Re: Mosley traps measurements question
Thanks for the info.
Luckily I figured out the capicator value and was able to derive the frequencies of the trap. Also the Nano VNA in Smith format will work. I probably will post Mosley info on the trap group. It applies to many multi band antennas.
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I should have added that a dead or alive function using the vna as a troubleshooting aid is a reasonable application.
Assume the probe is essentially ideal as far as the circuit under test is concerned. That is to say, zero loading. An
active stage input,output could be monitored as a s21 measure. Hence a signal trace analyzer. That does have utility.
Alan
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Re: SMA connector pulled off of cable.
Short link to that Amazon cable assembly would be the URL to get to Amazon then add /dp/B07YH9NNDQ
I always use the smile.amazon since I donate to a good cause.
--
73 de Phil KE3FL
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Thinking out loud, it's a unidirectional device, which maybe useful on port 2 in some way, but not useful on port 1 in any way that I can think of. Seems more appropriate for a scope, SA, or RF voltmeter.
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I build one of my own a few years back for trouble shooting.
You hold it near the oscillator, you hold it near the amp, you hold it near thedriver, you hold it near the final amp.? In a few seconds you know what area ofa transmitter is not doing it's job.? ? Like Cliff said, great for trouble shooting, butnot precision measurements.? ? Tiny SA recommended for that job vs the NanoVNA.Kent 2E0VAA/W5
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On Wednesday, August 18, 2021, 06:17:50 AM CDT, davebb123456 <davidbrowne76@...> wrote: Hi Clif Please let me know how you get on with it Maybe I can use it with my TS2000 ?thanks Dave 2E0DMB On Wed, 18 Aug 2021, 10:30 avvidclif, <clif@...> wrote: Nobody said anything about calibrating it. It's a probe looking for
signals with some measure of safety. Once found, then if needed,
calibration could be done. This a troubleshooting tool not a lab
measurement/design.
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This probe is just a capacitor input coupled FET source follower with a voltage regulator to run the FET. Input capacitance loading in in 10-15 pF range.
Over a limited freq range it provides a high impedance input.
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Hi Clif
Please let me know how you get on with it
Maybe I can use it with my TS2000 ?thanks Dave
2E0DMB
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On Wed, 18 Aug 2021, 10:30 avvidclif, <clif@...> wrote: Nobody said anything about calibrating it. It's a probe looking for
signals with some measure of safety. Once found, then if needed,
calibration could be done. This a troubleshooting tool not a lab
measurement/design.
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Nobody said anything about calibrating it. It's a probe looking for signals with some measure of safety. Once found, then if needed, calibration could be done. This a troubleshooting tool not a lab measurement/design.
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On 18/8/21 11:15 am, Ray Anderson wrote: That probe might be useful for use with the spectrum analyzer to provide a means to probe some high-z circuits without loading them down with the 50 ohms presented by the SA input, but I think it would be fairly useless with the VNA. I'm not sure that I agree with this. For typical simple use of a VNA with the ports of a 2-port DUT, sure, but if you're wanting for example to examine standing waves in a multi-pole filter or a DUT with more than 2 ports, RF switches and active probes are very useful tools to have. - Roland 9V1RT (whose fingers are still sensitive after hundreds of N-connector disconnect-connect cycles on the weekend while tuning a duplexer without the aid of RF switches or an active probe)
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Active RF probing with the VNA is useful.
However, you would have to figure out how to apply this probe to a cal and measurement routine
that would provide useful results. For example, an in-circuit S21 response as outlined in the note above.
Alan
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That probe might be useful for use with the spectrum analyzer to provide a means to probe some high-z circuits without loading them down with the 50 ohms presented by the SA input, but I think it would be fairly useless with the VNA.
Ray WB6TPU
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On Aug 17, 2021, at 7:58 PM, avvidclif <clif@...> wrote:
?For those looking for a probe for the NanoVNA or Tiny SA you might check out the following. It has a dc block and should work fine. I bought but haven't tried them yet. It's cheap enough it won't hurt if it doesn't work.
