Re: Ameritron AL-80 (Not A or B)
Nick,it seems as though you may have a poor connection somewhere inside the realm of the tank circuit. ?This could be at the band switch, the connections of the coils to the variables or just about anywhere, so make sure of all mechanical and soldered connections. ?Above 4 meters there are no padding cap issues so it’s got to be something like that. ?Also be sure there is no slippage on any of the connections to the variable capacitor shafis! ?Good luck
On Sunday, December 10, 2023, 9:41 AM, Nick Jones KC0YKO <kc0yko@...> wrote: All,
Question for the group. I am working on an Ameritron AL-80 (not A or B). When tuning it up I run out of load. I max the load cap out at zero on all bands. (fully meshed/max capacitance). It behaves the same on a two different dummy loads so I believe it to be an issue with the amp. Before I add another doorknob across the load cap, I figured I would ask the group for other ideas.
--
73 Nick KC0YKO
|
Ameritron AL-80 (Not A or B)
All,
Question for the group. I am working on an Ameritron AL-80 (not A or B). When tuning it up I run out of load. I max the load cap out at zero on all bands. (fully meshed/max capacitance). It behaves the same on a two different dummy loads so I believe it to be an issue with the amp. Before I add another doorknob across the load cap, I figured I would ask the group for other ideas.
--
73 Nick KC0YKO
|
Re: Ten-Tec Centurion Parts Needed
“Although it’s a handsome looking amp it’s certainly not the best performer in its class. ?It lacks inductance on 160 and the tank isn’t so good on 15 and 10”. ? So true, Louis. As Jim VE7RF also told me, my Emtron DX-2SP had the exact same issues on the low bands, but especially on 15, 12 and 10m. After a few years of 1200-1500W FT8 operation, my 10m and 15/12m tank coil tap flexible soldered silver plated conductors were black and the two connections to the tank coil had gone…..bad. I re-made these two connections with 8mm flat silver plated copper conductor, held in place with tightening brass screws onto the tank coil and silver solder to make sure. Luckily, my band switch was unaffected by the high circulating currents. I added inductance on the toroidal tank inductor by moving the tap an additional 3 turns for 80m. This improved the efficiency up to around 60% (was below 40%) on 80m. Then I added some fixed loading capacitance on 160m which raised the efficiency on 160m from around 30% up to 50%. All of our Ham multi-band amps have these same problems, but they are solvable with a little help from the experts on here. ? My Emtron is now working well on all bands. ? Cheers, ? John VK6JX ?
toggle quoted message
Show quoted text
From: [email protected] <[email protected]> On Behalf Of Louis Parascondola via groups.io
Sent: Sunday, December 10, 2023 1:10 PM
To: [email protected]
Subject: Re: [ham-amplifiers] Ten-Tec Centurion Parts Needed? TenTec buit?their own variable capacitors. ?So their plates are unlike any others. ?I have some plates and if you want you?ship me the cap I’ll rebuild it for you. ?I should have a few plates left. ?Although it’s a handsome looking amp it’s certainly not the best performer in its class. ?It lacks inductance on 160 and the tank isn’t so hood on 15 and 10. ?
? On Saturday, December 9, 2023, 6:51 PM, Tom Hess <Tomhess8@...> wrote: I have a lot of parts for amplifiers and stuff. I handle estates for the local ham club and have? processed estates for several Collins Radio engineers. They collected lots of parts over the years. I don't have any experience with the Centurion, so I don't know what your parts look like. Please send a photo of the switch and specs?for the capacitor - size, value, voltage. ? On Sat, Dec 9, 2023 at 9:42?AM Omni <selcor@...> wrote: I have recently acquired a Ten-Tec Centurion model 422 that is in very nice condition, but has a blown up bandswitch and the plate tuning capacitor was arced.? I might be able to salvage the capacitor, but the bandswich will need to be rebuilt or replaced.? If anyone has a switch/parts and/or a capacitor please contact me off list to let me know what you have.
|
Re: Ten-Tec Centurion Parts Needed
TenTec buit?their own variable capacitors. ?So their plates are unlike any others. ?I have some plates and if you want you?ship me the cap I’ll rebuild it for you. ?I should have a few plates left. ?Although it’s a handsome looking amp it’s certainly not the best performer in its class. ?It lacks inductance on 160 and the tank isn’t so hood on 15 and 10. ?
