Re: Alpha Amp Group Still Active??
Get a hold of glen, AE0Q.? He's active on both the QRZ amp group...and also the E-ham amp group....as well as other alpha experts.?
Glen answers all alpha e-mail issues everyday.
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Re: Need Help with Amp Supply LK500ZC
Especially the PLATE VOLTAGE meter it must measure 2400 to 3000 and decay to zero with the AC line power switched off.? Do NOT touch anything if it doesn’t work this way! ? One more thing – when you get to the part when you want to remove a tube be sure the plate cap off the tube you removed doesn’t touch the chassis and completely UNPLUG the AC power cord before opening it up. ? Mike N2LYM ? ? ?
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From: [email protected] [mailto:[email protected]] On Behalf Of Bob
Sent: Wednesday, November 29, 2023 9:16 PM
To: [email protected]
Subject: Re: [ham-amplifiers] Need Help with Amp Supply LK500ZC ? Verify that your meters are working correctly. ? Lou, Mike and all,
I turned it on and watched it with no drive.? At around 5 minutes the plates began turning red. See hopefully attached pictures.? I got no reading (0) on the plate and grid current meters.? I haven't yet tried removing the tubes.
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Re: Need Help with Amp Supply LK500ZC
Verify that your meters are working correctly. Bob W4JFA?
Lou, Mike and all,
I turned it on and watched it with no drive.? At around 5 minutes the plates began turning red. See hopefully attached pictures.? I got no reading (0) on the plate and grid current meters.? I haven't yet tried removing the tubes.
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Re: Need Help with Amp Supply LK500ZC
That tube is bad. Remove that tube and just try the other tube by itself to see what it does.
On Wednesday, November 29, 2023, 7:12 PM, John Roland <johnroland51@...> wrote: FWIW? Here are the pictures I intended to attach to my previous post.?? The top is after about 1 minute and bottom is at about 5 minutes.? No drive.? No meter readings.? Adrian I got your note and will try to work through your suggestions I am able to in the next few days.??? Thanks everyone.?? /John? W7SWB 
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Alpha Amp Group Still Active??
Anybody know whether there is an active Alpha amplifier group anywhere? I have a cupla questions about the AE9K monitor program for Alpha amps.
TNX,
Steve K0XP
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Re: Need Help with Amp Supply LK500ZC
FWIW? Here are the pictures I intended to attach to my previous post.?? The top is after about 1 minute and bottom is at about 5 minutes.? No drive.? No meter readings.? Adrian I got your note and will try to work through your suggestions I am able to in the next few days.??? Thanks everyone.?? /John? W7SWB 
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Re: Need Help with Amp Supply LK500ZC
Lou, Mike and all,
I turned it on and watched it with no drive.? At around 5 minutes the plates began turning red. See hopefully attached pictures.? I got no reading (0) on the plate and grid current meters.? I haven't yet tried removing the tubes.
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Re: Need Help with Amp Supply LK500ZC
Turn amp on and observe two things, as soon as?you turn it on look for your grid meter going negative and or the plate meter reading positive. ?Look for you tubes starting to gest up in a minute or two. ?If any of these happen report what you see. ?You may have developed a tube short or a loss of cut of bias. ?Report the findings here when you have them. Lou
On Tuesday, November 28, 2023, 11:43 PM, John Roland <johnroland51@...> wrote: Hi Everone,
I've owned this amp about 5 years but used very little. The amp was refurbished (new tubes, and relays) by a guy in north Idaho about 2017, just before I bought it. I have tried to contact him but get no response.
A couple weeks ago in the middle of a QSO I sensed some unusual heat from the amp and noticed the tubes were both cherry red. I shut it down immediately.? I have tuned it up a couple times since and the symptoms reoccur. ? I am (obviously) not an amp guy or much of a technician so I have 2 questions.? 1.? Is this a symptom of something that might be easily confirmed and repaired by me, ? and if not ? 2.?? Is there anyone in the Portland-Seattle-Vancouver BC area I might take it to for repair?
Thanks for any help or ideas
John
W7SWB
Does
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Re: Need Help with Amp Supply LK500ZC
Sounds like one of the 3-500s has a grid to cathode short. Remove them one at a time to find the bad one be VERY CAREFUL the plate meter is at zero before you touch anything. HV KILLS! ? 73 Mike N2LYM ? ? ?
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From: [email protected] [mailto:[email protected]] On Behalf Of John Roland
Sent: Tuesday, November 28, 2023 5:44 PM
To: [email protected]
Subject: [ham-amplifiers] Need Help with Amp Supply LK500ZC ? Hi Everone,
I've owned this amp about 5 years but used very little. The amp was refurbished (new tubes, and relays) by a guy in north Idaho about 2017, just before I bought it. I have tried to contact him but get no response.
A couple weeks ago in the middle of a QSO I sensed some unusual heat from the amp and noticed the tubes were both cherry red. I shut it down immediately.? I have tuned it up a couple times since and the symptoms reoccur. ? I am (obviously) not an amp guy or much of a technician so I have 2 questions.? 1.? Is this a symptom of something that might be easily confirmed and repaired by me, ? and if not ? 2.?? Is there anyone in the Portland-Seattle-Vancouver BC area I might take it to for repair?
