I plan to be at the Baylands, starting with lunch. Hope to see many of you.
Hiroki AH6CY
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Hi .
Doug,
Glad to hear you are having fun chasing POTA!? I think POTA is a great boon for younger hams learning CW.? I chase POTA on occasion, and did one activation so far.? I had hoped to activate Lassen on my last chester trip, but the road was not yet plowed.? I'm currently chasing the K8K dxpedition, but like too many in the last years, it is nearly all FT8--not as much of a thrill as CW.
However, my Elecraft tuners come in handy where my 30m swr is 10:1, 12m at 7:1, and 17m at 5:1. :-)
Have fun! 73, Eric NF6S
ex WD6DBM
?
On Tue, Jul 2, 2024 at 7:12 PM, Doug Hendricks <ki6ds1@...> wrote: I have been? having a great time working Pota chasing Activators.? ?I have 32 states worked and 26 confirmed on Pota since June 5th.? All cw and 95% on 20m.? Using inverted L up 27ft and Chelegance vertical.? ?Both antennas work well.? It certainly has improved my cw and operating technique.? ?Rig has been KX2 and trusdx.? The more I use the Trusdx, the more I like it.? It has an excellent receiver and hears just as well as the KX2.? Sorry Eric, but it's true.? Of course the KX2 is old technology, it's over 10 years old I think.? Lol.? What are you guys doing on the air?? Doug
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I have been? having a great time working Pota chasing Activators.? ?I have 32 states worked and 26 confirmed on Pota since June 5th.? All cw and 95% on 20m.? Using inverted L up 27ft and Chelegance vertical.? ?Both antennas work well.? It certainly has improved my cw and operating technique.? ?Rig has been KX2 and trusdx.? The more I use the Trusdx, the more I like it.? It has an excellent receiver and hears just as well as the KX2.? Sorry Eric, but it's true.? Of course the KX2 is old technology, it's over 10 years old I think.? Lol.? What are you guys doing on the air?? Doug
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Re: LOTW UP Here is a copy of the email sent
I was just going to post that. Thanks.?
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MEMBER BULLETIN
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July 1, 2024
?
Dear ARRL member,
?
Effective 12:00pm ET / 16:00 UTC we will be returning Logbook of The World? (LoTW?) to service.
?
As work progressed on the network, some users encountered LoTW opening briefly during which some 6600 logs were uploaded. The logs were not processed until this weekend as we tested that the interfaces to LoTW were functioning properly.
We are taking steps to help manage what will likely be a huge influx of logs. We are requesting that if you have large uploads, perhaps from contests or from a DXpedition, please wait a week or two before uploading to give LoTW a chance to catch up. We have also implemented a process to reject logs with excessive duplicates. Please do not upload your entire log to ¡°ensure¡± your contacts are in LoTW as they will be rejected. Lastly, please do not call ARRL Headquarters to report issues you are having with LoTW. You can contact support at LoTW-help@....
?
Through the end of the year, you may experience planned times when LoTW will be unavailable. We have been using this time to evaluate operational and infrastructure improvements we would like to make to LoTW. Those times will be announced.
We appreciate your patience as we worked through the challenges keeping LoTW from returning to service. We know the importance of LoTW to our members, and to the tens of thousands of LoTW users who are not ARRL members. LoTW, just behind QST, is our second most popular ARRL benefit.
?
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Copyright ? 2024 American Radio Relay League, Incorporated. Use and distribution of this publication, or any portion thereof, is permitted for non-commercial or educational purposes, with attribution. All other purposes require written permission.
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Re: Protecting (tr)uSDX against high SWR
Thanks.? That explanation is what some of us were guessing.?
On Thursday, June 27, 2024 at 11:00:19 AM PDT, sittners <sittners@...> wrote:
Doug-
Attached is a rather lousy scan of the page but should be
sufficient. Let me know if you have any questions.
regards and 73
Phil, KD6RM
On 6/27/2024 9:30 AM, Doug Hendricks
wrote:
Could you please
post a picture of your quoted material?? I would love to read it.?