On Saturday, December 9, 2023, 6:51 PM, Tom Hess <Tomhess8@...> wrote: I have a lot of parts for amplifiers and stuff. I handle estates for the local ham club and have? processed estates for several Collins Radio engineers. They collected lots of parts over the years. I don't have any experience with the Centurion, so I don't know what your parts look like. Please send a photo of the switch and specs?for the capacitor - size, value, voltage. Tom KD0HF On Sat, Dec 9, 2023 at 9:42?AM Omni < selcor@...> wrote: I have recently acquired a Ten-Tec Centurion model 422 that is in very nice condition, but has a blown up bandswitch and the plate tuning capacitor was arced.? I might be able to salvage the capacitor, but the bandswich will need to be rebuilt or replaced.? If anyone has a switch/parts and/or a capacitor please contact me off list to let me know what you have.
|
Re: Potter & Brumfield Sensitive Plate Circuit Relays
Hi ALL,
?
I have amongst my Henry Amps a 3K-A. (My 3K-A was manufactured in 1972 and still works well.)? It has the plate current relay in the B- lead to trip on over current above 1A.
?
?
5.2? ADJUSTMENT OF THE OVERLOAD RELAY
?
A low voltage, variable, metered DC supply of 1 amp is needed for this adjustment. The 3K-A should stay of f during this adjustment.
?
Connect the DC supply to the slider of R103 and to ground and increase the current of the supply to 1 amp.?? RYlOl should trip.?? If the relay does not trip, adjust
Rl03 until the relay trips at about 1 amp. When adjusting the overload relay, reset and check the overload current several times to get an average
setting.? RI03 should be about 3-4ohms.
?
If you download a copy of the 3K-A schematic and manual it explains how the relay works and how to calibrate the trip point.
?
In my opinion it would have been better served as a trip for the grid current.
?
Other amps and devices may have also used this method for protection.
?
?
73
?
Walt
KR4HV
?
|
Re: Ten-Tec Centurion Parts Needed
I have a lot of parts for amplifiers and stuff. I handle estates for the local ham club and have? processed estates for several Collins Radio engineers. They collected lots of parts over the years. I don't have any experience with the Centurion, so I don't know what your parts look like. Please send a photo of the switch and specs?for the capacitor - size, value, voltage. Tom KD0HF
On Sat, Dec 9, 2023 at 9:42?AM Omni < selcor@...> wrote: I have recently acquired a Ten-Tec Centurion model 422 that is in very nice condition, but has a blown up bandswitch and the plate tuning capacitor was arced.? I might be able to salvage the capacitor, but the bandswich will need to be rebuilt or replaced.? If anyone has a switch/parts and/or a capacitor please contact me off list to let me know what you have.
|
Re: Potter & Brumfield Sensitive Plate Circuit Relays
Thanks Steve. I do not any of the power supply, just the RF deck, but did work it and it pulls in at just under 22vdc
--
73 Nick KC0YKO
|
Re: Potter & Brumfield Sensitive Plate Circuit Relays
Thanks Chuck. I was clearly over complicating this just because I did not recognize the "plate circuit relay" terminology. You were correct, I rolled the variable power supply up and it pulled in at just under 22vdc
--
73 Nick KC0YKO
|
Re: Potter & Brumfield Sensitive Plate Circuit Relays
Hal, Thanks for the reply. I do not have the power supply, just the RF deck.?
--
73 Nick KC0YKO
|
Re: Potter & Brumfield Sensitive Plate Circuit Relays
Perhaps that relay was used in that application in an effort to
reduce the voltage/current to operate it to low values, such as
from a later-model (but older) transceiver with limited T/R relay
switching capability. Also, if there is a power supply used in the
amp for that relay, look at the output filter capacitor to get an
idea of the maximum voltage that was applied to operate the relay.
If that relay really is a "Sensitive Plate Circuit Relay", you
might find a miniature adjustment mounted on the armature by which
the actual sensitivity was adjusted. Sometimes, that adjustment
would have a very small indication plate on which the adjustment
range was mentioned in milliamperes.
