Upgrade Kit AL811 and AL811H amplifier
Copyright W8JI June 2021
Thank you for purchasing this kit (and/or modification manual). These kits and this technical manual are intended
to help fellow Hams understand potential failures. This technical instruction manual and these l kits allow
individuals to bring 811 series amplifiers up to latest revisions. Please order via email links on
https://
www.ctrengineeringinc.com
/ameritron-811-811h-upgrade-kits/
or email order query only to
This modification manual is also the result of feedback, questions, and suggestions by fellow Hams. More
suggestions are always welcome. The overriding philosophy is everything reasonably possible should be done to
prevent expensive or annoying damage, especially to expensive radios. An amplifier should work as well as possible
for the cost.
If you use this instruction manual without intention of making your own kit, please PayPal a payment gift of $10 to
[email protected]
These kits comes in two basic forms with one add-on:
(Power Supply rebuild) 811KS
1.) four better sized higher-voltage much longer-life 5000 hours 105c rated electrolytics
2.) four improved bleeder/equalizer resistors
3.) one large 6A grid meter protection diode
4.) four meter multiplier resistors. These resistors also correct a slight meter error
(Protection Kit) 811KP
1.) three application tested GDT tubes
2.) one large 6A meter protection diode
3.) one 100k 2 watt resistor
4.) two 3.9V 5 watt Zener diodes
5.)
10-ohm 9-watt CCS 10kV rated fault resistor
Add on part:
811R200K
200-ohm 25-watt non-inductive load resistor kit with hardware
Information in this modification manual is copyright 2021 by W8JI and CTR Engineering. I understand people like to
share things, but please remember we have several weeks’ labor composing this document. Please consider a
PayPal gift to
when using these instructions if you do your own kit.
Overview
I designed the AL811 series many years ago. It was intended to be a minimal cost reasonable power level
SSB and
CW only
amplifier. The initial design request was for just two tubes, but that obviously would have been
inadequate. As a result I added a third tube as a bare minimum cost amplifier, and pushed to have a better but still
not too expensive four-tube amplifier. The better version became the AL811H.
This instruction manual and the 811 kits are the result of direct feedback from servicing several dozens of
amplifiers. Read these instructions thoroughly before you start working on your amp. Make sure you understand
every step in order to avoid any trouble.
AL811
The three-tube 811 model is not neutralized. As with two unneutralized 572B tubes, three 811A tubes are