Thank you.? ?Doug
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Re: Protecting (tr)uSDX against high SWR
Thank you Phil.? ?It was perfectly readable and reaffirms my belief in adding the diode.? ?Thanks, Doug?
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Re: Protecting (tr)uSDX against high SWR
Doug-
Attached is a rather lousy scan of the page but should be
sufficient. Let me know if you have any questions.
regards and 73
Phil, KD6RM
On 6/27/2024 9:30 AM, Doug Hendricks
wrote:
toggle quoted message
Show quoted text
Could you please
post a picture of your quoted material?? I would love to read it.?
Thank you.? ?Doug
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Re: Protecting (tr)uSDX against high SWR
Could you please post a picture of your quoted material?? I would love to read it.? Thank you.? ?Doug
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CDC shortens official COVID quarantine guidance
Eric and all,
This is the latest re Covid quarantine.
Hiroki AH6CY
The nation is ¡°in a different place¡± with the COVID pandemic than it was four years ago, said Dr. Mandy Cohen, who directs the Centers for Disease Control and P¡
Source: PBS News
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Re: Protecting (tr)uSDX against high SWR
Hiroki-
The zener? protection diode is a common design practice and is
favored by Wes Hayward, W7ZOI. In his ARRL publication
"Experimental Methods..." he explains the design on 1.19, fig.
#1.35. subsequent design examples feature this design component.
Your experiments confirm the usefulness and utility of his
recommendation. Great job.
Phil
On 6/14/2024 8:42 AM, Hiroki Kato
wrote:
toggle quoted message
Show quoted text
I installed a Zenar diode to protect my (tr)uSDX
against high SWR and replicated the same experiment conducted by
Barb WB2CBA (the video I forwarded to this forum a while ago).
With a dummy load the (tr)uSDX shows 2.97 watt
output and SWR 1.1. Without the dummy load SWR shot up to 101.5
but no smoke or visible damage.?
The third photo shows how the diode was installed in
my XH2 (you remember the Poor Man¡¯s KH1?) which is made from a
Hi-band (tr)uSDX kit.
So I am totally convinced that a single Zenar diode
does protect your (tr)uSDX and other USDX radios.
Hiroki AH6CY
  
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I just found out I was exposed to covid either Friday or Saturday.? What is the current thinking on quarantine?? Needless to say, I won't make Baylands.? Again.? However, the batteries in my KX2 and KH1 are charged, so I got that going for me.? :-) 73, Eric NF6S
ex WD6DBM
?
On Wed, Jun 26, 2024 at 3:55 PM, David W Crocker via groups.io <dwcae@...> wrote:
I will be out of town this Friday, so see you next week..
Dave W6VYC
On Wednesday, June 26, 2024 at 11:22:48 AM PDT, Hiroki Kato <hiroki@...> wrote:
I will be at the Baylands starting with lunch.
Hiroki AH6CY
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Re: Protecting (tr)uSDX against high SWR
Doug and All,
I took a look at Steve's ATS-4 and Doug is correct there is a 47V zener diode across the FETS in the PA, so this has been used on simple CW amp. designs for some time. I still think that the uSDX+ design, using SSB, is a little more complicated than a straight CW amp.
Dave W6VYC
On Tuesday, June 25, 2024 at 05:41:14 PM PDT, David W Crocker via groups.io <dwcae@...> wrote:
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.
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Re: Protecting (tr)uSDX against high SWR
I also have a Q-Match manual tuner that has a tune mode with a resistive bridge that keeps the SWR below 2:1 under all load conditions. I agree, this type of tuner will protect these simple FET QRP finals.
Dave W6VYC
On Tuesday, June 25, 2024 at 06:15:17 PM PDT, HOWARD POMERANTZ <howpom@...> wrote:
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.
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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I will be out of town this Friday, so see you next week..
Dave W6VYC
On Wednesday, June 26, 2024 at 11:22:48 AM PDT, Hiroki Kato <hiroki@...> wrote:
I will be at the Baylands starting with lunch.