If you apply power from an external adjustable power supply to
try to find what voltage/current used to actuate the relay, I
would first apply that power through an external current-limiting
resistor so as to limit the external voltage/current to something
most likely used to actuate the relay; otherwise, you could burn
out the relay coil very easily. Typically, such relays operated
with just a few milliamperes but as much as 10 - 30 VDC. That
"high" voltage was common because those relays were in the plate
circuits of receiving-type tubes passing only a few mils at a
hundred or more volts.
In the olden days, we hams used to use such relays to detect and
protect the sensitive screen or control grids of tubes from the
ravages of overcurrent. Less commonly, they could also be used to
detect overcurrent of cathode or plate current by connecting them
across resistive voltage dividers.
Steve,
K0XP
On 12/9/2023 9:06 AM, Nick Jones KC0YKO
wrote:
All, I have an old homebrew RF deck that the T/R rely is a Potter
& Brumfield LM11-2500. I can't find what the coil voltage is.
In the 1954 P&B catalog the LM series is titled?Sensitive
Plate Circuit Relays and only list coil resistance and pull MA
ratings. What was the typical application for a Sensitive Plate
Circuit Relay, and what voltage energized the coil? Not sure why I
am struggling to understand this but do not recognize the
Sensitive Plate Circuit Relay application. Thanks Nick
--
See my QRZ.com page at
|
Re: Potter & Brumfield Sensitive Plate Circuit Relays
Dear Nick,
?
My GUESS is the P&B magnet is 24 to 28 Vdc.
?
However, if you trace the wiring to the coil, back to
the power supply, you may there deduce the coil voltage by
energizing the xfmr primaries.
?
Hal
W4HBM
|
Re: Potter & Brumfield Sensitive Plate Circuit Relays
Years ago the coil of a plate circuit relay was in series with the plate of a vacuum tube set up to conduct at the pull in current when the tube was biased on.? Using ohms law, 0.009 A X 2500 ohms = 22.5V to “pull in” if you measured the voltage across the coil. ?Vacuum tubes were used just like transistors today to energize relays. ? -Chuck K1KW ?
toggle quoted message
Show quoted text
From: [email protected] [mailto:[email protected]] On Behalf Of Nick Jones KC0YKO
Sent: Saturday, December 09, 2023 12:06 PM
To: [email protected]
Subject: [ham-amplifiers] Potter & Brumfield Sensitive Plate Circuit Relays ? All, I have an old homebrew RF deck that the T/R rely is a Potter & Brumfield LM11-2500. I can't find what the coil voltage is. In the 1954 P&B catalog the LM series is titled?Sensitive Plate Circuit Relays and only list coil resistance and pull MA ratings. What was the typical application for a Sensitive Plate Circuit Relay, and what voltage energized the coil? Not sure why I am struggling to understand this but do not recognize the Sensitive Plate Circuit Relay application. Thanks Nick
|
Potter & Brumfield Sensitive Plate Circuit Relays
All, I have an old homebrew RF deck that the T/R rely is a Potter & Brumfield LM11-2500. I can't find what the coil voltage is. In the 1954 P&B catalog the LM series is titled?Sensitive Plate Circuit Relays and only list coil resistance and pull MA ratings. What was the typical application for a Sensitive Plate Circuit Relay, and what voltage energized the coil? Not sure why I am struggling to understand this but do not recognize the Sensitive Plate Circuit Relay application. Thanks Nick
|
Re: Alpha Amp Group Still Active??
Albany County Fasteners:
K9ER
Lowes have them for delivery!! Home Depot seems to be down here in UK this morning
Im sure some specialists would have them cheaper for mail order
When I am in the US on business I try and visit Home Dept and/or Lowes and have been surprised in recent visits about the availability of Metric parts and tools to the extent of buying some small sized long reach Metric sockets at a very good price, as well as small US screws for Drake kit and the like
73 Fred
toggle quoted message
Show quoted text
On Fri, Dec 8, 2023 at 06:19 AM, Steve wrote:
Actually, Adrian, I'm glad I didn't buy one of those, because finding
short M5 metric screws here in the back-country of the USA would have
been a real challenge 8-D
73,
Steve K0XP
On 12/7/2023 9:53 PM, Adrian Fewster wrote:
Great work Steve, This doorknob would have been a good fit ;
HVCT8G-10KV-DL60-802M 10KV 8000PF N4700 10 8000
20
60 15 20 M5 MURATA:DHS4E4A802KT2B
地方十多个饭店梵蒂冈梵蒂冈梵蒂冈反动个
73
vk4tux
On 8/12/23 15:39, Steve wrote:
I did resolve the problem I'd been having with my 8410. From time to
time, it would seem to fault; the HV would drop to zero after a few
seconds, and if you were watching when it happened, you'd notice the
plate current LEDS suddenly lite all the way to 1.5A before dropping
to zero. The curious thing to me was the LEDs would remain lit up;
yet, there was never a Fault LED. The blower would shut off
completely. This happened before I connected the amplifier to my
computer, so the amplifier was NOT getting power for the LEDs from my
USB line.
