Date   
Re: OT: App that keeps track of "Or Best Offer" auctions on eBay to tell you what a seller will accept.

David Berlind
 

Goofbid and other sites/apps that integrate with eBay probably work through eBay's API which has lost functionality (ie: certain fields of data) over the years due to privacy concerns, security issues, GDPR, etc. These changes irreparably break the applications that rely on them in the ways that you are noticing. The same has happened to many other APIs from popular sites.

On May 22, 2019 6:29:04 PM "Tom Gardner" <tggzzz@...> wrote:

Regrettably goofbid appears to return zero results, at the moment.

Maybe ebay have stymied them, maybe they have a simple server problem. I hope it
is the latter.


On 22/05/19 23:12, Dennis Tillman W7PF wrote:
Hi Tom,
While I was searching for the app I tried to describe in my original post I did find WatchCount.com site. I also found the GoofBid site (www.goofbid.com).
MORE IMPORTANTLY I found out where I got the original information from: IT WAS YOU:)

This is the link to the original mail about WatchCount that you sent:
https://groups.io/g/TekScopes/message/148676

I haven't quite figured out what I am doing wrong with GoofBid's eBay Best Offers Tool and eBay Best Offer History Tool or where I first found out about it. It is what I was looking for where you can enter a user's eBay ID into it and it will show you all the times they accepted an offer. At least that is what I think it does. So far I haven't gotten to give me any results at all when I enter a seller name who I know has things they will accept an offer on.

I think they have changed the user interface so I didn't recognize it until just now even though Petru Ulici pointed it out to me yesterday

Dennis Tillman W7PF

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Tom Gardner
Sent: Wednesday, May 22, 2019 1:20 PM
To: TekScopes@groups.io
Subject: Re: [TekScopes] OT: App that keeps track of "Or Best Offer" auctions on eBay to tell you what a seller will accept.

On 22/05/19 19:55, David Berlind wrote:
The results don't just included completed auctions, but also
Buy-It-Now listings that were optionally enabled with the "Make Offer"
button. For those listings, you will never know how much was actually
paid for the item. They only show the Buy-It-Now price. The actual
sale price could have been the Buy-It-Now price, or something less.
Goto watchcount.com and paste the ebay item number into the keywords box.

For example:
https://www.ebay.co.uk/itm/Datron-1061A-multimeter-6-5-digit-DC-volts-AC-volts-Resistance-current-GPIB/113707651429

Therefore item number 113707651429

shows
Seller:
testelectro <http://www.watchcount.com/go/?seller=testelectro&cid=ilu->[efb
<http://www.watchcount.com/go/?cid=ilu-efb-&url=https%3A%2F%2Ffeedback.ebay.co.uk%2Fws%2FeBayISAPI.dll%3FViewFeedback2%26ftab%3DFeedbackAsSeller%26userid%3Dtestelectro>][sld
<http://www.watchcount.com/completed.php?bfw=1&bslr=testelectro#serp>]


View Count:
104
Watch Count:
3 <http://www.watchcount.com/go/?item=113707651429&cid=ilu->
Start Time:
Thursday, 04-Apr-19 08:11:44UTC
End Time:
Friday, 12-Apr-19 13:30:01UTC (40.28 days ago)
Current Bid/Price (GBP):
£ 295.00
Best Offer Enabled
Sold For (GBP):
£ 270.00(check price here? –>) [History
<http://www.watchcount.com/go/?cid=ilu-ihist-113707651429-&url=https%3A%2F%2Foffer.ebay.co.uk%2Fws%2FeBayISAPI.dll%3FViewBidsLogin%26item%3D113707651429>]




Procedure to measure rf watts

Randy.AB9GO
 

Hello everyone,

I have a need to check the calibration on some low power watt meters (10 watts or less, 21 megahertz or less) and was wondering if anybody had a favorite procedure using their scope to measure peak-to-peak rf voltage without letting out the magic smoke. My thought is to use a t connector, hook one side to the transmitter, one side to a dummy load and then the center connector straight to the 10X oscilloscope probe. Any other precautions I should take?

