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Airplane1
Advanced Member
Username: Airplane1
Post Number: 639
Registered: 5-2004
| | Posted on Friday, November 18, 2005 - 6:40 pm: | 
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Hi techs,
found this on a radio forum and wanted to know what youb techs think of this tuning of tube amps. Does this sound lagit to you?
Hi All,
Dig around long enough and the answers come. I found a nice little link for those interested... And maybe a link that will save on those tubes of yours at the same time, whether they be Tubes in a KLV or an Ameritron or whatever else you may have.
Go to http://www.qsl.net/kk5dr/Tuneup.htm for the tune instructions for tube amps.
Although many amps do not have the meters of the more expensive amps... Everyone can benefit as long as they have some type of watt meter.
At the bottom you will see that it says after Maximum tune-up on AM take your load control and "Over Load" your amp... This will drop the dead key, you want to drop it 10% or so... Down at the bottom I give an example of my linears.
Make sure when you advance that Load control that you advance it in the direction that the Coupler "Un Meshes" itself... The easiest thing to do is take off your case and look.
This drops the Grid Current 30% to 50%... Thus promoting a much longer life expectancy of tubes! And along with it comes the swing that produces that great Audio punch!!
Example of the KLV 1000:
Texas Ranger Base Station= 1.5 Watt DeadKey/14 Watt Swing
150 Watts DeadKey= 692 Watts Swing (On Low)
550 Watts DeadKey=1525 Watts Swing (On High)
This is with a Bird Watt Meter and Svetlana Russian EL-509's
Since running like this the Case directly beneath the power supply has run much, much cooler... It's hard to give a number like that... But I'd say 40% Cooler than previous.
Also... Tuning the KLV the way the manual reccomends only produces, get this...
175 Watt DeadKey=550 Watts Swing
Same Tubes... Same Power Setting... Just not "Over Loading" the load control... Yet it's harder on the tubes...
This may be part of the reason for the dreaded tube failure experienced in the KLV ... I will know more later on as I use these linears and see for myself how these tubes hold up.
And to be quite honest... Now that I can swing so much on Low I may not use High power... I mean the audio punch is nothing short of phenomenal on this Amp!!
I wish I would have run into this a long, long time ago... But like anything else, live and learn.
Don't take my word for it... Try it yourself and see what happens.
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Patzerozero
Senior Member
Username: Patzerozero
Post Number: 1909
Registered: 7-2004
| | Posted on Friday, November 18, 2005 - 7:28 pm: |
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call svetlana technical at (415)233-0429 & ask about the output of THEIR EL509 high performance tetrodes. the mere suggestion of rmitaly's implying that 1400 watts PEP was possible had the gentleman in hysterics. his suggestion was that 500 watts was a more realistic output... |
Pogo12
Intermediate Member
Username: Pogo12
Post Number: 100
Registered: 3-2005
| | Posted on Monday, October 30, 2006 - 4:03 pm: |
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The reason to drop the deadkey is to allow for the extra power(grid current) that develops from your modulation.This keeps the grid current within the operating range of the tube.If you dont do this excess grid current develops causing distortion/splatter/weakens the tube and it can cause arching in the tank circuit.People that tune the load for max dont realize that they are tuning wrong.The amp should be tuned for max on the plate(tune)control only.This sets the output of the tube to the correct frequency.The load matches the amplifier to the antenna.Tune the load for max and then then back it off some.It will drop deadkey but you will have a cleaner signal and your tubes last longer.You get the power back in modulation. |
Bruce
Senior Member
Username: Bruce
Post Number: 4144
Registered: 9-2003
| | Posted on Monday, October 30, 2006 - 8:44 pm: |
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Pogo
You lost me ......
If your saying don't squeeze every drop of power out and give the tube a break i'll buy that. However if your driving the tube within its normal ratings with full drive it should be fine.
There are 2 ratings ICAS and CCS used ICAS is peddel to the medal .......and CCS is the tube was used by a little old ham only on sundays for copper net.
There is one more Us old VHF guys know and that was when WW2 tubes for 2 meters were cheep. Tubes like the 829b would give you 60 watts out all day with a 5 watt AM rig driving it ..... OR you could run it MY WAY .....by watching the white hot grid through the red hot plate .... untill it melted .....