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For those looking for a probe for the NanoVNA or Tiny SA you might check out the following. It has a dc block and should work fine. I bought but haven't tried them yet. It's cheap enough it won't hurt if it doesn't work.
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Re: SMA connector pulled off of cable.
Those are unobtanium around these parts so I have to
get what's available at Ali, Ebay etc.
Anyway I prefer PTFE coax and soldered connectors.
RG316DS would be best (for me) but can't find non fake ones ...
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On Wed, 18 Aug 2021 at 04:02, Clyde Spencer <cftr01b@...> wrote: OK lets run this off the cliff. If you have a propensity to build your own
cables I would suggest LMR195 ultraflex cable. This is the same size and
very similar characteristics as RG142but is much more flexible. LMR-195
ultraflex is a 100% shielded cable.There are a variety of crimp connectors
for LMR195 ultraflex and somewhat reasonable prices. Using cables from this
LMR195 ultraflex are more robust than those made with the RG316 cable and
provide less loss perfoot.
*Clyde K. Spencer*
On Tue, Aug 17, 2021 at 9:54 PM Dragan Milivojevic <
d.milivojevic@...>
wrote:
Get some semi rigid cables, the shield is soldered to the connector
shell so it won't come off any time soon. RG402 is the thicker and stiffer
variant, RG405 is the thinner, more flexible one.
I got these (and some other M-M, M-F variants):
Avoid RG316, I bought a number of those on AliExpress and all were fake
(non PTFE insulator).
They can't use regular plastic as dielectric on semi rigid ones, since the
shield
has to be dipped in solder, so all semi rigid cables use real PTFE.
The linked store also has real RG142, but those are quite springy so not as
convenient to use.
On Wed, 18 Aug 2021 at 02:52, Bill Klymus W5PB <bktx75@...> wrote:
This past weekend, I accidentally pulled the SMA connector off one of the
thin coaxial cables. The outer threaded portion came off, but the
center
pinwas still attached. The cable checks out, or at least seems to. Should I
be wary of it's reliability? And if so, what is a good replacement source.
I worry about these cables, being slightly stiff, that they can only
take
so much bending before they will fail, anyway.
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Re: SMA connector pulled off of cable.
OK lets run this off the cliff. If you have a propensity to build your own cables I would suggest LMR195 ultraflex cable. This is the same size and very similar characteristics as RG142but is much more flexible. LMR-195 ultraflex is a 100% shielded cable.There are a variety of crimp connectors for LMR195 ultraflex and somewhat reasonable prices. Using cables from this LMR195 ultraflex are more robust than those made with the RG316 cable and provide less loss perfoot. *Clyde K. Spencer* On Tue, Aug 17, 2021 at 9:54 PM Dragan Milivojevic <d.milivojevic@...> wrote: Get some semi rigid cables, the shield is soldered to the connector
shell so it won't come off any time soon. RG402 is the thicker and stiffer
variant, RG405 is the thinner, more flexible one.
I got these (and some other M-M, M-F variants):
Avoid RG316, I bought a number of those on AliExpress and all were fake
(non PTFE insulator).
They can't use regular plastic as dielectric on semi rigid ones, since the
shield
has to be dipped in solder, so all semi rigid cables use real PTFE.
The linked store also has real RG142, but those are quite springy so not as
convenient to use.
On Wed, 18 Aug 2021 at 02:52, Bill Klymus W5PB <bktx75@...> wrote:
This past weekend, I accidentally pulled the SMA connector off one of the
thin coaxial cables. The outer threaded portion came off, but the center
pinwas still attached. The cable checks out, or at least seems to. Should I
be wary of it's reliability? And if so, what is a good replacement source.
I worry about these cables, being slightly stiff, that they can only take
so much bending before they will fail, anyway.
|
Re: SMA connector pulled off of cable.
Get some semi rigid cables, the shield is soldered to the connector
shell so it won't come off any time soon. RG402 is the thicker and stiffer
variant, RG405 is the thinner, more flexible one.
