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

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.

I believe that the AE9K monitor program works only with the 8410 amplifier.? I have an 8100 and tried the program with it but was unable to establish communications.? I do have experience with using a terminal program such as Tera Term to talk to the 8100 over the USB connection to the amp, which creates a virtual serial port.? That's how you change the grid bias when you change tubes and it's how Alpha sets up the amp during manufacturing.

There are a couple of specialized Alpha groups here on groups.io.? There is one for the 87A and there was one other but don't recall which it was.? I usually use the Amplifier group on eHam and Glenn, AE0Q, responds to Alpha questions there.? Which Alpha(s) do you have?

73, Floyd - K8AC

On 11/30/2023 4:51 AM, Floyd - K8AC wrote:

There are a couple of specialized Alpha groups here on groups.io. There is one for the 87A and there was one other but don't recall which it was.? I usually use the Amplifier group on eHam and Glenn, AE0Q, responds to Alpha questions there.? Which Alpha(s) do you have?

Mine is the 8410.

TNX,

Steve K0XP

On 11/30/2023 5:17 AM, Adrian Fewster wrote:

On 30/11/23 22:51, Floyd - K8AC wrote:

I believe that the AE9K monitor program works only with the 8410 amplifier.? I have an 8100 and tried the program with it but was unable to establish communications.

?

I've already installed, and have been running, the program. But mine is running some 3 or 4 MINUTES behind the amplifier, and since I've seen nothing complaining about that, I'm wondering whether that's normal. That's almost like reading a book about the amp... "3 minutes 36.25 seconds ago, Alpha 8410 bandswitch=40 meters, 0 faults, Ip=2.453 amperes, Ig=0, Ep=340 volts ... "etc. etc..

TNX,

Steve K0XP

Strange.? When I access my 8100 via a USB port, it responds to commands from a terminal program instantly.? I wonder if you've tried accessing the 8410 from a terminal program???

On Wed, Nov 29, 2023 at 06:34 PM, Steve wrote:

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

There is an Alpha 9500 group HERE: /g/Alpha9500

Glenn, AE0Q posts/replies there often.


73,
Alan
W5ARM

开云体育

I asked to join the 9500 group a week or two ago, but never heard back. I did search the 87A group's archives and have seen Glenn post there. But I've never seen any discussion of any other amp other than the 87A on that group, so I'm very reluctant to join it, break protocol and bring up my 8410.

Besides, I doubt Glenn would be of much help as regards the AE9K 8410 monitor program.

And besides all that, 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

On Wed, Nov 29, 2023 at 06:34 PM, Steve wrote:

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

There is an Alpha 9500 group HERE: /g/Alpha9500

Glenn, AE0Q posts/replies there often.


73,
Alan
W5ARM

开云体育

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

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.??

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

开云体育

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

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

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