Go Back   Worldwide DX Amateur Radio Forums - Ham - CB - HF - VHF - UHF > Amateur Radio Related > Amplifiers


Amateur Callsign Lookup
Enter Callsign:

How to tune a tube amp.

Reply
 
LinkBack (1) Thread Tools Display Modes
  #21  
Old 08-19-2008, 06:27 AM
Supporting Member
iTrader: (0)
 
Join Date: Apr 2005
Location: Oklahoma
Posts: 3,075
W5LZ is an unknown quantity at this point
Default


buckaroo50,
Don't know that amplifier so take this with some 'salt'.
If the adjustment is labeled for 'matching', then I would have to guess that it's for matching the amplifier's output impedance to the feed line/antenna. Either method, watt meter or SWR meter could get you to the same place. I think I'd use one, then check it with the other maybe. And since there can be quite a difference in the adjustment range, I think I'd do it at the lowest power output that I could. That makes sense to me anyway.

---------

Just for 'grins'.

That '400' and '500' thingy with the tube names is the plate dissipation capability of the tube. A 3-400 can dissipate 400 watts and live with it. The 3-500 can dissipate 500 watts on the plate an live with it. Any more dissipation than those means that the life of the tube is being shortened by some amount. A lot more than those numbers means that you get to buy a new tube. That deals with measured plate current and voltage, not output power. There's also a sort of 'fudge factor' built into those ratings, but don't expect much of one. That means a single 3-400 will produce something on the average of maybe 200 watts output power -reasonably-. (Modulation Power + carrier power...measured on the meters, not the output RF power meter). Difficult to do with voice modes, so not done that way very often. Much easier using CW, and it still means the same thing. Them old HeathKits were nice amplifiers in their day! They didn't do miracles though, and lots of misunderstood 'numbers' are associated with them. When compared to what's available today, they ain't so nice, sort of. Still, nothing wrong with them if operated correctly.
- 'Doc

(Do I want another one? No, thank you, three was all I can stand. And there are some very worthwhile mods for them!)
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiFurl this Post!
Reply With Quote
Worldwide Radio Forum
  #22  
Old 08-19-2008, 07:27 AM
Captain Kilowatt's Avatar
Administrator
iTrader: (0)
 
Join Date: Apr 2005
Location: Nova Scotia,Canada
Posts: 3,113
Captain Kilowatt is on a distinguished road
Default

Quote:
Originally Posted by W5LZ View Post
buckaroo50,
Don't know that amplifier so take this with some 'salt'.
If the adjustment is labeled for 'matching', then I would have to guess that it's for matching the amplifier's output impedance to the feed line/antenna.

I don't think so Doc. Matching the amp impedance to the antenna/feedline is the job of the tune and load controls. I believe the match control on the back is for tuning the INPUT of the amp to provide a low SWR to the exciter. Must have missed your morning coffee did you?
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiFurl this Post!
Reply With Quote
  #23  
Old 08-19-2008, 02:56 PM
Supporting Member
iTrader: (0)
 
Join Date: Apr 2005
Location: Oklahoma
Posts: 3,075
W5LZ is an unknown quantity at this point
Default

Well, maybe not enough coffee. Although, I did say I wasn't familiar with that amplifier, didn't know what 'other' controls/knobs it may have. I figured that being on the back, it either had to be for the input or output matching. Guess I should have figured a little harder, huh?
Oh well. Got to make the occasional mistake (being perfect isn't that easy to put up with you know). Also doing well in my other occupation, fertilizer salesman!
- 'Doc
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiFurl this Post!
Reply With Quote
  #24  
Old 08-19-2008, 03:14 PM
Junior Member
iTrader: (0)
 
Join Date: Aug 2008
Posts: 3
buckaroo50 is on a distinguished road
Default Thanks

I did the match dial on the back as suggested, first with a watt meter then the swr...

I guess I made out pretty well, I had checked some forums and feedbacks on the MaCo 200 and all said that with 100% tubes that the amp should be close to 200-250 PEP range... Not sure what kind of watts were used for the feed but I loaded mine to 140 dead key and then backed the load dial off to a 70 watt dead key (feeding it with 1.5 watts in) - it will swing to over 300 watts (checking with my Dosy Pm-2001-TS and also the meter on my antenna tuner MFJ-949B).. So I would assume that the tubes are fine... My radio swings from 1.5 to 20 watts with tons of audio... Doing some radio checks, the reports were that the amp was very clean and the audio very very loud... makes me smile thinking that I swapped a Uniden 510 CB worth about $10 for the amp... after doing some cleaning and painting the cover it now looks very presentable and I am happy with the performance and audio... I made a trip to radio shack and bought an AC fan and replace the origional noisy one - now it is a lot more quiet and the mic doesn't pick the fan noise up as I have it on a shelf under the desk where the radio sits.

