Re: Protecting (tr)uSDX against high SWR
I have a ZM-2 that I built. If anyone wants to borrow it to try it out with your (tr)uSDX or other let me know.
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The best way to protect? (tr)uSDX against high SWR is to use a proper antenna tuner like ZM-2 ATU that will protect the finals during the antenna tuning.<image.png>
73 Ned AC6YY
Connie,
I agree completely. What is the effect on the spectrum, particularly on SSB, which may easily be distorted due to the diode. I think that the failure mode is due to the high voltage as the 3 FETs can dissipate the couple of watts of reflected power.
It could also be neat fix if the diode is more or less transparent under normal operating conditions. It might be interesting to run an experiment with the diode biased with the peak operating voltage on the FETs using a VNA to see what its RF characteristics are in the HF bands. I have never seen an RF amp. that uses this kind of protection.
Dave W6VYC
On Friday, June 14, 2024 at 12:39:57 PM PDT, Connie W6EFI via <stillinger= [email protected]> wrote:
Is there a side-by-side test documented anywhere???? Ie, showing that the radio is destroyed without the zener diode under the same conditions otherwise??? I couldn't find one.?? They're cheap -- you'd think someone would love to blow one up for the views.
I've done a little searching and all I can find as the origin for this recommendation is just one guy with a self-assembled kit who blew his radio up in an unknown way with unknown power even though he had a tuner inline and was presumably tuned up, and he doesn't know what the root cause was, and then said he'd install the zener just in case.
As for WB2CBA (Barb), he just shows that his radio still works.? He didn't do a side-by-side test.??? And it's not a TruSDX.?? Maybe he could have painted it blue or stuck a bandaid to the back of the radio instead and shown that the radio still worked after a high-swr test.?? Look!?? Painting it blue works!
DL2MAN recommends against adding the zener.?? (His recommendation is boring, just use low power for tuning.? Personally I tune by ear before any kind of tx'ing.?? Works great if you have the ear and the tuner.) ?? Also I had a friend (sadly SK now) who gave his TruSDX a hard workout for a good while and told me that it was pretty robust against mismatch.
I don't think "voltage reflected back into the radio" is exactly the problem with mismatched impedances anyway so maybe the zener works, but maybe not for its breakdown threshold; maybe it just changes the tuning.?? Or maybe it works as well as a bandaid.??? Gotta show me some measurements or a side-by-side test before I'm convinced.??
For all of these reasons, and the fact that it's a cheap radio, and any mod activity introduces unknown risk (which is why regression testing exists), I think I'll save myself the trouble for now. ? I am still open to to the idea and interested to see if any more evidence comes in, in which case it's easy enough to add the zener.???? Or if I blow up this radio in which case you can give me a good Nelson "haha!"?? (Simpsons reference)
73,
Connie? W6EFI
Connie Stillinger
650-380-2018
On Friday, June 14th, 2024 at 10:37 AM, Doug Hendricks < ki6ds1@...> wrote:
Thank you Hiroki for your validation.? ?I heartedly encourage everyone who has usdx radios,? including the one from Ed Fong to do this simple mod.
-- Connie KN2EFI
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Re: Protecting (tr)uSDX against high SWR
The best way to protect? (tr)uSDX against high SWR is to use a proper antenna tuner like ZM-2 ATU that will protect the finals during the antenna tuning.73 Ned AC6YY
Connie,
I agree completely. What is the effect on the spectrum, particularly on SSB, which may easily be distorted due to the diode. I think that the failure mode is due to the high voltage as the 3 FETs can dissipate the couple of watts of reflected power.
It could also be neat fix if the diode is more or less transparent under normal operating conditions. It might be interesting to run an experiment with the diode biased with the peak operating voltage on the FETs using a VNA to see what its RF characteristics are in the HF bands. I have never seen an RF amp. that uses this kind of protection.
Dave W6VYC
On Friday, June 14, 2024 at 12:39:57 PM PDT, Connie W6EFI via <stillinger= [email protected]> wrote:
Is there a side-by-side test documented anywhere???? Ie, showing that the radio is destroyed without the zener diode under the same conditions otherwise??? I couldn't find one.?? They're cheap -- you'd think someone would love to blow one up for the views.
