|
Hi Folks,
In the process of restoring a SR2K. In receive when I rotate the load control an oscillation / Chrip is heard on the speaker. This condition occur with or without HV.?
Thoughts Welcome,
dave
wa3gin
|
Chirp Chirp Chirp, geez.?
Hi Folks,
In the process of restoring a SR2K. In receive when I rotate the load control an oscillation / Chrip is heard on the speaker. This condition occur with or without HV.?
Thoughts Welcome,
dave
wa3gin
|
This is going to be a shorting load cap.? I just had this happen on one of my rigs. It would oscillate just exactly like you describe.
The Cap is a real sore spot of this rig.? They arc like crazy when people tune the rig at full power or with an antenna load that has some SWR.
This was documented in the papers on k9AXN website.
The document describes this problem and suggests manipulation of the three mounting screws.? Adjusting these has a huge impact on plate contact.?
What I suggest is to remove the cap and then clean and examine the plates.
Remove the three screws on side of chassis.? Use a flat screwdriver to slide the plastic coupler towards panel and off the cap shaft.??
Lean cap forward and you can get to the three solder tabs to unsolder the solid wire leads.
Once cap is out, you can get mag glass on and inspect the last section towards the rear.? I slid paper soaked in deoxit between plates and gently spun shaft to find where the plates where making contact.
If your LUCKY you can fix it.? If you can hipot test it, run it up to 600volts to make sure its fixed.
The one radio, I was able to repair it and gently bed the last few plates and eliminate?the contact and NOT even remove it.?
On the second radio the cap was just to far gone. The ball bearings had fallen out and heavy contact was made damaging the plates.
I have two spare load caps but they are NOT identical.? I have a third on the way now and think this time I got the right part.
Your welcome to the old one if you decide you can repair it. Maybe parts from it will help you.
Report back!
C
toggle quoted message
Show quoted text
Chirp Chirp Chirp, geez.?
Hi Folks,
In the process of restoring a SR2K. In receive when I rotate the load control an oscillation / Chrip is heard on the speaker. This condition occur with or without HV.?
Thoughts Welcome,
dave
wa3gin
|
Thanks for the info.? I read the AXN info, looked at the cap but didn't see anything.? I guess I will take a harder look.??
73 dave
On Tue, Apr 2, 2024 at 7:48?PM W7WRX < clark@...> wrote:
This is going to be a shorting load cap.? I just had this happen on one of my rigs. It would oscillate just exactly like you describe.
The Cap is a real sore spot of this rig.? They arc like crazy when people tune the rig at full power or with an antenna load that has some SWR.
This was documented in the papers on k9AXN website.
The document describes this problem and suggests manipulation of the three mounting screws.? Adjusting these has a huge impact on plate contact.?
What I suggest is to remove the cap and then clean and examine the plates.
Remove the three screws on side of chassis.? Use a flat screwdriver to slide the plastic coupler towards panel and off the cap shaft.??
Lean cap forward and you can get to the three solder tabs to unsolder the solid wire leads.
Once cap is out, you can get mag glass on and inspect the last section towards the rear.? I slid paper soaked in deoxit between plates and gently spun shaft to find where the plates where making contact.
If your LUCKY you can fix it.? If you can hipot test it, run it up to 600volts to make sure its fixed.
The one radio, I was able to repair it and gently bed the last few plates and eliminate?the contact and NOT even remove it.?
On the second radio the cap was just to far gone. The ball bearings had fallen out and heavy contact was made damaging the plates.
I have two spare load caps but they are NOT identical.? I have a third on the way now and think this time I got the right part.
Your welcome to the old one if you decide you can repair it. Maybe parts from it will help you.
Report back!
C
Chirp Chirp Chirp, geez.?
Hi Folks,
In the process of restoring a SR2K. In receive when I rotate the load control an oscillation / Chrip is heard on the speaker. This condition occur with or without HV.?
Thoughts Welcome,
dave
wa3gin
|
yes. The plates are shorting.? ?This radio was shorting on the back section. About 2 to 3 plates in.? I could set it so the rig was oscillating, then, using a plastic tool, spread the plates and noise would stop when I found it.
Also, I highly recommend you loosen the mounting screws while its in that spot.? It could be shimmed and fixed that way if the cap is not damaged.
