| Author |
Message |
    
Creator
Member
Username: Creator
Post Number: 74
Registered: 1-2004
| | Posted on Wednesday, April 28, 2004 - 9:51 pm: | 
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Can someone explain to me what the Tune knob & Load Knob do on tube amps? Why doe some tube amps only have a tune knob not a load knob? How do you tune an amp? What does the load knob do? Is an amp without a load knob inferior? Is an amp with just a tune knob just as good as one with both knobs?
Thanks,
Creator |
Bruce
Senior Member
Username: Bruce
Post Number: 1200
Registered: 9-2003
| | Posted on Thursday, April 29, 2004 - 4:20 am: |
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tune knob "TUNES " the plate of the tube and " LOAD " loads ( tunes ) the antenna to match the plate of the tube ..... |
Jp1116
Junior Member
Username: Jp1116
Post Number: 49
Registered: 5-2002
| | Posted on Thursday, April 29, 2004 - 8:00 am: |
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I copied some of the instructions for a Palomar 300a. This would apply to an amp with a load and a tune knob on it. I would guess the manufacturer was trying to save a buck if they left one or the other out. I would check the tuning on both high and low, most amps need some fine tuning when switching power levels. If you change channels you might want to check the tuning again if you moved very far. It may still be close but check it at least the first time you move more than 10 channels or so just to see how it affects it. If you stay on the same channel you won't have to do this very often, just look at your watt meter to see if your output is where it belongs to be sure you didn't bump a knob and put it out of tune.
Set tune and load knob at 12 o'clock. Wait approximately 30 seconds before depressing mike button. Depress mike button and immediately adjust tune control for maximum meter reading. Now adjust load control for maximum meter reading.
NOTE: WHILE TUNING THE AMPLIFIER, DO NOT TRANSMIT FOR MORE THAN 30 SECONDS AT ONE TIME AS THIS WILL SHORTEN TUBE LIFE CONSIDERABLY.
It will be necessary to repeat the adjusting of the tune and load controls several times before maximum meter reading is obtained. The amplifier is now tuned for FM and SSB use. For AM use, the amplifier must be overcoupled; this is accomplished by taking the load control and turning clockwise 1/4 inch. If this is not done, the transmitted audio will sound "fuzzy" or distorted.
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Gezus306
Member
Username: Gezus306
Post Number: 53
Registered: 11-2003
| | Posted on Thursday, April 29, 2004 - 8:57 am: |
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" Tuning" an amp, less you could or would create
harmonics in the transmit mode via input to
the tubes and thier components.
In other words, if it were not " Tuned" properly, the amp and the freq creatted would NOT
be resonate. ( see study guide for HAM lisc. )
There you will also see how and why a tube
works and what must done in order for it to be used as a freq generator. ( I hope this helps ) |
Tech237
Moderator
Username: Tech237
Post Number: 5
Registered: 4-2004
| | Posted on Thursday, April 29, 2004 - 9:26 am: |
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Tuning an amp or radio brings the output stages into resonance for the frequency. THis is done so that spurious signals are reduced (hopefully to zero) and so that maximum powewr transfer can take place.
Bruce is right in saying that the TUNE control tunes the stages of the amplifier/radio to resonance and LOAD helps to match the output stages to the antenna for best power transfer.
NOTE: The LOAD control will not take the place of an antenna tuner if an antenna is far from resonant at the frequency used. |
Creator
Member
Username: Creator
Post Number: 76
Registered: 1-2004
| | Posted on Friday, April 30, 2004 - 1:52 am: |
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Thanks Everyone, much knowlege has been gained. ........... |
Tech833
Moderator
Username: Tech833
Post Number: 661
Registered: 8-2002
| | Posted on Tuesday, May 04, 2004 - 10:29 pm: |
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I have answered this in great detail many times. Do a search through the forum archives. |
