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Hi everyone, ? I’m getting a “bypass SWR” on my la1k on 10, 12 and 15 meters.? Here is my configuration: ? 1.????? Yaesu FTDX-101MP 2.????? LA-1K 3.????? HF-Auto 4.????? MFJ 2990/2910 43’ vertical antenna. ? The Palstar troubleshooting guides says that there may be a loose connection or arcing.? If that is the case, why do I not get “bypass SWR” on any other band?? I replaced an Ameritron ALS-1300 amp with this amp and never had a problem with the old amp.? Is the LA-1K too sensitive or do I really have a problem?? BTW, I don’t have this problem on a dummy load or my OCF, which leads me to think it is an antenna problem.? Any comments or advice would be greatly appreciated. ? Best regards, Scott Sherer KC9WPS ?
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What does the SWR show on the antenna with a analyzer?
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I occasionally have this issue on 160m and I also run through an HF Auto, to a Cobra fed with window line and a 5KW balun at the shack entrance with 5' of LMR400 to the tuner.? ?I have the same exact issue as you, as do two other people with similar setups using non resonant antennas.? Im my case, although well grounded, I believe it is being caused by RF getting into the amp.? Since the high bands I use a resonant yagi I don't have any issues.? ?FWIW, the LA-1K in MY opinion, is entirely too sensitive to ultra short issues which, given the transistors used, would not even be a problem.? ?My solution, was to buy a M500 Ameritron amp to use on bands/antennas the LA-1K complains about.? ?I wish, once it was out of warranty, they would provide a way to set that SWR Bypass to 1/2 second or something besides kicking the amp out, and making you lose your contact.
Dave
N5GGG
OMISS NET
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Dave ...
I replied to Scott privately with the following:
Be sure you have the latest firmware version installed. ? About a year ago Palstar changed the way SWR is metered in the LA-1K and it is now incorporated in the current version listed on their website.
However, don't overlook antenna issues. ? High power brings out the worst in all of them. ? For example, it is now known that OCFDs, regardless of build, balun, or installation, are not suitable above 700-800 watts. ?At higher powers Common Mode Current is just too difficult to tame.
Solid state amps differ one from another and incorporate different power amplifier and transistor designs which makes comparing them for troubleshooting purposes difficult.
I had the same BYPASS SWR faults with my LA-1K. ?Many emails with Palstar and several trips to the backyard eventually produced success. ? Palstar did some firmware tweaking and I did some antenna tweaking. ? I think both were necessary. ?
After many years trying various OCFD designs, I currently use a homebrewed doublet fed with open wire line. ?While the feedline came off at a 90-degree angle, it wasn't entirely perpendicular to the radiators. ?Making it so and switching from 1-inch to 4-inch spreaders cured the LA-1K of its frequenting faulting.
That the LA-1K doesn't fault into a dummy load says a lot.
Good luck ... it's a great amp.
73,
Kent ?K9ZTV
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On Nov 27, 2021, at 9:42 AM, davenlr@... wrote:
?I occasionally have this issue on 160m and I also run through an HF Auto, to a Cobra fed with window line and a 5KW balun at the shack entrance with 5' of LMR400 to the tuner.? ?I have the same exact issue as you, as do two other people with similar setups using non resonant antennas.? Im my case, although well grounded, I believe it is being caused by RF getting into the amp.? Since the high bands I use a resonant yagi I don't have any issues.? ?FWIW, the LA-1K in MY opinion, is entirely too sensitive to ultra short issues which, given the transistors used, would not even be a problem.? ?My solution, was to buy a M500 Ameritron amp to use on bands/antennas the LA-1K complains about.? ?I wish, once it was out of warranty, they would provide a way to set that SWR Bypass to 1/2 second or something besides kicking the amp out, and making you lose your contact.
Dave
N5GGG
OMISS NET
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- I assume the HF-Auto finds an acceptable tuning solution on the problem bands?? If so, you might try tightening up the acceptable tuning solution range (which as I recall is factory set to 1.5:1 SWR).? Or alternately, you could try manually tuning to a "better" (lower) SWR and see if the Amplifier is happier.
- But if you actually have a bad cable / connection, the problem might only show up with power applied.? I remember reading one tip, where the author checks is cables by connecting them to a 12 volt DC power supply set to a high enough current to uncover a heating problem, but not enough to damage the cable (I'm thinking maybe 10 or 15A load).? I always suspect the user installed PL-259 connectors where it's all too easy to overheat and damage the dielectric material in the coax cable.
- You could take your Dummy Load outside and hook it up at the antenna feedpoint, which could then be useful to verify the cable is OK.
- If you have a RigExpert antenna analyzer (or a friend with one), some models include a TDR function (time domain reflectometer) which might spot a discontinuity on the cable run, along with it's approximate location (remember you must first set the coax cable's velocity factor to get a proper measurement readout).