Thank you,
Randy.

Re: Photo Storage Space Solution, was IMPORTANT: Photos are eating up our storage

nonIonizing EMF
 

I was wondering if moving the images and details related like including the link to the groups.io or other post to Tekwiki might be a solution. I'm not sure about the server limitations and expense there however.

Re: 7904 excessive shadow/flare

radioconnection@...
 

Looks like an out of phase ghost image? Signal reflection due to SWR on the probe cable?

Try another signal source and different cable.

Pete

Re: Photo Storage Space Solution, was IMPORTANT: Photos are eating up our storage

Harvey White
 

Didn't tekscopes have some other groups that were created solely for image storage back on Yahoo?

Harvey

On 5/22/2019 7:02 PM, nonIonizing EMF wrote:
I was wondering if moving the images and details related like including the link to the groups.io or other post to Tekwiki might be a solution. I'm not sure about the server limitations and expense there however.




Re: 7904 excessive shadow/flare

unclebanjoman
 

No, the artifact is visible with any type of signal.
It also appears using the signal standardizer. I used the latter today to perform some calibrations on my 7904 and I was very irritated by this halo / flare effect.
With sweep rates of 0.1-0.5 sec and no signal applied is clearly visible the usual "globus" leading/lagging the spot.
Already with moderate brightness the artifact is visible.

Max

Re: Old Tektronix Books

Dave Wise
 

Guilty. Oops. I guess I skipped words and saw what I wished were true.

I know I've read Typical Oscilloscope Circuitry. The physical book, in my hands. But I'm pretty sure I don't own a copy. It's a mystery.
Worldcat.org indicates several libraries with copies, including, for you in northwest Oregon, Pacific University in Forest Grove. You can probably get it via inter-library loan.

Dave Wise

PS: My rotten memory believes that the schematics were 535 and 545.
________________________________________
From: TekScopes@groups.io <TekScopes@groups.io> on behalf of ROLYNN PRECHTL K7DFW <k7dfw@...>
Sent: Wednesday, May 22, 2019 11:10 AM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Old Tektronix Books

The "Typical Oscilloscope Circuitry" book. Rolynn said it was at w140 ("TekWiki"), but I couldn't find it so I asked him where it was in the w140 site.

===========================================================================================

Not even close.

Rolynn said that the:

1961 publication eliminates some.
(1961 publication date eliminates some of the scopes from where the schematics came from)

The power supply might be a 531/535/541 but I'm not going to spend any time with this since the manuals are on TekWiki.

(the manuals for the potential scope candidates are on TekWiki and to do your own detective work to find out which instrument schematics are in the book)

Clear as a bell - to me.

Rolynn

Re: Procedure to measure rf watts

Bob Albert
 

I use my venerable HP410B.  The ac probe has wide bandwidth and the most sensitive range of 1 V should suffice for all but the weakest power from a transmitter.  Full scale corresponds to 20 mW.  Half scale, or 0.5 Volt, 5 mW.
Sure you can use an oscilloscope.  You will have some calculation to do.  Further, you would be able to ascertain whether you are working with something close to a sine wave.
Ideally, use both instruments, one for checking waveform and the other for a quantitative reading.  The load, of course, needs to be purely resistive.  If not, your 'power' reading will be wrong.
In any case, an oscilloscope isn't the best tool for precise measurements.  The trace width and screen nonlinearities need to be considered.  A spectrum analyzer might be a good idea, since it would show each frequency component and allow one to decide if any are large enough to influence the result.  Most spectrum analyzers have 50 or 75 Ohm input already in place; the pitfall there is to make sure you don't burn out the termination.  Ten Watts is too much, and most aren't safe above 1 Watt or less.  A dummy load and attenuator might be a good idea.
When I measure the power out of my ham transmitter I can get an accurate reading with the HP voltmeter.  I use either a dummy load or an antenna with close to 1:1 SWR.  Without the linear amplifier I get around 65-70 V reading (100 W or so) and with the amplifier about 220-250 Volts (over 1 kW), depending on tuning and load quality.  The HP pointer movement is so well damped that I can get peak readings when operating pulsed, such as a series of CW dots.
I also have an oscilloscope to see the wave; I couple it to the system with a loop pickup.  I connect a coaxial cable to the 'scope and short the other end around one of my voltmeter leads.  Thus, inductive pickup.
When I use audio modulation I can measure peak envelope power on the voltmeter.  The 'scope will enable me to adjust the modulation such that I don't get clipping.  I can also verify the performance of the speech processor.
Bob