I've done a little searching and all I can find as the origin for this recommendation is just one guy with a self-assembled kit who blew his radio up in an unknown way with unknown power even though he had a tuner inline and was presumably tuned up, and he doesn't know what the root cause was, and then said he'd install the zener just in case.
As for WB2CBA (Barb), he just shows that his radio still works.? He didn't do a side-by-side test.??? And it's not a TruSDX.?? Maybe he could have painted it blue or stuck a bandaid to the back of the radio instead and shown that the radio still worked after a high-swr test.?? Look!?? Painting it blue works!
DL2MAN recommends against adding the zener.?? (His recommendation is boring, just use low power for tuning.? Personally I tune by ear before any kind of tx'ing.?? Works great if you have the ear and the tuner.) ?? Also I had a friend (sadly SK now) who gave his TruSDX a hard workout for a good while and told me that it was pretty robust against mismatch.
I don't think "voltage reflected back into the radio" is exactly the problem with mismatched impedances anyway so maybe the zener works, but maybe not for its breakdown threshold; maybe it just changes the tuning.?? Or maybe it works as well as a bandaid.??? Gotta show me some measurements or a side-by-side test before I'm convinced.??
For all of these reasons, and the fact that it's a cheap radio, and any mod activity introduces unknown risk (which is why regression testing exists), I think I'll save myself the trouble for now. ? I am still open to to the idea and interested to see if any more evidence comes in, in which case it's easy enough to add the zener.???? Or if I blow up this radio in which case you can give me a good Nelson "haha!"?? (Simpsons reference)
73,
Connie? W6EFI
Connie Stillinger
650-380-2018
On Friday, June 14th, 2024 at 10:37 AM, Doug Hendricks < ki6ds1@...> wrote:
Thank you Hiroki for your validation.? ?I heartedly encourage everyone who has usdx radios,? including the one from Ed Fong to do this simple mod.
-- Connie KN2EFI
|
Re: Protecting (tr)uSDX against high SWR
Connie,
I agree completely. What is the effect on the spectrum, particularly on SSB, which may easily be distorted due to the diode. I think that the failure mode is due to the high voltage as the 3 FETs can dissipate the couple of watts of reflected power.
It could also be neat fix if the diode is more or less transparent under normal operating conditions. It might be interesting to run an experiment with the diode biased with the peak operating voltage on the FETs using a VNA to see what its RF characteristics are in the HF bands. I have never seen an RF amp. that uses this kind of protection.
Dave W6VYC
On Friday, June 14, 2024 at 12:39:57 PM PDT, Connie W6EFI via groups.io <stillinger@...> wrote:
Is there a side-by-side test documented anywhere???? Ie, showing that the radio is destroyed without the zener diode under the same conditions otherwise??? I couldn't find one.?? They're cheap -- you'd think someone would love to blow one up for the views.
I've done a little searching and all I can find as the origin for this recommendation is just one guy with a self-assembled kit who blew his radio up in an unknown way with unknown power even though he had a tuner inline and was presumably tuned up, and he doesn't know what the root cause was, and then said he'd install the zener just in case.
As for WB2CBA (Barb), he just shows that his radio still works.? He didn't do a side-by-side test.??? And it's not a TruSDX.?? Maybe he could have painted it blue or stuck a bandaid to the back of the radio instead and shown that the radio still worked after a high-swr test.?? Look!?? Painting it blue works!
DL2MAN recommends against adding the zener.?? (His recommendation is boring, just use low power for tuning.? Personally I tune by ear before any kind of tx'ing.?? Works great if you have the ear and the tuner.) ?? Also I had a friend (sadly SK now) who gave his TruSDX a hard workout for a good while and told me that it was pretty robust against mismatch.
I don't think "voltage reflected back into the radio" is exactly the problem with mismatched impedances anyway so maybe the zener works, but maybe not for its breakdown threshold; maybe it just changes the tuning.?? Or maybe it works as well as a bandaid.??? Gotta show me some measurements or a side-by-side test before I'm convinced.??