After awhile, I got around to examining things carefully, and finally
found this:
I wound up replacing those with six paralleled 1000 pF/10 kV discs,
spread out so they wouldn't arc to one another, and the amplifier has
been working fine since. I suspect the caps were blown due to
high-SWR events, one at a time. I was very surprised to find only six
kilovolt discs being used where the plate voltage was already half
the voltage rating of the cap leaving little margin for "mistakes".
TNX,
Steve K0XP
You receive all messages sent to this group.
View/Reply Online (#39723)
</g/ham-amplifiers/message/39723> | Reply To Group
<mailto:[email protected]?subject=Re:%20Re%3A%20%5Bham-amplifiers%5D%20Alpha%20Amp%20Group%20Still%20Active%3F%3F>
| Reply To Sender
<mailto:k0xp@...?subject=Private:%20Re:%20Re%3A%20%5Bham-amplifiers%5D%20Alpha%20Amp%20Group%20Still%20Active%3F%3F>
| Mute This Topic </mt/102884649/1015776> | New
Topic </g/ham-amplifiers/post>
Your Subscription
</g/ham-amplifiers/editsub/1015776> | Contact Group
Owner <mailto:[email protected]> | Unsubscribe
</g/ham-amplifiers/leave/12817456/1015776/1317925746/xyzzy>
[vk4tux@...]
--
See my QRZ.com page at *
|
Ten-Tec Centurion Parts Needed
I have recently acquired a Ten-Tec Centurion model 422 that is in very nice condition, but has a blown up bandswitch and the plate tuning capacitor was arced.? I might be able to salvage the capacitor, but the bandswich will need to be rebuilt or replaced.? If anyone has a switch/parts and/or a capacitor please contact me off list to let me know what you have.
|
Re: Alpha Amp Group Still Active??
Lowes have them for delivery!! Home Depot seems to be down here in UK this morning
Im sure some specialists would have them cheaper for mail order
When I am in the US on business I try and visit Home Dept and/or Lowes and have been surprised in recent visits about the availability of Metric parts and tools to the extent of buying some small sized long reach Metric sockets at a very good price, as well as small US screws for Drake kit and the like
73 Fred
toggle quoted message
Show quoted text
On Fri, Dec 8, 2023 at 06:19 AM, Steve wrote:
Actually, Adrian, I'm glad I didn't buy one of those, because finding
short M5 metric screws here in the back-country of the USA would have
been a real challenge? 8-D
73,
Steve K0XP
On 12/7/2023 9:53 PM, Adrian Fewster wrote:
Great work Steve,? This doorknob would have been a good fit ;
HVCT8G-10KV-DL60-802M??? 10KV 8000PF??? N4700??? 10??? 8000
20???
60??? 15??? 20??? M5??? MURATA:DHS4E4A802KT2B
地方十多个饭店梵蒂冈梵蒂冈梵蒂冈反动个
73
vk4tux
On 8/12/23 15:39, Steve wrote:
I did resolve the problem I'd been having with my 8410. From time to
time, it would seem to fault; the HV would drop to zero after a few
seconds, and if you were watching when it happened, you'd notice the
plate current LEDS suddenly lite all the way to 1.5A before dropping
to zero. The curious thing to me was the LEDs would remain lit up;
yet, there was never a Fault LED. The blower would shut off
completely. This happened before I connected the amplifier to my
computer, so the amplifier was NOT getting power for the LEDs from my
USB line.