Hiroki AH6CY
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Re: Protecting (tr)uSDX against high SWR
I would like to do an infrared survey of the board and zener running into an infinite mismatch. If the power is going into the 1 Watt zener, it might be overheating. If some power is being dissipated elsewhere, I¡¯m curious about where else it might go.?
On Wed, Jun 26, 2024 at 12:56 PM Doug Hendricks via <ki6ds1= [email protected]> wrote: Connie.? Hiroki had 2 sets of finals burn out because he was operating into a high swr.? When he put the diode in the same radio, he was able to transmit for several minutes with no antenna attached and infinite swr.? There is your proof.? Without the diode and high swr, the radio? blew the finals.? Not once, but twice.? ?With the diode, the radio was protected when operating into even worse conditions.? ?What more do you need?????
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Re: Protecting (tr)uSDX against high SWR
Connie.? Hiroki had 2 sets of finals burn out because he was operating into a high swr.? When he put the diode in the same radio, he was able to transmit for several minutes with no antenna attached and infinite swr.? There is your proof.? Without the diode and high swr, the radio? blew the finals.? Not once, but twice.? ?With the diode, the radio was protected when operating into even worse conditions.? ?What more do you need?????
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Re: Protecting (tr)uSDX against high SWR
I would gladly trade a little power lost for protection, but I am not yet convinced that the diode actually provides protection.?
Show me a side-by-side test demonstrating that the radio is destroyed without the diode, but ?remains intact with the diode installed under otherwise identical conditions.
Testimonials and strongly asserted opinions don't have the same standing as experimental data.
Any mod activity introduces some risk ?not to mention time, effort, and materials, and now we have measurements showing that there is power loss associated with the mod. Show me data demonstrating the theoretical benefit is real it or I am going to put my efforts toward higher priority issues.
I will close with a reminder that I am NOT asserting that I will not blow up my trusdx at some point. I AM saying that no one is producing actual data, one way or the other. ? just theories along with some data showing that there is a downside. Show me the data and I will consider the mod.
On Wed, Jun 26, 2024 at 12:16, Doug Hendricks < ki6ds1@...> wrote: I have more data.? I measured the power out on the Trusdx with and without the diode protection.? ?Here is the data:
Band. W/diode. WO/diode. % lost
80.? ? ? ?5.96.? ? ? ? 6.35.? ? ? ? ? ?6.1
60.? ? ? ?5.00.? ? ? ? 5.19.? ? ? ? ? ?3.7
40.? ? ? ?5.27.? ? ? ? 5.59.? ? ? ? ? ?5.7
30.? ? ? ?5.38.? ? ? ? 5.60.? ? ? ? ? ?3.9
20.? ? ? ?5.35.? ? ? ? 5.52.? ? ? ? ? ?3.1
Voltage = 12.59V
The power lost ranged from .22W on 80m to .17W on 20m.? I will gladly trade that power loss for the protection and peace of mind.?
72, Doug?
--
Connie KN2EFI
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Re: Protecting (tr)uSDX against high SWR
It¡¯s possible that manufacturer(s) could retune the output circuit(s) to get that power back. We should tell them to add this zener.?
On Wed, Jun 26, 2024 at 12:16 PM Doug Hendricks via <ki6ds1= [email protected]> wrote: I have more data.? I measured the power out on the Trusdx with and without the diode protection.? ?Here is the data:
Band. W/diode. WO/diode. % lost
80.? ? ? ?5.96.? ? ? ? 6.35.? ? ? ? ? ?6.1
60.? ? ? ?5.00.? ? ? ? 5.19.? ? ? ? ? ?3.7
40.? ? ? ?5.27.? ? ? ? 5.59.? ? ? ? ? ?5.7
30.? ? ? ?5.38.? ? ? ? 5.60.? ? ? ? ? ?3.9
20.? ? ? ?5.35.? ? ? ? 5.52.? ? ? ? ? ?3.1
Voltage = 12.59V
The power lost ranged from .22W on 80m to .17W on 20m.? I will gladly trade that power loss for the protection and peace of mind.?
72, Doug?
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David W Crocker
Jeff Reagan