For all of these reasons, and the fact that it's a cheap radio, and any mod activity introduces unknown risk (which is why regression testing exists), I think I'll save myself the trouble for now. ? I am still open to to the idea and interested to see if any more evidence comes in, in which case it's easy enough to add the zener.???? Or if I blow up this radio in which case you can give me a good Nelson "haha!"?? (Simpsons reference)
73,
Connie? W6EFI
Connie Stillinger
650-380-2018
On Friday, June 14th, 2024 at 10:37 AM, Doug Hendricks <ki6ds1@...> wrote:
Thank you Hiroki for your validation.? ?I heartedly encourage everyone who has usdx radios,? including the one from Ed Fong to do this simple mod.
--
Connie KN2EFI
|
Re: Is there a get together this Friday 6/28 at Baylands?
I think we doubled on Vern. I think I may have added him to the group. Maybe you should be the one who answers the requests.
Dave
On Tuesday, June 25, 2024 at 06:16:53 AM PDT, Verne Anderson via groups.io <verneanderson@...> wrote:
--
Verne Anderson W6LPM,
Thanks for showing interest in our group. Hope to see you at our Friday afternoon get togethers.
73, Dave W6VYC
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Thanks Connie and Chris for your advice. I neglected to mention that the laptop is running Windows 7; i found that indeed there is a rich selection of free apps for Windows and iOS drive wiping.?
Best, --David KM6RI
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Is there a get together this Friday 6/28 at Baylands?
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Verne Anderson W6LPM,
Thanks for showing interest in our group. Hope to see you at our Friday afternoon get togethers.
73, Dave W6VYC
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yes, mistyped. ?/dev/zero
On Mon, Jun 24, 2024 at 18:42, Christopher AI6KG < ch@...> wrote: If it's running Linux, you can just use dd if=/dev/null of=drivedevice
if=/dev/zero
?
73 de AI6KG
On Mon, Jun 24, 2024 at 6:38?PM Connie W6EFI via <stillinger= [email protected]> wrote: Look for a program called "zero" that will fill the disk with zeros. Or, Google for "zero out a hard drive" or some variant of that to get a big list of programs that will do the same thing.
If it's running Linux, you can just use dd if=/dev/null of=drivedevice
On Mon, Jun 24, 2024 at 18:07, David via < dkvarn@...> wrote: I have an ancient (c. 2009) HP-Compaq CQ-60 laptop that I am selling on eBay. I want to wipe the hard drive (not a SS drive) of my personal data. I am aware that simply deleting apps and files and defragging may not actually delete the data from the hard drive. Furthermore, there is a System Recovery partition that I understand can be used to restore deleted apps.
I thought of deleting the Recovery partition and filling the available space (about 190 GB) on the HD with movies, music etc. to overwrite any leftover data. Wondering if there are better methods... advice?
Thanks, --David KM6RI
--
Connie KN2EFI
--
Connie KN2EFI
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If it's running Linux, you can just use dd if=/dev/null of=drivedevice
if=/dev/zero??
?
73 de AI6KG On Mon, Jun 24, 2024 at 6:38?PM Connie W6EFI via <stillinger= [email protected]> wrote: Look for a program called "zero" that will fill the disk with zeros. ? Or, Google for "zero out a hard drive" or some variant of that to get a big list of programs that will do the same thing.
If it's running Linux, you can just use dd if=/dev/null of=drivedevice
On Mon, Jun 24, 2024 at 18:07, David via < dkvarn@...> wrote: I have an ancient (c. 2009) HP-Compaq CQ-60 laptop that I am selling on eBay. I want to wipe the hard drive (not a SS drive) of my personal data. I am aware that simply deleting apps and files and defragging may not actually delete the data from the hard drive. Furthermore, there is a System Recovery partition that I understand can be used to restore deleted apps.
I thought of deleting the Recovery partition and filling the available space (about 190 GB) on the HD with movies, music etc. to overwrite any leftover data. Wondering if there are better methods... advice?