I got these (and some other M-M, M-F variants):
Avoid RG316, I bought a number of those on AliExpress and all were fake
(non PTFE insulator).
They can't use regular plastic as dielectric on semi rigid ones, since the
shield
has to be dipped in solder, so all semi rigid cables use real PTFE.
The linked store also has real RG142, but those are quite springy so not as
convenient to use.
toggle quoted message
Show quoted text
On Wed, 18 Aug 2021 at 02:52, Bill Klymus W5PB <bktx75@...> wrote: This past weekend, I accidentally pulled the SMA connector off one of the
thin coaxial cables. The outer threaded portion came off, but the center
pinwas still attached. The cable checks out, or at least seems to. Should I
be wary of it's reliability? And if so, what is a good replacement source.
I worry about these cables, being slightly stiff, that they can only take
so much bending before they will fail, anyway.
|
Re: SMA connector pulled off of cable.
VNA cables need to be considered as consumables, they will eventually break or the connectors become worn. There are many sources of flexible cables online, Amazon and EBay have many. There is nothing magic about the ones that come with the nanoVNA, they are just run of the mill stuff. I always mark mine so that I can return them to the orientation and port they were on when I did a calibration.
73, Don N2VGU
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Re: SMA connector pulled off of cable.
Save the broken cable. Maybe you can use it when building a test fixture or similar. *Clyde K. Spencer* On Tue, Aug 17, 2021 at 9:16 PM Clyde Spencer via groups.io <cftr01b= [email protected]> wrote: I would no longer trust that cable. You can get a pair of these cables from
Amazon.com or other sources. The screen shot below is from Amazon.com
[image: image.png]
*Clyde K. Spencer*
On Tue, Aug 17, 2021 at 8:52 PM Bill Klymus W5PB <bktx75@...> wrote:
This past weekend, I accidentally pulled the SMA connector off one of the
thin coaxial cables. The outer threaded portion came off, but the center
pinwas still attached. The cable checks out, or at least seems to. Should I
be wary of it's reliability? And if so, what is a good replacement source.
I worry about these cables, being slightly stiff, that they can only take
so much bending before they will fail, anyway.
|
Re: SMA connector pulled off of cable.
I would no longer trust that cable. You can get a pair of these cables from
Amazon.com or other sources. The screen shot below is from Amazon.com
[image: image.png]
*Clyde K. Spencer*
toggle quoted message
Show quoted text
On Tue, Aug 17, 2021 at 8:52 PM Bill Klymus W5PB <bktx75@...> wrote: This past weekend, I accidentally pulled the SMA connector off one of the
thin coaxial cables. The outer threaded portion came off, but the center
pinwas still attached. The cable checks out, or at least seems to. Should I
be wary of it's reliability? And if so, what is a good replacement source.
I worry about these cables, being slightly stiff, that they can only take
so much bending before they will fail, anyway.
|
SMA connector pulled off of cable.
This past weekend, I accidentally pulled the SMA connector off one of the thin coaxial cables. The outer threaded portion came off, but the center pinwas still attached. The cable checks out, or at least seems to. Should I be wary of it's reliability? And if so, what is a good replacement source. I worry about these cables, being slightly stiff, that they can only take so much bending before they will fail, anyway.
|
Re: danger measuring antenna
Yes, it was also something for the final DC block from the 6146 plate voltage to work against. Dave - W?LEV On Tue, Aug 17, 2021 at 11:40 PM Brian D < g3vgz-groups.io@...> wrote: "David Eckhardt" <davearea51a@...> wrote:
I
remember my Novice transmitter, the Heathkit DX-40. It had a large-valued
RF choke from the back of the PL-259 to chassis. The sole purpose of that
RF choke was to keep voltages from building up on the feedline - same as
the resistor in question. Manly to prevent dangerous voltages on the feedline due to breakdown in the
plate capacitor leaking HT onto the feedline, essential on high power valve
PAs.
--
Brian D
G3VGZ G8AOE G3T
IO94im
-- *Dave - W?LEV* *Just Let Darwin Work*
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Lou W7HV
Donald S Brant Jr