On Wednesday, May 22, 2019, 4:01:03 PM PDT, Randy.AB9GO <@AB9GO> wrote:

Hello everyone,

I have a need to check the calibration on some low power watt meters (10 watts or less, 21 megahertz or less) and was wondering if anybody had a favorite procedure using their scope to measure peak-to-peak rf voltage without letting out the magic smoke.  My thought is to use a t connector, hook one side to the transmitter, one side to a dummy load and then the center connector straight to the 10X oscilloscope probe. Any other precautions I should take?

Thank you,
Randy.

Re: Procedure to measure rf watts

@0culus
 

On Wed, May 22, 2019 at 04:00 PM, Randy.AB9GO wrote:


Hello everyone,

I have a need to check the calibration on some low power watt meters (10 watts
or less, 21 megahertz or less) and was wondering if anybody had a favorite
procedure using their scope to measure peak-to-peak rf voltage without letting
out the magic smoke. My thought is to use a t connector, hook one side to the
transmitter, one side to a dummy load and then the center connector straight
to the 10X oscilloscope probe. Any other precautions I should take?

Thank you,
Randy.
I will say above anything else, 10W is way too much power to be putting into most test equipment, especially spectrum analyzers. You *will* burn up something in the frontend and then you'll be sad. You want something like an RF sampling tee that will couple a much smaller version of your TX signal into your instrument.

Sean

Re: Procedure to measure rf watts

Richard Knoppow
 

At communication frequencies I use a General Radio 1800A mainly because I have the proper adapter for the probe. The 410B is fine but its adapters for any of the more common coaxial connectors are pretty scarce. Otherwise its fine. The 1800A takes a shell for a GR 874 connector which screws into the end of the probe, the banana plug acting as the center conductor. I then use an N type T with UHF adaptors on two ends and the probe in the center. I have a couple of dummy loads which have been measured on a GR RF bridge so I know their actual impedance at the measurement frequency. In general a DC resistance measurement comes close and they are pretty non-reactive. I can then calculate the power with reasonable accuracy.
Both the 1800A and 410B have single diode rectifiers for RF and both have the usual characteristic of being square law at small voltages transitioning to peak reading at high voltages. The scales are calibrated in the RMS value of a sine wave and both have different scales for low and high voltages as required by the characteristic of the diode. I have calibrated my MFJ tuner/SWR meter/power meter using this arrangement. It seems to be reasonably accurate. A scope could be used but as you say requires some calculation because it reads peak-to-peak.
Nothing is as simple as it seems or as you would prefer.
OTOH, a scope can tell you an awful lot about what is going on in the transmitter.

On 5/22/2019 5:39 PM, Bob Albert via Groups.Io wrote:
I use my venerable HP410B.  The ac probe has wide bandwidth and the most sensitive range of 1 V should suffice for all but the weakest power from a transmitter.  Full scale corresponds to 20 mW.  Half scale, or 0.5 Volt, 5 mW.
Sure you can use an oscilloscope.  You will have some calculation to do.  Further, you would be able to ascertain whether you are working with something close to a sine wave.
Ideally, use both instruments, one for checking waveform and the other for a quantitative reading.  The load, of course, needs to be purely resistive.  If not, your 'power' reading will be wrong.
In any case, an oscilloscope isn't the best tool for precise measurements.  The trace width and screen nonlinearities need to be considered.  A spectrum analyzer might be a good idea, since it would show each frequency component and allow one to decide if any are large enough to influence the result.  Most spectrum analyzers have 50 or 75 Ohm input already in place; the pitfall there is to make sure you don't burn out the termination.  Ten Watts is too much, and most aren't safe above 1 Watt or less.  A dummy load and attenuator might be a good idea.
When I measure the power out of my ham transmitter I can get an accurate reading with the HP voltmeter.  I use either a dummy load or an antenna with close to 1:1 SWR.  Without the linear amplifier I get around 65-70 V reading (100 W or so) and with the amplifier about 220-250 Volts (over 1 kW), depending on tuning and load quality.  The HP pointer movement is so well damped that I can get peak readings when operating pulsed, such as a series of CW dots.
I also have an oscilloscope to see the wave; I couple it to the system with a loop pickup.  I connect a coaxial cable to the 'scope and short the other end around one of my voltmeter leads.  Thus, inductive pickup.
When I use audio modulation I can measure peak envelope power on the voltmeter.  The 'scope will enable me to adjust the modulation such that I don't get clipping.  I can also verify the performance of the speech processor.
Bob
On Wednesday, May 22, 2019, 4:01:03 PM PDT, Randy.AB9GO <@AB9GO> wrote:
Hello everyone,
I have a need to check the calibration on some low power watt meters (10 watts or less, 21 megahertz or less) and was wondering if anybody had a favorite procedure using their scope to measure peak-to-peak rf voltage without letting out the magic smoke.  My thought is to use a t connector, hook one side to the transmitter, one side to a dummy load and then the center connector straight to the 10X oscilloscope probe. Any other precautions I should take?
Thank you,
Randy.
--
Richard Knoppow
dickburk@...
WB6KBL

Re: Procedure to measure rf watts

Jim Ford
 

Definitely use a directional coupler or an attenuator.I assume that the flow-through wattmeters like those made by Bird have couplers inside those plug-in modules.Jim Ford Sent from my Verizon, Samsung Galaxy smartphone

-------- Original message --------From: sdturne@q.com Date: 5/22/19 6:25 PM (GMT-08:00) To: TekScopes@groups.io Subject: Re: [TekScopes] Procedure to measure rf watts On Wed, May 22, 2019 at 04:00 PM, Randy.AB9GO wrote:>> Hello everyone,> > I have a need to check the calibration on some low power watt meters (10 watts> or less, 21 megahertz or less) and was wondering if anybody had a favorite> procedure using their scope to measure peak-to-peak rf voltage without letting> out the magic smoke. My thought is to use a t connector, hook one side to the> transmitter, one side to a dummy load and then the center connector straight> to the 10X oscilloscope probe. Any other precautions I should take?> > Thank you,> Randy.>I will say above anything else, 10W is way too much power to be putting into most test equipment, especially spectrum analyzers. You *will* burn up something in the frontend and then you'll be sad. You want something like an RF sampling tee that will couple a much smaller version of your TX signal into your instrument.Sean

Re: Latest firmware for TDS210 and TDS2CM?

Jared Cabot
 

I might actually have the newer version of the hardware.

My scope firmware is v2.03 and my module (It's actually a TDS2MM, not TDS2CM as I previously wrote) is v1.04
Are there any later versions than these? And is there any info on that programming fixture? I assume it would be almost unobtanium....

497p front panel cal failure (CF and Ref Lvl)

radioconnection@...
 

The first test in the manual for the center frequency and reference level self calibration fails. Otherwise, the instrument seems to be working normally. I can't find a detailed trouble shooting chart for that error.

Any suggestions where to start?