After awhile, I got around to examining things carefully, and finally
found this:
I wound up replacing those with six paralleled 1000 pF/10 kV discs,
spread out so they wouldn't arc to one another, and the amplifier has
been working fine since. I suspect the caps were blown due to
high-SWR events, one at a time. I was very surprised to find only six
kilovolt discs being used where the plate voltage was already half
the voltage rating of the cap leaving little margin for "mistakes".
TNX,
Steve K0XP
You receive all messages sent to this group.
View/Reply Online (#39723)
</g/ham-amplifiers/message/39723> | Reply To Group
<mailto:[email protected]?subject=Re:%20Re%3A%20%5Bham-amplifiers%5D%20Alpha%20Amp%20Group%20Still%20Active%3F%3F>
| Reply To Sender
<mailto:k0xp@...?subject=Private:%20Re:%20Re%3A%20%5Bham-amplifiers%5D%20Alpha%20Amp%20Group%20Still%20Active%3F%3F>
| Mute This Topic </mt/102884649/1015776> | New
Topic </g/ham-amplifiers/post>
Your Subscription
</g/ham-amplifiers/editsub/1015776> | Contact Group
Owner <mailto:[email protected]> | Unsubscribe
</g/ham-amplifiers/leave/12817456/1015776/1317925746/xyzzy>
[vk4tux@...]
--
See my QRZ.com page at *
|
Re: Alpha Amp Group Still Active??
On 12/8/2023 1:10 PM, mike repinski via
groups.io wrote:
Did the caps short and put
high voltage on the antenna causing the amp meter to peg? Is
there a rf choke at the output connector?
As in any quality-designed-and-built power amplifier, yes, there
is a good-sized, large inductor from the output of the pi-network
to ground to guard against exactly this kind of failure mode.
What seems particularly impressive, in this case, is the fact
that when those caps arced over, they did not cause a BIG BANG, as
most of us might have expected. I never heard anything (but then
again, I don't hear much other than CW, anyway). Instead, the HV
simply rapidly drained off and the amplifier shut down (except for
the afore-mentioned logic power supply, which apparently kept the
front panel LEDs lit up although they never indicated what was
going on, let alone that a fault had just occurred).
This experience makes me hopeful that when the day comes that one
of the 4CX1000s flashes over (if ever), the amp will shut down
gracefully just like that instead of announcing the failure by
emulating a shotgun going off in my ear? 8-D? I've had my share of
those but no, that's not why I'm so deaf.
73,
Steve K0XP
|
Re: Alpha Amp Group Still Active??
On 12/8/2023 9:09 AM, Jim VE7RF wrote:
Those oem 220M? caps are each 2200 pf.? ( 6600 pf in total for all 3 of em in parallel).
Actually, they read "222M"; so it was clear they were 2200 pF. The actual correct component for plate blocking is a? 5 / 7.5 kv rated HT-50/58 sized doorknob.....and 2 are used in parallel...and work good on 160-10m.? ?These days, you can only get the HT-50/58 doorknob caps in 7.5 kv.? They will handle one helluva lot of current on upper HF....per the detailed specs in the HEC catalog. A 5 kV-rated cap is not likely to withstand 3 kV plate voltage under highly-mismatched circumstances at the legal power limit (such as your antler tuner arcing over during a wind storm). 7.5 kV is not much better, but better than 6 kV, obviously. The higher, the better. Here, with nearly 3 kV plate voltage, I wouldn't have designed in anything less than 10 kV; yet, Alpha put in those 6 kV-rated capacitors. I have been told that my failures are not the only ones that have been experienced in Alpha 8410s. The AL-1500 has a pair of HT-50 doorknobs but they're only 500 pF; 1000 pF is a capacitive reactance of only 88.4 ohms at 1.8 MHz, somewhat marginal IMHO at the legal limit. But W8-no-name apparently originally specified/dictated their use, unless he specified something larger, and then MFJ, in their ever-cheapening-mindset, reduced the original values to something more-affordable; so there they are. ?I have never seen a plate blocker blow up from high swr / no ant, open ant, shorted ant etc..at least not when using HT-50/58 sized caps.
