Ameritron Al811h Repair, Mods, Failed 200 Ohm Resistor, Penta 572b Tubes, 10 Meter Test

Added: 2026-04-30

[00:00:00]Hey everybody, amprepairgu.com.

[00:00:02]2038924119.

[00:00:05]That's 2038924119.

[00:00:09]Okay, so we have an Americanron AL811 here in for repair.

[00:00:16]This is a newer one. Has the resistor here, the 200 ohm resistor.

[00:00:21]They added this uh to help increase the the stability, but I've only seen problems with these burning up and they end up requiring more drive. Uh you know, when I'm done with one, I always test it on all bands. Works fine on 15 and 10. Uh yeah, we can't remove it if it has it in here because the micica cap values, some of the Mica cap values are different on one board versus an older board. You know, the older ones don't have the string of dodes. See the dodes to set the uh static plate current.

[00:01:01]So, the gain is a little bit higher in the tubes, which can cause instability issues.

[00:01:09]So, whenever I have one without the diodes, I always add them and I do the other stuff. Okay. So, I have a new resistor here. I'm going to install it. Make sure it's properly heat heat sunk to the chassis.

[00:01:24]I'm going to remove the metal oxide vari install the gas discharge tubes. I'll add one per side of the parallel filament. I'll install right down there.

[00:01:37]Also going to replace this braided material because it's really rigid. They the uh solder got sucked up into the strap. Makes it really rigid. So I always swap those and I'll put a longer screw in the base of the plate choke and also on the top of the plate choke and tighten up on hardware and do everything else I normally do. And I'll show it working on uh the upper one of the upper bands just to show you. So, uh, also has a broken anode cap. I don't know how that happened, but I will, uh, take care of that also.

[00:02:14]Okay, so I'm going to get to work. And also needs new SO239s. I already started unsoldering them, but they they have like no grip, so I always swap them out with brand new ones from Max Gain Systems. Um, if you watch my other videos, you'll see a lot of amps like SP220s that are older than me. The SO239s are still fine, but they just used cruddy connectors.

[00:02:41]So, okay. So, I'm going to get to work.

[00:02:50]I was looking around for a PL259, but as you can see, these just slip right in and out. There's no clip.

[00:02:57]I only do what's needed. I don't do extra stuff. I just do what's needed to get it fixed and to increase the per any mods to increase the performance for longevity, you know, but uh yeah. So, okay. So, I'm going to get to work. I'll see you guys soon. Stay tuned. Okay. So, the new resistor has been installed. I always put a light skim coat of thermal compound underneath it. Just enough to cover the surface. Just the thin thin layer. It's nice and tight. Everything soldered up nice. Nice. Here's the old one.

[00:03:42]See? Was smoking away. Customer said he could smell it. So, put that to the side and I'm going to get to work. Back to work. See you guys soon. We're back with the completed Americanron AL811.

[00:03:56]Okay. So customer wanted to see it working on 10 m. Radio is set to roughly 90 watts.

[00:04:06]Bird 43. 1KW slug. PP kit is on going into a bird dummy load. All genuine bird stuff.

[00:04:16]So that's the problem with this resistor. End up having to drive it a lot harder. And then I see a lot of times where the fite per permeability has changed and you know if someone especially if someone's doing a higher duty cycle mode you know and they get it hot and then you know ends up having to get swapped.

[00:04:37]So So I'm going to go ahead key the amp.

[00:04:40]Audio hello audio hello t 600 right there. 600 600 600 audio hello t works as it should. 600 600 the settings.

[00:04:51]Audio. Hello. Hello. Hello. Hello.

[00:04:53]Hello.

[00:04:55]Put it on. Play current. Audio. Hello.

[00:04:58]Hello. Hello. Hello. Hello. Hello.

[00:05:00]Hello. Hello. Hello. Hello. Hello.

[00:05:03]Audio. Hello. Hello. Hello. 600. 600.

[00:05:06]600. 600. 600. 600. 600. 600.

[00:05:11]Okay. So, all the other bands work. I'm going to shut it down. And with the high voltage bleed off, I'll unplug it, take the cover off, make sure there's no residual high voltage, and I'll show you everything I did. So stay tuned. See you guys soon. Please like, share, and subscribe.