probe.
Craig
|
Re: what is the differences between 465 and 465B?
There are major differences between the models.? The service manual won't work for both.
I have both (although the 465B is a parts unit) and the differences are so much that it's not possible to interchange much.? I was able to move the fan from the B to the other but I can't even move over the lamps for the vertical sensitivity because they are incandescent in the 465 and LED in the B.? The delay line is the same I think, but there are many differences.
Bob
|
--- On Fri, 1/4/13, Matt Jodz wrote:
From: Matt Jodz
Subject: [TekScopes] what is the differences between 465 and 465B?
To: "TekScopes@..."
Date: Friday, January 4, 2013, 3:48 PM
?
Another newbie question and let me say thanks for the groups patience beforehand!!? I have been trying to research the differences between the Tek 465 and 465B scopes.? Can I use the 465 Service Manual on the 465B or must I get the 465B service manual?? I have only been able to find an internet comment that the B was an improved 465 and that it is preferred.? Is that because it is a newer design/model or is there some better capability in the B over the plain jane 465?? Can anybody enlighten me?? Thanks.
|
Re: High Voltage Probe to work on Scopes. [1 Attachment]
======================
I guess this is the graph, found by Google search
<>. It's
valuable to know what's really happening.
Looking at the SA graph and comparing to the table, it seems to show a big
falloff by 100 Hz, while the table only shows about 2% drop. Is this due to
some artifact of the SA or am I misreading it (likely). The scale indicates
start 0Hz, stop 1000 Hz which is 100 Hz per division.
======================
The AC spec of the probe in the manual is only quoted at 60Hz, which is
+/-5%. So look upon this as essentially a DC probe.
Craig
|
Re: Need help choosing a scope and some other RF capable equipment.
"Bound water and ice have critical frequencies (??S) at about 10 MHz"
The above quote is from: That is not resonance. We believe the water in our cells ins "bound" and not free, hence our desire for a DC biased RF power supply, but we need to test this. We really hope that the water is not free because we really don't want to deal with DC biased microwave power supplies. A bias tee is not a big deal.
|
what is the differences between 465 and 465B?
Another newbie question and let me say thanks for the groups patience beforehand!!? I have been trying to research the differences between the Tek 465 and 465B scopes.? Can I use the 465 Service Manual on the 465B or must I get the 465B service manual?? I have only been able to find an internet comment that the B was an improved 465 and that it is preferred.? Is that because it is a newer design/model or is there some better capability in the B over the plain jane 465?? Can anybody enlighten me?? Thanks.
|
Re: 2246 Mod A main board overloading the SMPS
Completely agree. I ran the SMPS with just the fan for a whole afternoon before I was willing to go further.
With the 40W series bulb removed :), the SMPS starts up correctly with just the SMPS and the main board. The voltages are a bit off but I don't want to adjust the +7.5V till all the boards are in and the SMPS is running under full load.
More to come.
Priya.
toggle quoted message
Show quoted text
--- In TekScopes@..., "chipbee40" wrote:
--- In TekScopes@..., "Mover" wrote:
Indeed, the fan is not sufficient load to test the SMPS.
In my post in the original thread I was not implying that the fan alone was sufficient to "test" the power supply, merely that in order to fault find on a non working/tripping supply it was a convenient load/indicator of the power supply ability to function. Some switching supplies will not run without a certain load, this one will run with just the fan attached. Most faults can be rectified just with the fan as an indication. Unfortunately Tektronix omitted power supply expected load information, unlike Philips/Fluke for which scopes I have built full load test boards. JC
|
Re: Which would you pick? 454 or 475? -->the 475!!!
realistically, the 475 is just a better scope in every way, and significantly newer and better desgined. and you have to love the 200+MHz bandwidth, and the ability to stop it down for lower frequency work. however, check the serial number, if low (below 20K), it may be a bit of a toss up. but power it up, see if it works, and check that the controls are not intermittent or noisy. a bit of de-oxit will improve the pushbutton switches. check the power supply caps, they are usually in need of replacements, and newer ordinary 105C radials work just fine there, as long as you remember to jumper the old style FP electrolytic ground pads together. the 454 will be much harder to get and keep running. the 475 custom ICs are generally available, the TD's not so much (in the trigger).
all the best,
walter
sphere research corp.
toggle quoted message
Show quoted text
--- In TekScopes@..., Matt Jodz wrote:
Looking at getting either a 454 or a 475 and would appreciate any opinions as to reliability and ease of maintenance and repair for these two scopes.? The 454 is working fine and the 475 needs some (hopefully) minor repair.? I will be using them for hobby repair of older radio and test equipment.? Which would you prefer?? Thanks.
|
Re: Need help choosing a scope and some other RF capable equipment.