Anyway, just some thoughts.
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Oh - as already suggested, you may have a common mode current problem getting back into the shack.? Common mode chokes are easily made if you can't "borrow" one for a quick test.? See the bottom of page 8 (Table 5) links in K9YC's A New Choke Cookbook:?
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I had an issue like this on 160m. What solved it for me was switching from LMR400 to LMR240. I had tried two different LMR400 (75') cables with the same SWR tripping on 160m When I switched to the LMR240 it stopped tripping.
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73,
Jerry
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What type of antenna? Test with dummy load. Using 75 ft. Into vertical RG-213.
On Sat, Nov 27, 2021, 12:20 PM Jerry Raia < JERRY@...> wrote: I had an issue like this on 160m. What solved it for me was switching from LMR400 to LMR240. I had tried two different LMR400 (75') cables with the same SWR tripping on 160m When I switched to the LMR240 it stopped tripping.
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73,
Jerry
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Sorry it is a 268' end fed with a 9 to 1 UNUN
73,
Jerry
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You couldn't have done any better. The following reference helped me several times.? There is a reference to VE3EED his information may be helpful to others interested in EFLW.? Presently 75 foot RG-213 to a CMC then 15 feet more of RG-213 to the vertical cured all of the issues of RF bouncing around in the shack. my CW key got me several times when the CMC was right at the antenna feed point. Diagram on my QRZ page. Only experience with EFLW, former antenna was 72 foot length at 35 feet high with a 4:1 unun. the 9:1 not so good. Both antennas worked well 160m - 10m. Hope you issue is resolved in short order.
On Sat, Nov 27, 2021 at 10:54 PM Jerry Raia < JERRY@...> wrote: Sorry it is a 268' end fed with a 9 to 1 UNUN
73,
Jerry
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<Be sure you have the latest firmware version installed. ? About a year ago Palstar changed the way SWR is metered in the LA-1K and it is now incorporated in the current version listed on their website.>
Thanks.? Yes, I updated.? I am on version 1.08C.
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Hi Jerry, 43’ vertical.? Dummy load works well, as does OCF.? Much thanks for your comments. ? Best regards, Scott KC9WPS ?
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From: [email protected] [mailto:[email protected]] On Behalf Of Jerry Repine
Sent: Saturday, November 27, 2021 4:34 PM
To: [email protected]
Subject: Re: [la1k] la1k issue, does anyone have any advice? ? What type of antenna? Test with dummy load. Using 75 ft. Into vertical RG-213. ? On Sat, Nov 27, 2021, 12:20 PM Jerry Raia <JERRY@...> wrote: I had an issue like this on 160m. What solved it for me was switching from LMR400 to LMR240. I had tried two different LMR400 (75') cables with the same SWR tripping on 160m When I switched to the LMR240 it stopped tripping.
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73,
Jerry
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Thanks so much, I will look into that! Happy holidays. ? Best regards, Scott KC9WPS ?
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From: [email protected] [mailto:[email protected]] On Behalf Of Jerry Raia
Sent: Saturday, November 27, 2021 2:20 PM
To: [email protected]
Subject: Re: [la1k] la1k issue, does anyone have any advice? ? I had an issue like this on 160m. What solved it for me was switching from LMR400 to LMR240. I had tried two different LMR400 (75') cables with the same SWR tripping on 160m When I switched to the LMR240 it stopped tripping.
--
73,
Jerry
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Thanks so much, Fred, I’m looking into that now.? Happy Holidays. ? Best regards, Scott KC9WPS ?
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From: [email protected] [mailto:[email protected]] On Behalf Of Fred, W9KEY
Sent: Saturday, November 27, 2021 2:11 PM
To: [email protected]
Subject: Re: [la1k] la1k issue, does anyone have any advice? ? Oh - as already suggested, you may have a common mode current problem getting back into the shack.? Common mode chokes are easily made if you can't "borrow" one for a quick test.? See the bottom of page 8 (Table 5) links in K9YC's A New Choke Cookbook:?
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Thanks so much Fred, I will be testing today. J ? Best regards, Scott KC9WPS ?
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From: [email protected] [mailto:[email protected]] On Behalf Of Fred, W9KEY
Sent: Saturday, November 27, 2021 2:05 PM
To: [email protected]
Subject: Re: [la1k] la1k issue, does anyone have any advice? ? - I assume the HF-Auto finds an acceptable tuning solution on the problem bands?? If so, you might try tightening up the acceptable tuning solution range (which as I recall is factory set to 1.5:1 SWR).? Or alternately, you could try manually tuning to a "better" (lower) SWR and see if the Amplifier is happier.