Thanks for any help or ideas
John
W7SWB
Does
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Need Help with Amp Supply LK500ZC
Hi Everone,
I've owned this amp about 5 years but used very little. The amp was refurbished (new tubes, and relays) by a guy in north Idaho about 2017, just before I bought it. I have tried to contact him but get no response.
A couple weeks ago in the middle of a QSO I sensed some unusual heat from the amp and noticed the tubes were both cherry red. I shut it down immediately.? I have tuned it up a couple times since and the symptoms reoccur. ? I am (obviously) not an amp guy or much of a technician so I have 2 questions.? 1.? Is this a symptom of something that might be easily confirmed and repaired by me, ? and if not ? 2.?? Is there anyone in the Portland-Seattle-Vancouver BC area I might take it to for repair?
Thanks for any help or ideas
John
W7SWB
Does
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I have a 4cx1500B with 350 screen, 3500 volts plate. It does 3kw peak on SSB.? Its been run at 1500 with 2500 volts on plate for
4 years now.? Very important to have a negative and positive going screen meter so you can tune it properly.
The 4cx1500A is a completely different tube. Its directly heated, Has a huge Filament current of 40 amps, Tons of emission and is
flat out a beast of a tube.? Probably one of the most over looked.?
There is also a 5CX1500A that is pretty much the same as the 4cx1500 but has a suppressor grid that gets grounded.? Those tubes where
used in industrial generators and are fairly cheap.? A friend built an amp with this tube and it is incredibly clean. He has IMD down very low.
I have 6 of them with several sockets.? I plan to build a dual 5cx1500 amp for HF in the next year or so.? The cabinet, Roller and
other parts are all in the garage.?
C
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Hi guys. I found this on another site – interesting !
?
Regards,
?
John VK6JX
?
?
?
?
You had a weak 1500B.? Its a far better tube and for sure will make more power.? I have swapped these many times.
Rudi was clever. He had the socket centre pin modified to take the Eimac tubes and put a 6V tap on the transformer in the DX-2SP amplifier. I have tried both the 4CX1500B and the 4CX1000A in a friend's amp and the 4CX1000A is the much better choice. The
output with the 4CX1500B installed was quite a bit lower.
73, Alek VK6APK
On 26/11/2023 8:00 pm, Louis Parascondola via groups.io wrote:
If an amp uses FU728 by design and has an actual 728 socket stem, a 4cx1000 will not just fit in. The center shaft is too wide in diameter. ?It may be possible to enlarge the center hole on the 4cx1000 with
the right size drill bit to make it fit. ?The FU728 with a larger hole will fit a real 4cx1000 socket without an issue. ?Change filament voltage of course either way..
?
On Sunday, November 26, 2023, 6:49 AM, Adrian Fewster
<vk4tux@...> wrote:
Alek, see?
Can dropin for a FU-728 with filament voltage changed to 6v ..
73
vk4tux
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Hi guys. I found this on another site – interesting ! ? 
Regards, ? John VK6JX ? ? ?
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From: [email protected] <[email protected]> On Behalf Of W7WRX
Sent: Tuesday, November 28, 2023 1:24 AM
To: [email protected]
Subject: Re: [ham-amplifiers] CX1500? You had a weak 1500B.? Its a far better tube and for sure will make more power.? I have swapped these many times.
Rudi was clever. He had the socket centre pin modified to take the Eimac tubes and put a 6V tap on the transformer in the DX-2SP amplifier. I have tried both the 4CX1500B and the 4CX1000A in a friend's amp and the 4CX1000A is the much better choice. The output with the 4CX1500B installed was quite a bit lower. 73, Alek VK6APK On 26/11/2023 8:00 pm, Louis Parascondola via groups.io wrote: If an amp uses FU728 by design and has an actual 728 socket stem, a 4cx1000 will not just fit in. The center shaft is too wide in diameter. ?It may be possible to enlarge the center hole on the 4cx1000 with the right size drill bit to make it fit. ?The FU728 with a larger hole will fit a real 4cx1000 socket without an issue. ?Change filament voltage of course either way..
? On Sunday, November 26, 2023, 6:49 AM, Adrian Fewster <vk4tux@...> wrote: Alek, see?
Can dropin for a FU-728 with filament voltage changed to 6v ..
73
vk4tux
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OK. That's very encouraging. You could be right, as we had no
other 1500B tubes to compare it with.
Thanks, Alek.
On 28/11/2023 1:24 am, W7WRX wrote:
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You had a weak 1500B.? Its a far better tube and for sure will
make more power.? I have swapped these many times.
C
Rudi was clever. He had the socket centre pin modified to
take the Eimac tubes and put a 6V tap on the transformer in
the DX-2SP amplifier. I have tried both the 4CX1500B and the
4CX1000A in a friend's amp and the 4CX1000A is the much better
choice. The output with the 4CX1500B installed was quite a bit
lower.