Pete

Re: Procedure to measure rf watts

@0culus
 

Another option if you need to do this a lot might be a proper RF communications test set. HP/Agilent made these, and also Marconi that I know of. These instruments combine a lot of different functionality and, from what I've seem, usually have considerably more input power handling capability than spectrum analyzers. IIRC I've seen a Marconi unit that was marked 75 W max, but that could be my memory banks failing too. :o)

Sean

Re: Procedure to measure rf watts

Jim Potter
 

Randy,

The technique is to use calibrated attenuators to bring the power level down to 10 mW or so. 10 mW is 1V peak or 2V Pk-pk. Ideally you should calibrate the scope, but to do that you need a calibrated signal generator and a 50 Ohm load. If you frequency is well within the bandwidth of the scope you can calibrate by other means or accept the scope calibration as is.

If you have 10 W you need about 30 dB of attenuation. Its not critical as long as you get the signal into the amplitude range of the scope. It's best to be at the few volts pk-pk not down in the mV. You also need to use the scope at 50 Ohms input impedance. If it doesn't have a 50 Ohm setting then a Tee and a terminator will do for frequencies below 20 or 30 MHz. Above that you need an accurate 50 Ohm in-line terminator.

You then measure the pk-pk volts on the scope. The power into the scope is Ps =1/4 Vpp^2/R where R is 50 Ohms. The power is P = 1/2 V^2/R where V is the peak voltage and Vpp = 2*V is the pk-pk voltage.

Now you need to correct for the attenuator. The attenuation factor is 10^(A/10) where A is the attenuator attenuation. The power from your amplifier is then Pa = Ps * 10^(A/10).

One thing to be careful of is harmonics. If harmonics are an issue you need an appropriate low pass filter. It needs to be calibrated at your operating frequency and it's attenuation needs to be added to the attenuator attenuation.

If you are not used to working with rf this may be too brief an explanation.

I use a Tek 2467B to measure peak power of rf pulses at 425 MHz all the time. This is outside the scope bandwidth, so I calibrate the scope with a CW signal and an average power meter. The 2467B reads about 0.7 V for a 1 V signal at 425 MHz. This lets me get accurate peak power readings with out buying a peak power meter. Used Gigatronics peak power meters and heads run about $4k total used. The 2467B is under a $1000. (That's a guess. It's been a few years since I've purchased one.)

de K9GXC, Jim

At 07:25 PM 5/22/2019, you wrote:
On Wed, May 22, 2019 at 04:00 PM, Randy.AB9GO wrote:


Hello everyone,

I have a need to check the calibration on some low power watt
meters (10 watts
or less, 21 megahertz or less) and was wondering if anybody had a favorite
procedure using their scope to measure peak-to-peak rf voltage
without letting
out the magic smoke. My thought is to use a t connector, hook one
side to the
transmitter, one side to a dummy load and then the center
connector straight
to the 10X oscilloscope probe. Any other precautions I should take?

Thank you,
Randy.
I will say above anything else, 10W is way too much power to be putting into most test equipment, especially spectrum analyzers. You *will* burn up something in the frontend and then you'll be sad. You want something like an RF sampling tee that will couple a much smaller version of your TX signal into your instrument.

Sean

James M. Potter, PhD, President
JP Accelerator Works, Inc.
2245 47th Street
Los Alamos, NM 87544

TEL: 505-690-8701

Re: Procedure to measure rf watts

Jim Potter
 

If you use a directional coupler you need to be sure that it is calibrated properly. Unless you have a fully calibrated 50 Ohm system your measurement is nothing more than a WAG (Wild A$$ Guess). The higher the frequency the more complicated it is to get accurate measurements.