- But if you actually have a bad cable / connection, the problem might only show up with power applied.? I remember reading one tip, where the author checks is cables by connecting them to a 12 volt DC power supply set to a high enough current to uncover a heating problem, but not enough to damage the cable (I'm thinking maybe 10 or 15A load).? I always suspect the user installed PL-259 connectors where it's all too easy to overheat and damage the dielectric material in the coax cable.
- You could take your Dummy Load outside and hook it up at the antenna feedpoint, which could then be useful to verify the cable is OK.
- If you have a RigExpert antenna analyzer (or a friend with one), some models include a TDR function (time domain reflectometer) which might spot a discontinuity on the cable run, along with it's approximate location (remember you must first set the coax cable's velocity factor to get a proper measurement readout).
Anyway, just some thoughts.
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Thanks so much Kent, I will be going down your list today.? Happy holidays. ? Best regards, Scott KC9WPS ?
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From: [email protected] [mailto:[email protected]] On Behalf Of Kent Trimble, K9ZTV
Sent: Saturday, November 27, 2021 1:50 PM
To: [email protected]
Subject: Re: [la1k] la1k issue, does anyone have any advice?? I replied to Scott privately with the following: Be sure you have the latest firmware version installed. ? About a year ago Palstar changed the way SWR is metered in the LA-1K and it is now incorporated in the current version listed on their website. However, don't overlook antenna issues. ? High power brings out the worst in all of them. ? For example, it is now known that OCFDs, regardless of build, balun, or installation, are not suitable above 700-800 watts. ?At higher powers Common Mode Current is just too difficult to tame. Solid state amps differ one from another and incorporate different power amplifier and transistor designs which makes comparing them for troubleshooting purposes difficult. I had the same BYPASS SWR faults with my LA-1K. ?Many emails with Palstar and several trips to the backyard eventually produced success. ? Palstar did some firmware tweaking and I did some antenna tweaking. ? I think both were necessary. ? After many years trying various OCFD designs, I currently use a homebrewed doublet fed with open wire line. ?While the feedline came off at a 90-degree angle, it wasn't entirely perpendicular to the radiators. ?Making it so and switching from 1-inch to 4-inch spreaders cured the LA-1K of its frequenting faulting. That the LA-1K doesn't fault into a dummy load says a lot. Good luck ... it's a great amp. ?I occasionally have this issue on 160m and I also run through an HF Auto, to a Cobra fed with window line and a 5KW balun at the shack entrance with 5' of LMR400 to the tuner.? ?I have the same exact issue as you, as do two other people with similar setups using non resonant antennas.? Im my case, although well grounded, I believe it is being caused by RF getting into the amp.? Since the high bands I use a resonant yagi I don't have any issues.? ?FWIW, the LA-1K in MY opinion, is entirely too sensitive to ultra short issues which, given the transistors used, would not even be a problem.? ?My solution, was to buy a M500 Ameritron amp to use on bands/antennas the LA-1K complains about.? ?I wish, once it was out of warranty, they would provide a way to set that SWR Bypass to 1/2 second or something besides kicking the amp out, and making you lose your contact.
Dave
N5GGG
OMISS NET
|
Thanks Dave, Happy Holiday. ? Best regards, Scott KC9WPS ?
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From: [email protected] [mailto:[email protected]] On Behalf Of davenlr@...
Sent: Saturday, November 27, 2021 9:42 AM
To: [email protected]
Subject: Re: [la1k] la1k issue, does anyone have any advice? ? I occasionally have this issue on 160m and I also run through an HF Auto, to a Cobra fed with window line and a 5KW balun at the shack entrance with 5' of LMR400 to the tuner.? ?I have the same exact issue as you, as do two other people with similar setups using non resonant antennas.? Im my case, although well grounded, I believe it is being caused by RF getting into the amp.? Since the high bands I use a resonant yagi I don't have any issues.? ?FWIW, the LA-1K in MY opinion, is entirely too sensitive to ultra short issues which, given the transistors used, would not even be a problem.? ?My solution, was to buy a M500 Ameritron amp to use on bands/antennas the LA-1K complains about.? ?I wish, once it was out of warranty, they would provide a way to set that SWR Bypass to 1/2 second or something besides kicking the amp out, and making you lose your contact.
Dave
N5GGG
OMISS NET
|
Hi Dave, I do have the latest firmware.? I am on 1.08N.? ? Best regards, Scott KC9WPS ?
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From: [email protected] [mailto:[email protected]] On Behalf Of davenlr@...
Sent: Sunday, November 28, 2021 11:30 AM
To: [email protected]
Subject: Re: [la1k] la1k issue, does anyone have any advice? ? <Be sure you have the latest firmware version installed. ? About a year ago Palstar changed the way SWR is metered in the LA-1K and it is now incorporated in the current version listed on their website.>
Thanks.? Yes, I updated.? I am on version 1.08C.
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Fred, W9KEY
Jerry Raia
Jerry Repine