Thanks, --David KM6RI
--
Connie KN2EFI
|
Look for a program called "zero" that will fill the disk with zeros. ? Or, Google for "zero out a hard drive" or some variant of that to get a big list of programs that will do the same thing.
If it's running Linux, you can just use dd if=/dev/null of=drivedevice
On Mon, Jun 24, 2024 at 18:07, David via groups.io < dkvarn@...> wrote: I have an ancient (c. 2009) HP-Compaq CQ-60 laptop that I am selling on eBay. I want to wipe the hard drive (not a SS drive) of my personal data. I am aware that simply deleting apps and files and defragging may not actually delete the data from the hard drive. Furthermore, there is a System Recovery partition that I understand can be used to restore deleted apps.
I thought of deleting the Recovery partition and filling the available space (about 190 GB) on the HD with movies, music etc. to overwrite any leftover data. Wondering if there are better methods... advice?
Thanks, --David KM6RI
--
Connie KN2EFI
|
Yes Paul, there is something called a lunastice (also called a standstill point). The Sun¡¯s standstill points occur at the solstices. The June solstice is the point in the orbit of the earth around the Sun where the Sun rises at its most northern point of the year. The Sun moves along a N-S axis and at the June solstice its rising point appears to stop and then reverse direction and begins moving southward. Sol sistere is latin for Sun stands still, hence, solstice.
So some loony astronomer decided that if the Sun has a solstice the Moon should have one too. I hadn¡¯t heard of this before but it does exist. It is the point at which the Moon reaches its farthest N and farthest S rising during a month (the word month comes from, guess which celestial object?). Should be spelled moonth.
But wait, there is more to this. The Moon goes through an 18.6 yr. cycle and the standstill point varies from 18.134¡ã(N or S) the major standstill and 28.725¡ã (N or S) the minor standstill. So a quick when does this occur? It occurs when the Moon's tilt with respect to the ecliptic is >=5¡ã so that the total apparent tilt of the Moon and Earth add to 28.5¡ã. The tilt of the Earth on its axis with respect to the celestial equator is ~23.5¡ã. It is just that this is occurring now until sometime into 2025.
Ain¡¯t you sorry that you asked :>)
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On Jun 20, 2024, at 5:46 PM, Paul AA6PZ < aa6pz@...> wrote:
On Thursday, June 20, 2024 at 02:51:29 PM PDT, Cliff Sojourner K6CLS via < cls@...> wrote:
Howard, thanks for this note.? It's exciting.? Love these long daylight days.
I've read we're coming up on a "lunastice" soon.? Apparent motion of lunar declination stops and reverses?? 18.6 year cycle?? Can you explain a little better?
Cliff K6CLS On June 20, 2024 1:51:02 PM PDT, HOWARD POMERANTZ < HOWPOM@...> wrote:
Today at 20:51 UTC (13:51 PDT) will be the June Solstice. The first day of summer. Day length here is ~14hrs 47min. which is the longest period between sunrise (05:45 PDT) and sunset (20:33 PDT) of the year.
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I have an ancient (c. 2009) HP-Compaq CQ-60 laptop that I am selling on eBay. I want to wipe the hard drive (not a SS drive) of my personal data. I am aware that simply deleting apps and files and defragging may not actually delete the data from the hard drive. Furthermore, there is a System Recovery partition that I understand can be used to restore deleted apps.
I thought of deleting the Recovery partition and filling the available space (about 190 GB) on the HD with movies, music etc. to overwrite any leftover data. Wondering if there are better methods... advice?
Thanks, --David KM6RI
|
Re: All in one solder gun
Howard,
Interesting.? ? Thanks,? Dave
On Monday, June 17, 2024 at 02:30:31 PM PDT, HOWARD POMERANTZ <howpom@...> wrote:
Hi Dave,
Here is the solder gun I mentioned on Friday. It is good for people who have mild tremors.
Here¡¯s the Amazon link. There are other brands available on eBay etc.
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David,
I will bring the Chameleon to Barry's on the 4th. I expect a full report on how it works (Hi, Hi). The cap doesn't look like an easy fix. I agree poor manufacturing quality.