At 07:54 PM 5/22/2019, Jim Ford wrote:
Definitely use a directional coupler or an attenuator.I assume that the flow-through wattmeters like those made by Bird have couplers inside those plug-in modules.Jim Ford Sent from my Verizon, Samsung Galaxy smartphone --------
Original message --------From: sdturne@q.com Date: 5/22/19 6:25 PM (GMT-08:00) To: TekScopes@groups.io Subject: Re: [TekScopes] Procedure to measure rf watts On Wed, May 22, 2019 at 04:00 PM, Randy.AB9GO wrote:>> Hello everyone,> > I have a need to check the calibration on some low power watt meters (10 watts> or less, 21 megahertz or less) and was wondering if anybody had a favorite> procedure using their scope to measure peak-to-peak rf voltage without letting> out the magic smoke. My thought is to use a t connector, hook one side to the> transmitter, one side to a dummy load and then the center connector straight> to the 10X oscilloscope probe. Any other precautions I should take?> > Thank you,> Randy.>I will say above anything else, 10W is way too much power to be putting into most test equipment, especially spectrum analyzers. You *will* burn up something in the frontend and then you'll be sad. You want something like an RF sampling tee that will couple a much smaller version of your TX signal into your instrument.Sean
James M. Potter, PhD, President
JP Accelerator Works, Inc.
2245 47th Street
Los Alamos, NM 87544

TEL: 505-690-8701

Re: 7904 excessive shadow/flare

Chuck Harris
 

The 7904, because of its very high anode voltage, and its
mesh lens is one of the worst scopes in existence for reflections
and flare inside of the CRT. But I like it anyway.

-Chuck Harris

unclebanjoman wrote:

No, the artifact is visible with any type of signal.
It also appears using the signal standardizer. I used the latter today to perform some calibrations on my 7904 and I was very irritated by this halo / flare effect.
With sweep rates of 0.1-0.5 sec and no signal applied is clearly visible the usual "globus" leading/lagging the spot.
Already with moderate brightness the artifact is visible.

Max



Re: Procedure to measure rf watts

Bob Albert
 

Richard I pretty much agree with your comments.  But I'd like to add that, at HF, precision connectors and fancy adapters are overkill.  I have a T connector, UHF type, in the line from the rig.  I plug into that an adapter from UHF to BNC and another adapter from there to binding posts.  I connect the HP 410B to the binding posts.
Now of course I am aware that this is not good practice.  But I suggest that, for frequecies below 30 MHz, it's close enough.  There are no discontinuities more than an inch or so, much less than what rule of thumb (one tenth wavelength) says.  My readings are close to what I expect.  And if there is an error, well it can't be great and I don't think FCC will be breathing down my neck for running too much power.
Should I desire to work at 2 meters, then I might be more rigorous.  (I am reminded of an old exam question for ham license that suggested using an HF SWR meter at 2 meters if that's all you have, and it's close enough.)
Bob K6DDX

On Wednesday, May 22, 2019, 6:46:39 PM PDT, Richard Knoppow <dickburk@...> wrote:

    At communication frequencies I use a General Radio 1800A
mainly because I have the proper adapter for the probe. The 410B
is fine but its adapters for any of the more common coaxial
connectors are pretty scarce. Otherwise its fine. The 1800A takes
a  shell for a GR 874 connector which screws into the end of the
probe, the banana plug acting as the center conductor. I then use
an N type T with UHF adaptors on two ends and the probe in the
center. I have a couple of dummy loads which have been measured
on a GR RF bridge so I know their actual impedance at the
measurement frequency. In general a DC resistance measurement
comes close and they are pretty non-reactive. I can then
calculate the power with reasonable accuracy.
    Both the 1800A and  410B have single diode rectifiers for RF
and both have the usual characteristic of being square law at
small voltages transitioning to peak reading at high voltages.
The scales are calibrated in the RMS value of a sine wave and
both have different scales for low and high voltages as required
by the characteristic of the diode.  I have calibrated my MFJ
tuner/SWR meter/power meter using this arrangement. It seems to
be reasonably accurate. A scope could be used but as you say
requires some calculation because it reads peak-to-peak.
    Nothing is as simple as it seems or as you would prefer.
    OTOH, a scope can tell you an awful lot about what is going
on in the transmitter.

