ABC electronics inc.250 plus w/pics

[johnny9]

ahhh,more learning for me,thanks
that explains my luck with the first time trying to tune it.
this time i used all 3 to get the best reading on the meter and had no problem.

your comment now leads me to more questions,and learning,hope your ready lol.

i thought i had a 5 tube amp till your comment..now i understand more about the tubes and heres why.
you said 1 driving 3..well that made me understand the 6kv6 tube thats vertical,beside the 3 6jg6 horizontal tubes must be my driver tube.

and if i understood correctly the small 6bq5 tube in the rear corner is what makes it a 2 stage amp,and that tube keys up the amp ..

im feeling much smarter today than yesterday<gotproof>

 

[Captain Kilowatt]

Drive?? tunes the one tube "driver" into the three tube finals.



You have a two stage amplifier, the small tube is the keying tube.

I do not know if you have an input tune which would match the input of the driver stage to a decent VSWR, usually they are not in the smaller amplifiers and the input impedance is not very good.

:headbang DOH! You are right. I wasn't thinking about the built in driver stage in that amp. Some amps had an exciter tune control that I was thinking about.

 

[johnny9]

ok after lots of reading on this forum and many hrs online i think i have this tuning a tube amp down correctly in my head.
redneck engineering my way would read.

this is the basics;
to tune a tube amp with a drive,tune and load knob like on my amp,
with no more than 1-2 watts power from your radio to start.
turn drive down low.
turn tune to 12;00 position.
turn load to 12;00 position.
do these steps below as fast as poss to reduce hurting the amp.

with a low deadkey,"of course" key mic and adjust tune for max reading on watt meter.release mic.
wait a few seconds
then key mic and adjust load for max reading on watt meter.and release.
wait a few more seconds
then key mic and adjust drive for max reading on watt meter.
then re adjust tune and load again to make sure its still at max power on watt meter.
then when there all reading highest output you need to "dip the load"on the load knob..most folks dip the load clockwise,this means turning the load knob slightly till the meter moves a slight little bit off the max reading but not much.
this should put you right in the ball park of adjustment.then you may want to re adjust your radios deadkey to the specs of the amp for most amp output.

the drive knob is your drive adjustment for the driver tube in the amp thats driving the other tubes.

i read you can usually just reduce the drive knob to reduce the power a little if needed,without hurting the tune and load adjustment.i will be testing this soon with the meter and see for myself.

if you travel to different channels, much lower or higher than normal its a good idea to check adjustment on those channels and re adjust tune and load knobs for those channels.
and even better to make a cheat sheet to remember these adjustments so you dont have to put the strain of adjustment on the amp everytime.

there is much more to tube amps than i ever want to no so i hope i worded this right for others.

it was much more time for "me" to learn this than most because i didnt understand that "tune"is tuning the plate,and load,is loading the plate.
after reading about 12 different ways on tuning tube amps i "think"i understand better finally.
so if anything i said seems wrong please correct me so i can fix this redneck terminology, so other country boys and "not the sharpest tool in the shed" kinda guys/or gals may can use this thread**Jump_im**

 

[Johnnybgood]

The drive levels in watts of your radio, should always match the input of the amp you use. This may mean having the radio adjusted or a relay system made up with will switch in an antenuator to drop the radio's output to the required drive level on transmit and then bypass that antenuator on receive. If left inline, it could drop your receiver signals a bit, making distant stations harder to
hear.

 

[johnny9]

thats one thing i actually did understand.im not talking on the radio with the amp just yet, but i do listen everyday.
i def dont want to loose any reception as with my astroplane 15 ft to bottom and covered with trees on all sides i can hear cali,n.dakota,washington,coneticut,ohio and every state almost everyday real good at the right time..the superbowl on ch 6 is always rolling in the am and evening lol..i here so well i cant wait to get the tower up as i will prob be amazed then.
im in central fl btw.
not to mention i will be able to put the great info learned here to use and get the radio and amp in use..
im working on adjusting the midland today also with help from a thread on this forum..and great folks as always..
thanks for all your help and please jump in anytime to set me straight on things