C
toggle quoted message
Show quoted text
Thanks for the info.? I read the AXN info, looked at the cap but didn't see anything.? I guess I will take a harder look.??
73
dave
On Tue, Apr 2, 2024 at 7:48?PM W7WRX < clark@...> wrote:
This is going to be a shorting load cap.? I just had this happen on one of my rigs. It would oscillate just exactly like you describe.
The Cap is a real sore spot of this rig.? They arc like crazy when people tune the rig at full power or with an antenna load that has some SWR.
This was documented in the papers on k9AXN website.
The document describes this problem and suggests manipulation of the three mounting screws.? Adjusting these has a huge impact on plate contact.?
What I suggest is to remove the cap and then clean and examine the plates.
Remove the three screws on side of chassis.? Use a flat screwdriver to slide the plastic coupler towards panel and off the cap shaft.??
Lean cap forward and you can get to the three solder tabs to unsolder the solid wire leads.
Once cap is out, you can get mag glass on and inspect the last section towards the rear.? I slid paper soaked in deoxit between plates and gently spun shaft to find where the plates where making contact.
If your LUCKY you can fix it.? If you can hipot test it, run it up to 600volts to make sure its fixed.
The one radio, I was able to repair it and gently bed the last few plates and eliminate?the contact and NOT even remove it.?
On the second radio the cap was just to far gone. The ball bearings had fallen out and heavy contact was made damaging the plates.
I have two spare load caps but they are NOT identical.? I have a third on the way now and think this time I got the right part.
Your welcome to the old one if you decide you can repair it. Maybe parts from it will help you.
Report back!
C
Chirp Chirp Chirp, geez.?
Hi Folks,
In the process of restoring a SR2K. In receive when I rotate the load control an oscillation / Chrip is heard on the speaker. This condition occur with or without HV.?
Thoughts Welcome,
dave
wa3gin
|
Thanks,
I sprayed a piece of construction paper w/Deoxit and cleaned all 3 sections of fins... Prior to cleaning I could not find any visible shorts.? With the radio powered off I measured the resistance across the plates and found no shorts, just a constant 52 ohms.? After the cleaning and shaft bearing lube the chirp duration and amplitude dropped significantly. ALmost undetectable, buried in the noise of the TR relay. The -91vdc bias is on those plates all the time, even in receive?mode. The stator?sections appear to be press fitted or else I would attempt to shift them slightly. The spacing seems ridiculously?close. I don't have a shield on the 12BY7 and wonder if this in some way contributes to this instability issue.
Lastly, I've never been able to achieve the -20 / -30vdc bias indicated in the schematic of the PS-2000. It is more like -54 / -77vdc. Has anyone found similar readings?? The -91 vdc bias is rock solid in both low and high power. As is the .2A plate idle current.?
73 dave wa3gin
On Wed, Apr 3, 2024 at 12:55?PM W7WRX < clark@...> wrote:
yes. The plates are shorting.? ?This radio was shorting on the back section. About 2 to 3 plates in.? I could set it so the rig was oscillating, then, using a plastic tool, spread the plates and noise would stop when I found it.
Also, I highly recommend you loosen the mounting screws while its in that spot.? It could be shimmed and fixed that way if the cap is not damaged.
C
Thanks for the info.? I read the AXN info, looked at the cap but didn't see anything.? I guess I will take a harder look.??
73
dave
On Tue, Apr 2, 2024 at 7:48?PM W7WRX < clark@...> wrote:
This is going to be a shorting load cap.? I just had this happen on one of my rigs. It would oscillate just exactly like you describe.
The Cap is a real sore spot of this rig.? They arc like crazy when people tune the rig at full power or with an antenna load that has some SWR.
This was documented in the papers on k9AXN website.
The document describes this problem and suggests manipulation of the three mounting screws.? Adjusting these has a huge impact on plate contact.?
What I suggest is to remove the cap and then clean and examine the plates.
Remove the three screws on side of chassis.? Use a flat screwdriver to slide the plastic coupler towards panel and off the cap shaft.??
Lean cap forward and you can get to the three solder tabs to unsolder the solid wire leads.
Once cap is out, you can get mag glass on and inspect the last section towards the rear.? I slid paper soaked in deoxit between plates and gently spun shaft to find where the plates where making contact.
