• You can now help support WorldwideDX when you shop on Amazon at no additional cost to you! Simply follow this Shop on Amazon link first and a portion of any purchase is sent to WorldwideDX to help with site costs.

ameritron al 811x

Oct 17, 2006
55
2
18
ALBERTA, CANADA
ive just got a new ameritron al 81x(export version 240 volts) and i want to change it to 120 volts. i have the manual here and it says i have to connect tap c to d,and e to f .my question is what will i use to connect this taps.? the one in there right now for 240volts looks shiny (not a copper???) and i cant tell. thanks in advance..........grasshopper1031
 

That 'strap' has to be conductive. After that, it's whatever you want to use. I would use the equivalent size to the existing 'strap'.
- 'Doc
 
ive got it switch to 120 volts now , didnt pop the fuse when i plug it in. reading 1700 HV on the meter.(specs around 1500-1700 as per manual ) so all is good so far. now my next question is,do i need to leave it on and how long (to "burn or "break in the new tubes.thanks again..........grasshopper1031(y)
 
tune for max smoke

sumthin tells me that ya better have a spare set of tubes handy:whistle:
 
811A's are a good tube but not very rugged. In the AL-811 series amps they are actually run at or beyond their limits under normal operation. Any attempts to get more out of the amp than the specs call for will result in shortened tube life. If you even consider operating AM mode with this amp be very carefull to keep the unmodulated carrier no more than about 100 watts for the three tuber and about 125 watts for the four tuber. The tubes just won't handle more than that in AM service without serious risk of overheating.
 
Replacing those 811's with 572's will work, but it will not work well without some modifications to the amplifier. Those modifications, plus those 572's, would finance several sets of 811's, so it's just not exactly the 'best' thing to do. The problem is that the 572's would not be running very efficiently at all, wrong plate voltage, for one thing. If you 'bump' that plate voltage to where it would be most efficient, you will also 'bump' the filament voltage to where it definitely should not be resulting in much shorter tube 'life'. If you can 'live' with the lesser output using those 'under volted' 572's they will certainly last much longer than the 811's will.
There are a few other thingys that will result with using those 572's. The characteristics of them being different from 811's means that the usual end points of the load and plate controls will change (dial settings). And, the resulting signal quality will decrease, sound sort of 'mushy'. It's just a lot better to run the 811's as they should be. (Been there, done that, learned the hard way.) The 'proof' being that Ameritron's AL-572 is NOT the same amplifier as the AL-811(any version).
- 'Doc

(That 'buck-boost' transformer used in the '811' series of amplifiers is a very handy thingy to have for it's intended purpose, but it is not a very good idea to use it as a 'booster' for output power. The results may be nice for a while, but there are consequences by doing it that way. The biggest draw-back is a pronounced increase in heat, which will eventually destroy the amplifier. I have a friend who found that by bumping the voltages with the 'buck-boost' transformer that the output of an AL-811H did increase. The problem was that the additional heat softened the tapped coil's bracing and it sort of 'bowed', almost touching other parts before he caught it. The fireworks display would have been spectacular!! So would have been the replacement cost.) ... wish he had taken pictures...
 
i'm a little confused by the term "al 81x" (export version),....

are we talking about a 3 hole al 811?
a 4 hole al 811h?
or something else?

if it's an 811h, then using 572-b's is about 50/50.

you won't get any more output (unless you drive the snot out of it), but you should get longer tube life if you do happen to accidently abuse the tube.;)

the limiting factor on the 811h is the POWER SUPPLY, not the plate dissipation value.

BTW: if you use 572-b's in the 811h, you only use (gasp!!!) 3 tubes. leave the hole next to the fan empty:pop:
 
i'm a little confused by the term "al 81x" (export version),...
The only difference i know of is the "X" model come`s with 10/12 meters enabled:

A simple modification will allow operation on frequencies above
15 meters. Instructions for this modification are available by
sending a written request for "Export Modification Instructions"
along with a copy of a valid amateur license. There is no charge
for this information. Export models are shipped with this
modification and have an "X" following the serial number

The AL-811 is a Three tube model
The Al-811-H is a Four tube model
The AL-811-HD Is a Four tube model using 572-B Tube`s in place of the 811-A`s

73
Jeff
 

dxChat
Help Users
  • No one is chatting at the moment.
  • dxBot:
    Tucker442 has left the room.
  • @ BJ radionut:
    LIVE 10:00 AM EST :cool:
  • @ Charles Edwards:
    I'm looking for factory settings 1 through 59 for a AT 5555 n2 or AT500 M2 I only wrote down half the values feel like a idiot I need help will be appreciated