Same goes for CB ..... |
Kid_vicious
Senior Member
Username: Kid_vicious
Post Number: 2225
Registered: 9-2004
| | Posted on Monday, October 30, 2006 - 10:49 pm: |
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he is referring to "overcoupling" the amp.
i have never tried it, but if have read about hams and CB'ers alike doing it to tube amps for a lotta years.
matt |
Bruce
Senior Member
Username: Bruce
Post Number: 4145
Registered: 9-2003
| | Posted on Tuesday, October 31, 2006 - 5:44 am: |
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OVERCOUPLING ......
O'my last time i had to play with that was with my HT-37 ..... |
Dxmodulator
Member
Username: Dxmodulator
Post Number: 78
Registered: 11-2004
| | Posted on Tuesday, October 31, 2006 - 9:35 am: |
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I overcouple my 300A every time I use it. That is the way you should tune all tube amps. When you hear guys on the DX who say auuuudddiiiooo, no doubt they are tuning that old tubber. First tune the amp with the dead key then overcouple the amp using the modulation from your voice saying aaauuudddiiiooo. |
Pogo12
Intermediate Member
Username: Pogo12
Post Number: 104
Registered: 3-2005
| | Posted on Saturday, November 04, 2006 - 9:20 pm: |
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You will hear some people tune with a whistle which really isnt the best way because they dont talk in the audio range of a whistle.It will work but its more overcoupling than you need.Like DX said tune in your own voice saying audio.If you have an amp with a amp meter on the face instead of a rf meter such as the d&a amps had you dont want to tune by that meter unless you have the instructions for the amp or you know what youre doing.That meter you donot tune for max output.its a current meter. |
Tech833
Moderator
Username: Tech833
Post Number: 1502
Registered: 8-2002
| | Posted on Sunday, November 05, 2006 - 11:15 am: |
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This thread is killing me.....
We have discussed the PROPER way to tune a tube amp in great detail. Can anyone find that thread?
Tuning the way suggested here explains why so many CBers and hams have amp and early tube failures. |
1861
Advanced Member
Username: 1861
Post Number: 590
Registered: 2-2004
| | Posted on Sunday, November 05, 2006 - 5:09 pm: |
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Paul , I,ve searched , but every thread I find has some different variations . Which thread are you referring to , because I would like to know the best way . |
Airplane1
Advanced Member
Username: Airplane1
Post Number: 918
Registered: 5-2004
| | Posted on Monday, November 06, 2006 - 8:27 am: |
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I want to see that thread too 833.
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Tech808
Moderator
Username: Tech808
Post Number: 12095
Registered: 8-2002
| | Posted on Monday, November 06, 2006 - 8:52 am: |
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Archived Messages
» 2004
» 04/01/2004 to 04/30/2004
» Tunning In A Tube Linear
---------------------------
Ask The Tech
» Amplifiers
» Tuning up a tube amp
---------------------------
Ask The Tech
» Amplifiers
» Tuning an old tube amp
---------------------------
Open Forum
» Archived Messages
» 2004
» 05/01/2004 to 05/31/2004
» Tube Amps (RM) Tune knob & Load Knob
And there are many more posts you can find by using the Search feature located under Utilities to the left of the forum here.
Hope this help's,
Lon
Tech808
CEF808
N9CEF
CVC#2 |
Mrclean
Junior Member
Username: Mrclean
Post Number: 44
Registered: 12-2003
| | Posted on Sunday, November 12, 2006 - 5:34 am: |
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On my Heathkit SB 200 I set dk 1/4 of the max swing im getting. Set load and tune for max swing and then use load and overload it till DK is 150. Swing 600 to 650 |
Caledonia
Junior Member
Username: Caledonia
Post Number: 20
Registered: 8-2005
| | Posted on Sunday, November 12, 2006 - 6:01 am: |
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I think the correct term for that is "overcouple". I have to do that to my KLV-400 in order to use it on AM. Tune and Load to max with deadkey, then turn load clockwise to bring carrier to 1:4 ratio. It works very well like that! |
Hollowpoint445
Senior Member
Username: Hollowpoint445
Post Number: 1408
Registered: 6-2004
| | Posted on Sunday, November 12, 2006 - 9:22 am: |
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Thanks for the link Lon. |
Hollowpoint445
Senior Member
Username: Hollowpoint445
Post Number: 1409
Registered: 6-2004
| | Posted on Sunday, November 12, 2006 - 9:52 am: |
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Here are some of Tech833's past comments regarding the tuning of tube amplifiers:
Tech833 - Posted on Saturday, December 28, 2002 - 8:13 pm:
http://www.copperelectronics.com/cgi-bin/discus4/board-auth.cgi?file=/34/6912.html
For maximum tube life, tune the plate tune control for lowest plate current, then the loading control for the amount of power you want. Then, finish up by retuning the plate tune for minimum plate current.