If your LUCKY you can fix it.? If you can hipot test it, run it up to 600volts to make sure its fixed.
The one radio, I was able to repair it and gently bed the last few plates and eliminate?the contact and NOT even remove it.?
On the second radio the cap was just to far gone. The ball bearings had fallen out and heavy contact was made damaging the plates.
I have two spare load caps but they are NOT identical.? I have a third on the way now and think this time I got the right part.
Your welcome to the old one if you decide you can repair it. Maybe parts from it will help you.
Report back!
C
Chirp Chirp Chirp, geez.?
Hi Folks,
In the process of restoring a SR2K. In receive when I rotate the load control an oscillation / Chrip is heard on the speaker. This condition occur with or without HV.?
Thoughts Welcome,
dave
wa3gin
|
On My rig if you turned the load knob it would vary the chirp.? It was worse when the plates made contact.? ?
Did you try to loosen the mounting screws while listing to the chirp?
Yes. The plates are super close. I think this is a major design flaw of this rig.? Those load caps should never have been used in a 1kw rig.?
toggle quoted message
Show quoted text
Thanks,
I sprayed a piece of construction paper w/Deoxit and cleaned all 3 sections of fins... Prior to cleaning I could not find any visible shorts.? With the radio powered off I measured the resistance across the plates and found no shorts, just a constant 52
ohms.? After the cleaning and shaft bearing lube the chirp duration and amplitude dropped significantly. ALmost undetectable, buried in the noise of the TR relay. The -91vdc bias is on those plates all the time, even in receive?mode. The stator?sections appear
to be press fitted or else I would attempt to shift them slightly. The spacing seems ridiculously?close. I don't have a shield on the 12BY7 and wonder if this in some way contributes to this instability issue.
Lastly, I've never been able to achieve the -20 / -30vdc bias indicated in the schematic of the PS-2000. It is more like -54 / -77vdc. Has anyone found similar readings?? The -91 vdc bias is rock solid in both low and high power. As is the .2A plate idle
current.?
73
dave
wa3gin
On Wed, Apr 3, 2024 at 12:55?PM W7WRX < clark@...> wrote:
yes. The plates are shorting.? ?This radio was shorting on the back section. About 2 to 3 plates in.? I could set it so the rig was oscillating, then, using a plastic tool, spread the plates and noise would stop when I found it.
Also, I highly recommend you loosen the mounting screws while its in that spot.? It could be shimmed and fixed that way if the cap is not damaged.
C
Thanks for the info.? I read the AXN info, looked at the cap but didn't see anything.? I guess I will take a harder look.??
73
dave
On Tue, Apr 2, 2024 at 7:48?PM W7WRX < clark@...> wrote:
This is going to be a shorting load cap.? I just had this happen on one of my rigs. It would oscillate just exactly like you describe.
The Cap is a real sore spot of this rig.? They arc like crazy when people tune the rig at full power or with an antenna load that has some SWR.
This was documented in the papers on k9AXN website.
The document describes this problem and suggests manipulation of the three mounting screws.? Adjusting these has a huge impact on plate contact.?
What I suggest is to remove the cap and then clean and examine the plates.
Remove the three screws on side of chassis.? Use a flat screwdriver to slide the plastic coupler towards panel and off the cap shaft.??
Lean cap forward and you can get to the three solder tabs to unsolder the solid wire leads.
Once cap is out, you can get mag glass on and inspect the last section towards the rear.? I slid paper soaked in deoxit between plates and gently spun shaft to find where the plates where making contact.
If your LUCKY you can fix it.? If you can hipot test it, run it up to 600volts to make sure its fixed.
The one radio, I was able to repair it and gently bed the last few plates and eliminate?the contact and NOT even remove it.?
On the second radio the cap was just to far gone. The ball bearings had fallen out and heavy contact was made damaging the plates.
I have two spare load caps but they are NOT identical.? I have a third on the way now and think this time I got the right part.
Your welcome to the old one if you decide you can repair it. Maybe parts from it will help you.
Report back!
C
Chirp Chirp Chirp, geez.?
Hi Folks,
In the process of restoring a SR2K. In receive when I rotate the load control an oscillation / Chrip is heard on the speaker. This condition occur with or without HV.?
Thoughts Welcome,
dave
wa3gin
|
The chirp is only for a nano second... it is not a oscillation?as you described. It's a blip chirp, haha.