73, Alek VK6APK
On 26/11/2023 8:00 pm, Louis
Parascondola via groups.io wrote:
If an amp uses FU728 by design and has
an actual 728 socket stem, a 4cx1000 will not just fit in. The
center shaft is too wide in diameter. ?It may be possible to
enlarge the center hole on the 4cx1000 with the right size
drill bit to make it fit. ?The FU728 with a larger hole will
fit a real 4cx1000 socket without an issue. ?Change filament
voltage of course either way..
On Sunday, November 26, 2023, 6:49 AM, Adrian Fewster
<vk4tux@...> wrote:
Alek, see?
Can dropin for a FU-728 with filament voltage changed to
6v ..
73
vk4tux
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If you run a drill bit into the base of a 4x1k or 4x1.5k to
enlarge the hole slightly, you'll also wind up grinding out that
dimpled keyway that aligns the tube with the notched socket shaft.
Of course, for a tube that's otherwise unusable, that's
mostly-inconsequential.
Steve, K0XP
On 11/26/2023 4:00 AM, Louis
Parascondola via groups.io wrote:
If an amp uses FU728 by design and has an actual 728 socket stem,
a 4cx1000 will not just fit in. The center shaft is too wide in
diameter. ?It may be possible to enlarge the center hole on the
4cx1000 with the right size drill bit to make it fit. ?The FU728
with a larger hole will fit a real 4cx1000 socket without an
issue. ?Change filament voltage of course either way..
On
Sunday, November 26, 2023, 6:49 AM, Adrian Fewster
<vk4tux@...> wrote:
Alek, see?
Can dropin for a FU-728 with filament voltage changed to 6v ..
73
vk4tux
--
See my QRZ.com page at
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You had a weak 1500B.? Its a far better tube and for sure will make more power.? I have swapped these many times.
C
toggle quoted message
Show quoted text
Rudi was clever. He had the socket centre pin modified to take the Eimac tubes and put a 6V tap on the transformer in the DX-2SP amplifier. I have tried both the 4CX1500B and the 4CX1000A in a friend's amp and the 4CX1000A is the much better choice. The
output with the 4CX1500B installed was quite a bit lower.
73, Alek VK6APK
On 26/11/2023 8:00 pm, Louis Parascondola via groups.io wrote:
If an amp uses FU728 by design and has an actual 728 socket stem, a 4cx1000 will not just fit in. The center shaft is too wide in diameter. ?It may be possible to enlarge the center hole on the 4cx1000 with the right size drill bit to
make it fit. ?The FU728 with a larger hole will fit a real 4cx1000 socket without an issue. ?Change filament voltage of course either way..
On Sunday, November 26, 2023, 6:49 AM, Adrian Fewster
<vk4tux@...> wrote:
Alek, see?
Can dropin for a FU-728 with filament voltage changed to 6v ..
73
vk4tux
|
Rudi was clever. He had the socket centre pin modified to take
the Eimac tubes and put a 6V tap on the transformer in the DX-2SP
amplifier. I have tried both the 4CX1500B and the 4CX1000A in a
friend's amp and the 4CX1000A is the much better choice. The
output with the 4CX1500B installed was quite a bit lower.
73, Alek VK6APK
On 26/11/2023 8:00 pm, Louis
Parascondola via groups.io wrote:
toggle quoted message
Show quoted text
If an amp uses FU728 by design and has an actual 728 socket stem,
a 4cx1000 will not just fit in. The center shaft is too wide in
diameter. ?It may be possible to enlarge the center hole on the
4cx1000 with the right size drill bit to make it fit. ?The FU728
with a larger hole will fit a real 4cx1000 socket without an
issue. ?Change filament voltage of course either way..
On
Sunday, November 26, 2023, 6:49 AM, Adrian Fewster
<vk4tux@...> wrote:
Alek, see?
Can dropin for a FU-728 with filament voltage changed to 6v ..
73
vk4tux
|
If an amp uses FU728 by design and has an actual 728 socket stem, a 4cx1000 will not just fit in. The center shaft is too wide in diameter. ?It may be possible to enlarge the center hole on the 4cx1000 with the right size drill bit to make it fit. ?The FU728 with a larger hole will fit a real 4cx1000 socket without an issue. ?Change filament voltage of course either way..
On Sunday, November 26, 2023, 6:49 AM, Adrian Fewster <vk4tux@...> wrote: Alek, see?
Can dropin for a FU-728 with filament voltage changed to 6v ..
73
vk4tux
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WTB: AL80,AL80A, SB1000 transformer
Looking for a good working transformer. ?Any one of the three. ?Send email direct to me , gudguyham@.... ?Thank you.
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Re: Coax to connect between exciter and SB-200
I'm wondering if a CM choke, right at he input of the xcvr might help ?? ?I have 2 x spare CM chokes....so? could put one at output of xcvr.... and 2nd one at input of amp.?
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Re: Coax to connect between exciter and SB-200
Jim,
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They are engraved plastic labels.
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Hal
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Bob
HaL Mandel