Tech833 - Posted on Tuesday, March 30, 2004 - 4:35 pm:
http://www.copperelectronics.com/cgi-bin/discus4/board-auth.cgi?file=/34/70514.html
Tune and load both tune the final plate. Tuning is what resonates the plate while load is what 'loads' it. Plate is parallel tuning and load is series tuning, how's that?
Anyway, adjust the tune control for the lowest plate current and the load for the highest output.
Tech833 - Posted on Friday, April 02, 2004 - 2:54 pm:
http://www.copperelectronics.com/cgi-bin/discus4/board-auth.cgi?file=/34/70557.html
Tuning is what brings the final amp plates into resonance. This is the most critical control on the whole thing. Tuning should always be done first and next to last.
Tune in this order-
1. Tune the 'TUNE" control for minimum plate current.
2. Tune the 'LOAD" control for maximum watts out of the amp.
3. Retune the 'TUNE' control for minimum plate current.
4. Tune the 'INPUT' control for minimum SWR to the radio driving the amp. Then, repeat as needed until no further changes occur.
The above procedure is exactly the same as dipping the plate (tuning for minimum plate current, thus resonance) and peaking the grid (tuning input for minimum SWR into the radio, thus resonating the power tube grids).
This is exactly how I tune the magawatt monsters too. It is the same for any non-cavity tube amp.
Tech833 - Posted on Friday, April 02, 2004 - 3:02 pm:
http://www.copperelectronics.com/cgi-bin/discus4/board-auth.cgi?file=/34/70514.html
Even though you may not want to leave a watt meter inline during normal operation, you STILL need to measure the output with a watt meter. You may remove the watt meter after tuning is complete if you wish.
Tune without audio. Carrier only. If you tune with high envelope audio, you are likely tuning to harmonics and splatter too
Tech833 - Posted on Tuesday, April 06, 2004 - 11:55 am:
http://www.copperelectronics.com/cgi-bin/discus4/board-auth.cgi?file=/34/70557.html
Plate current is measured by placing an amp meter in series with the plate DC supply.
Can someone who is familiar with that amp help with this one? What is that meter reading?
You can experiment and see if that meter dips when output power increases. That might indicate a plate current sample. If not, you can substitute an amp meter on the AC supply line. Not quite as good, but better than nothing.
What you are trying to do is increase efficiency so that power is converted into RF and not heat. Heat will ruin your tubes and hurt your output power at the same time.
Tech833 - Posted on Friday, September 16, 2005 - 11:16 pm:
http://www.copperelectronics.com/cgi-bin/discus4/board-auth.cgi?file=/34/83210.html
A tube amp is almost immune to SWR. Assuming the load is not overly capacitive, a tube amplifier (with tuning and loading controls) will likely be able to be closely matched to the load with ease.
That is not to say it is O.K. to run that way, but no harm will come to the amp- IF (big IF) you tune it properly! Tune the plate tuning control for minimum plate current, NOT maximum watts! |
Caledonia
Junior Member
Username: Caledonia
Post Number: 21
Registered: 8-2005
| | Posted on Sunday, November 12, 2006 - 1:16 pm: |
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None of the tube amps Copper sells have meters for plate current, making those directions superfluous and irrelevant. With the KLV tube bases, all you have to work with is a wattmeter!
Also, none of those directions explain how to overcouple for AM, an essential step if you are using AM. |
N5xes
New member
Username: N5xes
Post Number: 4
Registered: 3-2007
| | Posted on Saturday, March 10, 2007 - 10:34 am: |
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max the grids and dip the plates. us old timers been doin' it for years. if was meant to be done any other way, then the laws of physics would have dictated otherwise I guess. been running an old 12 tube phantom 500 for over 30 yrs. on the original tubes. still clean sounding in all modes and has only dropped 40 watts in all that time. changed the original caps out for asingle , physically and electrically larger cap. and improved the overall performance and reliability by about 30%. no hum, no distortion and no dimming of the lights when i key up, and best of all, no whinny neighbors.. any way, a lot to be said about us old techs. and our antique methods that still work!!! |