I was able to adjust the PIN 3 bias? voltage down to factory specs by increasing the resistance of R328. I raised the resistance from 47K to 120K and every bias voltage, the -91, -20, -30 and the plate idle from Hi PWR and LO PWR are all right on the money now.
I'll have to think more about the blip chirp. Perhaps the RF choke to ground needs to be replaced or value changed. The 1Mh might not be doing the job.
73 dave
73 dave
On Wed, Apr 3, 2024 at 3:20?PM W7WRX < clark@...> wrote:
On My rig if you turned the load knob it would vary the chirp.? It was worse when the plates made contact.? ?
Did you try to loosen the mounting screws while listing to the chirp?
Yes. The plates are super close. I think this is a major design flaw of this rig.? Those load caps should never have been used in a 1kw rig.?
Thanks,
I sprayed a piece of construction paper w/Deoxit and cleaned all 3 sections of fins... Prior to cleaning I could not find any visible shorts.? With the radio powered off I measured the resistance across the plates and found no shorts, just a constant 52
ohms.? After the cleaning and shaft bearing lube the chirp duration and amplitude dropped significantly. ALmost undetectable, buried in the noise of the TR relay. The -91vdc bias is on those plates all the time, even in receive?mode. The stator?sections appear
to be press fitted or else I would attempt to shift them slightly. The spacing seems ridiculously?close. I don't have a shield on the 12BY7 and wonder if this in some way contributes to this instability issue.
Lastly, I've never been able to achieve the -20 / -30vdc bias indicated in the schematic of the PS-2000. It is more like -54 / -77vdc. Has anyone found similar readings?? The -91 vdc bias is rock solid in both low and high power. As is the .2A plate idle
current.?
73
dave
wa3gin
On Wed, Apr 3, 2024 at 12:55?PM W7WRX < clark@...> wrote:
yes. The plates are shorting.? ?This radio was shorting on the back section. About 2 to 3 plates in.? I could set it so the rig was oscillating, then, using a plastic tool, spread the plates and noise would stop when I found it.
Also, I highly recommend you loosen the mounting screws while its in that spot.? It could be shimmed and fixed that way if the cap is not damaged.
C
Thanks for the info.? I read the AXN info, looked at the cap but didn't see anything.? I guess I will take a harder look.??
73
dave
On Tue, Apr 2, 2024 at 7:48?PM W7WRX < clark@...> wrote:
This is going to be a shorting load cap.? I just had this happen on one of my rigs. It would oscillate just exactly like you describe.
The Cap is a real sore spot of this rig.? They arc like crazy when people tune the rig at full power or with an antenna load that has some SWR.
This was documented in the papers on k9AXN website.
The document describes this problem and suggests manipulation of the three mounting screws.? Adjusting these has a huge impact on plate contact.?
What I suggest is to remove the cap and then clean and examine the plates.
Remove the three screws on side of chassis.? Use a flat screwdriver to slide the plastic coupler towards panel and off the cap shaft.??
Lean cap forward and you can get to the three solder tabs to unsolder the solid wire leads.
Once cap is out, you can get mag glass on and inspect the last section towards the rear.? I slid paper soaked in deoxit between plates and gently spun shaft to find where the plates where making contact.
If your LUCKY you can fix it.? If you can hipot test it, run it up to 600volts to make sure its fixed.
The one radio, I was able to repair it and gently bed the last few plates and eliminate?the contact and NOT even remove it.?
On the second radio the cap was just to far gone. The ball bearings had fallen out and heavy contact was made damaging the plates.
I have two spare load caps but they are NOT identical.? I have a third on the way now and think this time I got the right part.
Your welcome to the old one if you decide you can repair it. Maybe parts from it will help you.
Report back!
C
Chirp Chirp Chirp, geez.?
Hi Folks,
In the process of restoring a SR2K. In receive when I rotate the load control an oscillation / Chrip is heard on the speaker. This condition occur with or without HV.?
Thoughts Welcome,
dave
wa3gin
|
Ok. Nice.? ?Sounds like you're making progress!? Both mine are on back burner now.? I have to wait for parts to resume work.? I get the new load cap first.? W0VMC made me one.? He took a slightly larger cap with the same mounting holes and machined the shaft
for me.? It was 3/8ths.? I measured everything so it should just drop in and be a slight upgrade.?