Again thanks for the advise and help.
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiFurl this Post!
Reply With Quote
  #25  
Old 11-11-2008, 04:33 AM
Suicide Ride's Avatar
Junior Member
iTrader: (0)
 
Join Date: Nov 2008
Posts: 29
Suicide Ride is on a distinguished road
Default

Quote:
"makes me smile thinking that I swapped a Uniden 510 CB worth about $10 for the amp..." & "I made a trip to radio shack and bought an AC fan and replace the origional noisy one"
Nice job! I can remember when 510 Unidens were tossed in piles under the bench 'cause there wasn't any room inside for toy(s) ie; copy-cats, connex boards, etc., & a Maco 200 should have 4 ea. 8950 tubes @ $80 a piece!

BTW, w/the cost of fuel (& a LACK OF FUNDS!), whenever I need to replace a fan in a amp, I go to my "stockpile" of parts cannibilized from old microwave ovens that I've picked up on the side of the road. The fan shape is designed to move max cfm. for tube cooling w/minimal noise. Just remember to use soft rubber washers between the fan brackets & chassie mounting screws for sound isolation. Believe it or not, there's quite a bunch of good, "usable" stuff in an old microwave... fans, grounded three-prong plugs, sheetmetal screws, fuse holders, micro-switches, caps, diodes, etc... It saves time parts-running, & $$$! Just as long as you've got the room to store it all.


Quote:
"DON'T NEED NO STINK'IN ANTENNA?!! I KIN' TALK ALL 'ROUND MY NEIGHBORHOOD USE'N 3.5Kw ON MY DUMMY-LOAD!":Alligator station: All mouth - No ears!
:
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiFurl this Post!
Reply With Quote
  #26  
Old 12-31-2008, 04:05 PM
KB3OWN
iTrader: (3)
 
Join Date: Apr 2005
Location: EDGE OF THE WOODS.Maryland
Posts: 77
skipshooter205 is on a distinguished road
Default

good trade in my book a 30$ radio for a 100+$amp the 8950 tubes are hard to come by but they are out there figure this is what it has ?
__________________
KB3OWN
Icom/yaesu/kenwood/uniden
Army stick CTE-LW-150
modified wilson 5000
RCI-2950 modified wilson 1000
http://skipshooter205.proboards23.com
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiFurl this Post!
Reply With Quote
  #27  
Old 02-07-2009, 12:48 PM
Junior Member
iTrader: (0)
 
Join Date: Sep 2008
Posts: 10
Smoke is on a distinguished road
Default

Does this procedure work on a Blackcat 2000?
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiFurl this Post!
Reply With Quote
  #28  
Old 02-07-2009, 12:53 PM
Junior Member
iTrader: (0)
 
Join Date: Sep 2008
Posts: 10
Smoke is on a distinguished road
Default

Is there a repair center that will repair a Scout 20?? If so, is there one close to Indiana?
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiFurl this Post!
Reply With Quote
  #29  
Old 04-22-2009, 05:56 AM
Senior Member
iTrader: (0)
 
Join Date: May 2005
Posts: 415
Mr Clean is an unknown quantity at this point
Default

PM sent Smoke.
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiFurl this Post!
Reply With Quote
  #30  
Old 04-22-2009, 06:04 AM
Senior Member
iTrader: (0)
 
Join Date: May 2005
Posts: 415
Mr Clean is an unknown quantity at this point
Default

Quote:
Originally Posted by unit_399 View Post
QRN -

I didn't know what the ratings on the amp are. I bought it used down here without any documentation. It deadkeys about 800 watts and around 1500 modulated with the setup I described. I don't run the box very often. I get good results with my solid state amps and I really don't need that much power. The price was right, so I bought it. BTW, mine has 3-400Z tubes.

- 399
Thats alot of dk for that amp. They were built for SSB. Nomad has some nice mods to make SB220s run cooler on AM. the power supplies are alittle wimpy for AM but they are nice amps if driven right. I have the smaller SB 200. I run it at about 125 watts dk and 650 or so pep. 600 or so SSB.
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiFurl this Post!
Reply With Quote
Reply

Bookmarks


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


LinkBacks (?)
LinkBack to this Thread: http://www.worldwidedx.com/amplifiers/26225-how-tune-tube-amp.html
Posted By For Type Date Hits
Tune tube AMP This thread Refback 09-26-2009 07:43 PM 19


All times are GMT -7. The time now is 10:40 PM.


Powered by vBulletin®
Copyright ©2000 - 2009, Jelsoft Enterprises Ltd.
Search Engine Optimization by vBSEO 3.3.2
Worldwide Radio Forum