I've "snapped" a 7.5 kV, 1000 pF doorknob years ago on an early 4-1000 amplifier at Ep=4500 volts; the body audibly cracked then arced internally during tuneup of the roller inductor. These days, I use my dwindling stash of the previously-widely-and-cheaply-available Russian monster-sized doorknobs VERY SPARINGLY, as who knows when, or whether, those will ever become available again? I had a handful of the 1000 pF/10 kV discs and decided this was as good a place as any to try them out as plate blocking caps. I wish I could rember where I bought them; but I know it was within the past several years. 73, Steve K0XP
|
Re: Alpha Amp Group Still Active??
Did the caps short and put high voltage on the antenna causing the amp meter to peg? Is there a rf choke at the output connector?
On Friday, December 8, 2023 at 01:19:46 AM EST, Steve <k0xp@...> wrote:
Actually, Adrian, I'm glad I didn't buy one of those, because
finding short M5 metric screws here in the back-country of the USA
would have been a real challenge? 8-D
73,
Steve K0XP
On 12/7/2023 9:53 PM, Adrian Fewster
wrote:
Great work Steve,? This doorknob would have been a good fit ;
HVCT8G-10KV-DL60-802M??? 10KV 8000PF??? N4700??? 10??? 8000???
20??? 60??? 15??? 20??? M5??? MURATA:DHS4E4A802KT2B
73
vk4tux
On 8/12/23 15:39, Steve wrote:
I did resolve the problem I'd been having with my 8410. From
time to time, it would seem to fault; the HV would drop to zero
after a few seconds, and if you were watching when it happened,
you'd notice the plate current LEDS suddenly lite all the way to
1.5A before dropping to zero. The curious thing to me was the
LEDs would remain lit up; yet, there was never a Fault LED. The
blower would shut off completely. This happened before I
connected the amplifier to my computer, so the amplifier was NOT
getting power for the LEDs from my USB line.
After awhile, I got around to examining things carefully, and
finally found this:
 ? 
I wound up replacing those with six paralleled 1000 pF/10 kV
discs, spread out so they wouldn't arc to one another, and the
amplifier has been working fine since. I suspect the caps were
blown due to high-SWR events, one at a time. I was very
surprised to find only six kilovolt discs being used where the
plate voltage was already half the voltage rating of the cap
leaving little margin for "mistakes".
TNX,
Steve K0XP
You receive all messages sent to this group.
View/Reply Online (#39723) | Reply To Group | Reply To Sender | Mute This Topic | New Topic
Your Subscription | Contact Group Owner | Unsubscribe [vk4tux@...]
--
See my QRZ.com page at
|
Re: Alpha Amp Group Still Active??
Those oem 220M? caps are each 2200 pf.? ( 6600 pf in total for all 3 of em in parallel).??
?
The problem with discs is..... current handling capability.? ?Upper HF will result in the highest RF current through a block cap.? And high duty cycle modes like? 10M FM,? ?data, rtty, FT-8? will stress em.
?
I bought some Ceramite brand 4700 pf @ 10 kv disc caps from Henry radio.? Then bought some Ceramite? 4700 pf disc caps, but this time in 15 kv, also from Henry radio.? ?Typ the higher voltage rated? disc caps also handle more current.
A few months back, I bought 3 x dozen? chinese? .01 uf (10,000 pf? or 103M)? rated at 30 kv....bought off their ebay site.? ?They came in 10-20-30 kv.? These 30 kv versions are monsters.... at 1.3" diam x 7/16" thick.? ?My hi-pot tester only goes as high as 15 kv.... and they draw 0 leakage current, even after 10 mins.... good enough.? ?They are cheap..and the shipping is dirt cheap.? ?The 11m ops use just one of the .01uf @ 20 kv versions for a coupling cap into the cathode of a GG high mu triode amp.
?
So far, so good....with my limiting experimenting.? These chinese discs handle a stupid amount of current.?
?
The pair of discs in the Drake? L7 ( also used for plate blocking)? ?are failure prone.
?
The actual correct component for plate blocking is a? 5 / 7.5 kv rated HT-50/58 sized doorknob.....and 2 are used in parallel...and work good on 160-10m.? ?These days, you can only get the HT-50/58 doorknob caps in 7.5 kv.? They will handle one helluva lot of current on upper HF....per the detailed specs in the HEC catalog.?
?
I have never seen a plate blocker blow up from high swr / no ant, open ant, shorted ant etc..at least not when using HT-50/58 sized caps.??
|
Nick Jones KC0YKO
Tom Hess
HaL Mandel