On 5/22/2019 5:39 PM, Bob Albert via Groups.Io wrote:
  I use my venerable HP410B.  The ac probe has wide bandwidth and the most sensitive range of 1 V should suffice for all but the weakest power from a transmitter.  Full scale corresponds to 20 mW.  Half scale, or 0.5 Volt, 5 mW.
Sure you can use an oscilloscope.  You will have some calculation to do.  Further, you would be able to ascertain whether you are working with something close to a sine wave.
Ideally, use both instruments, one for checking waveform and the other for a quantitative reading.  The load, of course, needs to be purely resistive.  If not, your 'power' reading will be wrong.
In any case, an oscilloscope isn't the best tool for precise measurements.  The trace width and screen nonlinearities need to be considered.  A spectrum analyzer might be a good idea, since it would show each frequency component and allow one to decide if any are large enough to influence the result.  Most spectrum analyzers have 50 or 75 Ohm input already in place; the pitfall there is to make sure you don't burn out the termination.  Ten Watts is too much, and most aren't safe above 1 Watt or less.  A dummy load and attenuator might be a good idea.
When I measure the power out of my ham transmitter I can get an accurate reading with the HP voltmeter.  I use either a dummy load or an antenna with close to 1:1 SWR.  Without the linear amplifier I get around 65-70 V reading (100 W or so) and with the amplifier about 220-250 Volts (over 1 kW), depending on tuning and load quality.  The HP pointer movement is so well damped that I can get peak readings when operating pulsed, such as a series of CW dots.
I also have an oscilloscope to see the wave; I couple it to the system with a loop pickup.  I connect a coaxial cable to the 'scope and short the other end around one of my voltmeter leads.  Thus, inductive pickup.
When I use audio modulation I can measure peak envelope power on the voltmeter.  The 'scope will enable me to adjust the modulation such that I don't get clipping.  I can also verify the performance of the speech processor.
Bob
      On Wednesday, May 22, 2019, 4:01:03 PM PDT, Randy.AB9GO <@AB9GO> wrote:
 
  Hello everyone,

I have a need to check the calibration on some low power watt meters (10 watts or less, 21 megahertz or less) and was wondering if anybody had a favorite procedure using their scope to measure peak-to-peak rf voltage without letting out the magic smoke.  My thought is to use a t connector, hook one side to the transmitter, one side to a dummy load and then the center connector straight to the 10X oscilloscope probe. Any other precautions I should take?

Thank you,
Randy.

--
Richard Knoppow
dickburk@...
WB6KBL

Re: Photo Storage Space Solution, was IMPORTANT: Photos are eating up our storage

 

Hi Harvey,
Not that I know of. You may be thinking of TekScopes2 and there was another one devoted to Tek Archives but the name escapes me. It may have been TekScopesArc or something like that.
Dennis Tillman W7PF

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Harvey White
Sent: Wednesday, May 22, 2019 4:24 PM
Subject: Re: [TekScopes] Photo Storage Space Solution, was IMPORTANT: Photos are eating up our storage

Didn't tekscopes have some other groups that were created solely for image storage back on Yahoo?
Harvey


On 5/22/2019 7:02 PM, nonIonizing EMF wrote:
I was wondering if moving the images and details related like including the link to the groups.io or other post to Tekwiki might be a solution. I'm not sure about the server limitations and expense there however.



--
Dennis Tillman W7PF
TekScopes Moderator

Re: 7904 excessive shadow/flare

Roger Evans
 

To my eye each of the shadow peaks and troughs of the sine wave lies on a straight line joining the real peak/trough to the CRT centre, but farther out. This should be very obvious at say 100msec/div. I would guess the probable cause is the CRT cathode voltage dropping out of regulation due to a HV capacitor failure. If you don't have a HV probe you should be able to see the ripple on the feedback to the regulator.

Regards,

Roger