On Dec 10, 2004, at 9:07 PM, Dan wrote:
Little mor eupdate..
i was wrong about hte transfomer taps the newer amp (the one I just
got) is wired for the factory 120 volts default and I get 1600 volts
the amp that I get more power out of is wired for 100 volts at the
transformer and gives me 1850 to 1900 volts. Could this be the
difference in output or the blackened tube?? I still wonder what
trouble i get into by swapping out the 811a between the two. actuall I
believe the older amp wired for 100 volts abd giving me 1900 volts
might actually be the one that should be changed to prevent early
death to the tubes.. manual says nominal 1700 volts///
The dead tubes I saw in an AL-811 were not offed by exceeding the 1500v
rating of 811As. Excessive anode-V and AØ tends to melt holes in the
811A's puny 65w anodes Instead, these tubes died from broken filament
wires - even though the amplifier was not dropped. The amplifier in
question had been operating normally for about a half-hour when a pop
was heard and the filaments went dark.
anyway you guys are the experts most concerned abott he startup spark,
large power surge and smell but might that be due to sitting 2
yrs..It rusn fine now and seems to have power out but bot as much as
the other older amp
any and all ideas are appreciated.. thanks
Dan
----------------
Well I received the amp looks really clean inside and out.. checked it
all out very close.. one of the tbes appears to be blackened in the
lower glass at one spot above the base. Does that mean anythign
important at this stage.
second question.. I decided to do the quick switch on and off to see
what happens.. man that was exciting.. flip switch on and amp lights
came on kinda loud spark and smell of sometign burit. also it took
such a chunk of power it rebooted my computers on the sam eline..
swichted it all off pulled plug took case off again.. did not see
anythign that might indicate anythign burnt etc.. still looks clean..
sooo being a brut for punishment I put the case back on and hit the
switch again. this time all seemed ok.. at least for about 10 secs
then a small pop and i could see a little arc at the vents near the 4
tubes. switched it off.. seemed ok so switched it back on (I know I
know).. anyway this time all was fine.. had on abt 1 hr no problems
voltage reads a little lower then my other 811H on same line this one
reads 1600 and the other reads 1800.. seems tapped same way..
anyway decide to try a small load into it works fine at least it
appears to.. now more questions.. It appears on the same exciter and
antenna I can not get quite the output that the other 811H gets..
where on the other I get 600 + on 20 meter with little drive seems
this only want to do about 450 or so.. can that be an indication that
the blackened tube is bad??
one more questions since I have the other 811H what problems would I
be causing if I swapped the 4 tubes form the other amp to this one? I
thought that may tell me if a new set of tubes woudl help twiththe
output of this amp.
Also.. any ideas about the start up problems sta6ed above?? it is
runngin right now stil showing only about 1600 volts but I have tested
it on 3 bands seems just fine just a little lacking in power output..
thanks for any suggestions.. I woud like ot hear opinions about
swapping the 4 811A form the know good amp to ths one for a est..
thanks
*********** REPLY SEPARATOR ***********
On 12/07/2004 at 10:06 PM Pat Poirier wrote:
Hi Dan,
If your amplifier that has been stored is only two years old, it
shouldn't
be a big deal to turn it on and just let it idle for several hours.
If the
amplifier was manufactured more than 5 years ago, I would use a
variable
AC
voltage transformer to bring the power up from low voltage to full
voltage
over a short time.
I would first start out by inspecting the power supply and making sure
that
there is nothing leaking or growing out of the electrolytics. If
there is
nothing and the amplifier isn't that old, I would turn it on and then
give
the tubes several hours just idling with no RF power to make sure that
they
are burned in and that they are not gassy. Then you should be all set
to
power it up.
73,
Pat W1KA
----- Original Message -----
From: "Dan" <dpipes@earthlink.net>
To: <Amps@contesting.com>
Sent: Tuesday, December 07, 2004 9:27 PM
Subject: Re[2]: [Amps] 811A - Tubes
Pat,
Thanks for the info. now you bring up another question. I have bought
another 811H thathas been stored for abotu 2 years. stored in a a
clean
dry closet inside plastic bags etc so it is very very clean.
might be a stupid question but... is there anythign i shold do or
maybe
NOT
do when I first fire it back up? Can sitting there for two years
actually
hurt the amp? i woudl think that some store stock could get stored
that
long or maybe warehouse stock..
Just curious this list has smoe real experts ,g. and I just do nto
want to
screw up a perfectly good amp by bringing it out of storage and maybe
doing
somethign wrong on re-start
thanks
Dan
*********** REPLY SEPARATOR ***********
On 12/07/2004 at 8:41 PM Pat Poirier wrote:
Hi Dan,
Don't bother spending the extra money on the Svetlana 811's. I had
four of
the white ceramic base Svetlana tubes in my AL-811H.
I purchased a matched quad from RF Parts of their Taylor Brand
811A's and
they were the same output that my Svetlana tubes were.
My AL-811H is used as a back up to my backup amplifiers and it is
very
seldom ever used except to turn it on for an hour or two idling to
keep
the
electrolytics formed every six months.
For $77.20 from RF Parts I don't think you can go wrong. Don't bother
looking at 572B's you will not see any more power and they are 2 1/2
times
the price.
Good Luck,
73,
Pat W1KA
----- Original Message -----
From: "Dan" <dpipes@earthlink.net>
To: <amps@contesting.com>
Sent: Tuesday, December 07, 2004 8:06 PM
Subject: [Amps] 811A - Tubes
I need 4 811 A tubes for my Ameritron 811H. I have read some say th
Russain
tubes are best some the centron etc.. What are the opinions and
where is
the
best place to buy a set of 4...
Thanks
Dan
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Richard L. Measures, AG6K, 805.386.3734. www.somis.org
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