Would love to schedule a QSO when we get these things finished!
toggle quoted message
Show quoted text
The chirp is only for a nano second... it is not a oscillation?as you described. It's a blip chirp, haha.
I was able to adjust the PIN 3 bias? voltage down to factory specs by increasing the resistance of R328. I raised the
resistance from 47K to 120K and every bias voltage, the -91, -20, -30 and the plate idle from Hi PWR and LO PWR are all right on the money now.
I'll have to think more about the blip chirp. Perhaps the RF choke to ground needs to be replaced or value changed. The 1Mh might not be doing the job.
73
dave
73
dave
On Wed, Apr 3, 2024 at 3:20?PM W7WRX < clark@...> wrote:
On My rig if you turned the load knob it would vary the chirp.? It was worse when the plates made contact.? ?
Did you try to loosen the mounting screws while listing to the chirp?
Yes. The plates are super close. I think this is a major design flaw of this rig.? Those load caps should never have been used in a 1kw rig.?
Thanks,
I sprayed a piece of construction paper w/Deoxit and cleaned all 3 sections of fins... Prior to cleaning I could not find any visible shorts.? With the radio powered off I measured the resistance across the plates and found no shorts, just a constant 52
ohms.? After the cleaning and shaft bearing lube the chirp duration and amplitude dropped significantly. ALmost undetectable, buried in the noise of the TR relay. The -91vdc bias is on those plates all the time, even in receive?mode. The stator?sections appear
to be press fitted or else I would attempt to shift them slightly. The spacing seems ridiculously?close. I don't have a shield on the 12BY7 and wonder if this in some way contributes to this instability issue.
Lastly, I've never been able to achieve the -20 / -30vdc bias indicated in the schematic of the PS-2000. It is more like -54 / -77vdc. Has anyone found similar readings?? The -91 vdc bias is rock solid in both low and high power. As is the .2A plate idle
current.?
73
dave
wa3gin
On Wed, Apr 3, 2024 at 12:55?PM W7WRX < clark@...> wrote:
yes. The plates are shorting.? ?This radio was shorting on the back section. About 2 to 3 plates in.? I could set it so the rig was oscillating, then, using a plastic tool, spread the plates and noise would stop when I found it.
Also, I highly recommend you loosen the mounting screws while its in that spot.? It could be shimmed and fixed that way if the cap is not damaged.
C
Thanks for the info.? I read the AXN info, looked at the cap but didn't see anything.? I guess I will take a harder look.??
73
dave
On Tue, Apr 2, 2024 at 7:48?PM W7WRX < clark@...> wrote:
This is going to be a shorting load cap.? I just had this happen on one of my rigs. It would oscillate just exactly like you describe.
The Cap is a real sore spot of this rig.? They arc like crazy when people tune the rig at full power or with an antenna load that has some SWR.
This was documented in the papers on k9AXN website.
The document describes this problem and suggests manipulation of the three mounting screws.? Adjusting these has a huge impact on plate contact.?
What I suggest is to remove the cap and then clean and examine the plates.
Remove the three screws on side of chassis.? Use a flat screwdriver to slide the plastic coupler towards panel and off the cap shaft.??
Lean cap forward and you can get to the three solder tabs to unsolder the solid wire leads.
Once cap is out, you can get mag glass on and inspect the last section towards the rear.? I slid paper soaked in deoxit between plates and gently spun shaft to find where the plates where making contact.
If your LUCKY you can fix it.? If you can hipot test it, run it up to 600volts to make sure its fixed.
The one radio, I was able to repair it and gently bed the last few plates and eliminate?the contact and NOT even remove it.?
On the second radio the cap was just to far gone. The ball bearings had fallen out and heavy contact was made damaging the plates.
I have two spare load caps but they are NOT identical.? I have a third on the way now and think this time I got the right part.
Your welcome to the old one if you decide you can repair it. Maybe parts from it will help you.
Report back!
C
Chirp Chirp Chirp, geez.?
Hi Folks,
In the process of restoring a SR2K. In receive when I rotate the load control an oscillation / Chrip is heard on the speaker. This condition occur with or without HV.?
Thoughts Welcome,
dave
wa3gin
|
Dave Jordan