Hi jerry,
??? ??? ????? I'm in Australia, shipping costs here would be much
more than the scope. It looks like a nice package, I'm sure it will
sell.
I always enjoy your posts to the group, usually learn something from
them.
Don Black.
On 05-Jan-13 10:24 AM, jerry massengale wrote:
toggle quoted message
Show quoted text
?
Thanks Don,
Yes it is 200MHZ. I will see if I can
fix the listing. Where are you?
Jerry Massengale
-----Original
Message-----
From: Don Black
To: TekScopes
Sent: Fri, Jan 4, 2013 4:08 pm
Subject: Re: [TekScopes] Need help choosing a scope
and some other RF capable equipment.
?
Hi Jerry,
??? ??? ??? ??? Nice looking scope, too
far away for me. However, you've listed it
as a 200 MHz scope in the title but only
100 MHz in the description. I guess I
could look it up but which is correct? I
suspect 200 MHz.
Don Black.
On 05-Jan-13 5:03 AM, jerry massengale
wrote:
?
Hi,
Sounds like Hybrid battery work. There are
several nice 475s on ebay.
Just search for tektronix 475.
If you like, I have a 3
channel 7704A on ebay. See item 290839243077.
It should serve
well and other options can
be added.
Jerry Massengale
-----Original
Message-----
From: sknaugler
To: TekScopes
Sent: Fri, Jan 4, 2013 10:34 am
Subject: [TekScopes] Need help
choosing a scope and some other RF
capable equipment.
?
Sorry, this is long.
Maybe you folks can help
with our project, point us
to sources of RF help, or at
least help me find a scope.
But because this is a scope
forum I'll start with the
scope part. I should add
that a DSO would be nice,
but an old fashioned CRT
analog scope may be
perfectly fine.
We need a scope to examine a
waveform that we want to
apply to a pair of
electro-chemical cells wired
in series. Currently we
power the cells with 1.0
VDC, and they normally they
draw between 3 and 5 A. It
is thought that cell
performance would improve if
we can cause the chemicals
in the cells to resonate,
hence the desire to
superimpose an AC signal on
top of the DC. We have been
able to explore frequencies
up to 100 kHz for square
waves and pulses and 300 kHz
for sine waves, but not
surprisingly those lowish
frequencies did not help.
We now want to explore
frequencies from about 1 MHz
to as much as we can afford
on a shoestring budget, but
no less than 30 MHz for
square waves and pulses and
50 MHz for sine waves. 100
MHz would be nice, but
there's that budget issue.
The waveforms, at least
initially, would be limited
to 1 V maximum, and never
going negative. We are
thinking that the maximum AC
amplitude would be 0.5 V
peak, or 1.0 V peak to peak,
and that would be
superimposed on a 0.5 V DC
bias voltage. A minimum AC
amplitude would be 0.05 V
peak, or 0.10 V peak to
peak, and that would be
superimposed on a 0.95 DC
bias voltage.
We'd also like to monitor
current if we can find a
shunt that does not distort
the waveform.
An issue is that I can't
guarantee that the final
wiring will give us a common
ground point so we may need
a scope and lead set up
where can can measure two
differential voltages. (Our
Tek 222 with it's isolated
inputs is nice in that
regard, but at 10 MHz
bandwidth won't work for
these higher frequencies.)
So if you guys can point us
in the right direction for
what models of new or used
scopes might work for us. Or
even sell us one of your
surplus working scopes.
Local Craiglist scopes
available that appear to
work from pics and
description: (I know, buyer
beware.)
Tek 2465 (not A or B) $350
firm. (Seems a little high)
Tek 2215A, $100 firm (Not
quite enough bandwidth)
Tek TDS 3052B (No price
given, and I don't know much
about this other than
labeled 500 MHz)
Anritsu MS2711D (I know
nothing about this brand or
model)
We're also going to need an
arbitrary waveform
generator, and the
"superimposed RF on top of
DC" power supply. These
could be the subject of
another posting if there's
any interest, or we could
keep those non scope
subjects off forum.
If it makes any difference,
our 3 person start up is in
Seaford, Delaware.
|
David Hess