Dave W6VYC
On Saturday, June 22, 2024 at 12:22:05 AM PDT, David via groups.io <dkvarn@...> wrote:
Chameleon makes a magloop that competes with Alpha's and is similarly priced. I surfed their web and found some pix... looks like they use the same plastic box as Alpha, rotated 90 degrees. Their variable cap looks the same as Alpha's except for possibly the reduction mechanism. From the pix It appears Chameleon's cap may have the same issue as Alpha's, possibly (and hopefully) not as severe--see pix.
It seems that even if the plates are not making contact, misalignment would reduce the power handling limit, due to increased potential for arcing.
Interesting... Best, --David KM6RI
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OMG 20M is hot! Worked France & many eastern US in first few mins. OTA with 100W. Best, --David KM6RI
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Chameleon makes a magloop that competes with Alpha's and is similarly priced. I surfed their web and found some pix... looks like they use the same plastic box as Alpha, rotated 90 degrees. Their variable cap looks the same as Alpha's except for possibly the reduction mechanism. From the pix It appears Chameleon's cap may have the same issue as Alpha's, possibly (and hopefully) not as severe--see pix.
It seems that even if the plates are not making contact, misalignment would reduce the power handling limit, due to increased potential for arcing.
Interesting... Best, --David KM6RI
|
I had used an AlexLoop (early version with LMR-400 resonator loop, owned by Vic) initially with great results. This addicted me to mag loops and I went for the Alpha thinking it was built better and therefore would be a better performer. It was better mechanically, but sadly not electrically due to the bug I documented.?
I am seeing about acquiring a lightly-used AlexLoop (current version) and will update shortly.
Best, --David KM6RI
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I sent another email to Steve during the wee hours Friday morning. By the time I got up I had received a memo for full electronic refund of purchase price and shipping and a PDF return mailing label. At least this part worked very well. Best, --David KM6RI
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I'm with Doug.? Who knows what else is wrong???
If this is for QRP portable, have you considered an AlexLoop? 73, Eric NF6S
ex WD6DBM
?
On Thu, Jun 20, 2024 at 7:13 PM, Doug Hendricks <ki6ds1@...> wrote: I would return for a full refund.? Who knows what else is wrong. I think they deserved a second chance but not a third.? Of course I have nothing invested, but that is what I would do.? Good luck and let us know what happens.? ?Doug
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And of course, PAARA will be operating at Bedwell Park, as usual.?
On Thu, Jun 20, 2024 at 6:12?PM Ned Tufekcic via <ntufekcic= [email protected]> wrote: Santa Clara County Amateur Radio Association - SCCARA?W6UW will have FD atThe American Red Cross
Southwest corner of N. 1st. St. and Plumeria
2731 North 1st St.
San Jose, CA 95134
We will provide BBQ (hot dogs, polish sausages?etc) for all visitors?and guests. You are welcome to join us to?operate the radios and enjoy the?BBQ. 73 Ned AC6YY
Isn't anyone else going to operate field day??
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... and that's the end of a great conversation.? Thanks, Paul!
On June 20, 2024 5:46:26 PM PDT, Paul AA6PZ <aa6pz@...> wrote:
On Thursday, June 20, 2024 at 02:51:29 PM PDT, Cliff Sojourner K6CLS via groups.io <cls@...> wrote:
Howard, thanks for this note.? It's exciting.? Love these long daylight days.
I've read we're coming up on a "lunastice" soon.? Apparent motion of lunar declination stops and reverses?? 18.6 year cycle?? Can you explain a little better?
Cliff K6CLS On June 20, 2024 1:51:02 PM PDT, HOWARD POMERANTZ <HOWPOM@...> wrote:
Today at 20:51 UTC (13:51 PDT) will be the June Solstice. The first day of summer. Day length here is ~14hrs 47min. which is the longest period between sunrise (05:45 PDT) and sunset (20:33 PDT) of the year.
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David W Crocker
David
Jeff Reagan
Cliff Sojourner K6CLS