Products > Test Equipment

Test Equipment Anonymous (TEA) group therapy thread

<< < (2053/27435) > >>

tggzzz:

--- Quote from: bd139 on May 03, 2018, 09:01:26 pm ---Quick test run of the Leader 17A on the scope.

6.5MHz. Nice clean sines!

--- End quote ---

You need a spectrum analyser to determine that! Scopes are not known for their input linearity, and gross crap looks OK in the time domain.

Specmaster:

--- Quote from: tautech on May 03, 2018, 11:11:03 pm ---
--- Quote from: Specmaster on May 03, 2018, 11:02:21 pm ---
--- Quote from: bd139 on May 03, 2018, 10:36:58 pm ---I’d stuff a 75 ohm BNC on the generator straight up and build the pad inside a Pomona box you plug into it. Then when you get something else 75 ohm it’ll be useable as well.

I’d ony do this to the RF out.

--- End quote ---
Still a little puzzled about this seeing as the only 50 ohm inputs I have are the TF930 and the HP1740A which is switchable between 50ohm and 1M, all the other scopes tend to be 1M and also of course the TF930 can also be switched between 1M and 50ohm. If IIRC the only time the 50ohm input on the 1740A gets mentioned really is on some specific calibration tests?

Also of course when using the signal generator for setting up radios, whats the impedance there when the terminations are more likely going via small crock clips?

--- End quote ---
There are probes that specify they must be terminated into 50 \$\Omega\$.
Without an internal 50  \$\Omega\$ input you then need used a feed through.

--- End quote ---
I'm only really looking at frequencies used in normal domestic broadcast radios, from 100KHz to 108MHz is this strictly necessary? It is only for aligning the IF's and the oscillator tuning to correct align stations on the dial?                                                                                                       

Specmaster:

--- Quote from: tggzzz on May 03, 2018, 11:40:07 pm ---
--- Quote from: Specmaster on May 03, 2018, 11:02:21 pm ---Still a little puzzled about this seeing as the only 50 ohm inputs I have are the TF930 and the HP1740A which is switchable between 50ohm and 1M, all the other scopes tend to be 1M and also of course the TF930 can also be switched between 1M and 50ohm. If IIRC the only time the 50ohm input on the 1740A gets mentioned really is on some specific calibration tests?

--- End quote ---

The excellent "low" impedance Z0 "resistive divider" probes have to be terminated in 50ohms, as do other classes of probes.

Those are actually a higher input impedance than so-called "high" impedance *10 probes (when input capacitance is included), and have a much higher bandwidth. Examples: 1.5GHz HP10020A or 6GHz HP54006A.

--- End quote ---
Why would I be attaching probes to a signal generator? I'm more likely am I not (unless I'm missing something) be using a a lead terminating in a BNC at one end and a pair croc clips at the other. The highest bandwidth scope I'll be using is 100MHz. I'm only using the signal generator for normal domestic radio broadcast radios between 100 KHz and 108MHz?

BravoV:

--- Quote from: Ero-Shan on May 03, 2018, 08:00:24 pm ---
--- Quote from: BravoV on May 03, 2018, 01:50:44 pm ---Not test equipment though  :P, but in this case these are categorized as Test Component as these will be used for the GPSDO board. A Huber+Suhner outdoor GPS antenna and Rosenberger N type male connectors.

--- End quote ---
As I have ordered my TruePosition GPSDO this very day, I'm now in need of an antenna, too. All I can find are terribly cheap antennas for cars and a few for boats. I have no real idea, though, whether they work with this board. :(
--- End quote ---

Well, at the Trueposition GPDSO big thread here, there are success using small patch antenna.

I'm a noob too, lets alone RF things, from what I read at the datasheet, the Furuno GPS receiver can drive a 50 Ohm LNA/active antenna at 5V 20ma, as this is typical for GPS.

Some can get good signal using small antenna at window sill like bd139 does, while here, I don't that kind of luxury as at window even I protruded the antenna head out, its still blocked by the longer protruding roof and also lots of trees with dense leafs, and the best only at 2 or 3 satellites and unstable. :-[

Keep me updated too as I want to learn from your experience.

bd139:

--- Quote from: tggzzz on May 03, 2018, 11:43:07 pm ---
--- Quote from: bd139 on May 03, 2018, 09:01:26 pm ---Quick test run of the Leader 17A on the scope.

6.5MHz. Nice clean sines!

--- End quote ---

You need a spectrum analyser to determine that! Scopes are not known for their input linearity, and gross crap looks OK in the time domain.

--- End quote ---

Of course, which is why I need one, but you can usually see anything more than about 30dBc if you’re running 10-20% of the scope’s bandwidth however as they look pretty nasty.  Enough to do a “more LPF needed” tests on a TX for example. Also if you have a receiver you can use it and the S meter as a crude SA and tune the harmonics.

Navigation

[0] Message Index

[#] Next page

[*] Previous page

There was an error while thanking
Thanking...
Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod