CBRT has been

Tube type tuning question

This forum is dedicated to discussions about tube radios and tube amplifiers.
Post Reply
User avatar
REDDOG45
6 PILL USER
6 PILL USER
Posts: 89
Joined: Jun 17 2011, 12:24
Contact:

Tube type tuning question

#327494

Post by REDDOG45 »

I have burned up 2 Antron 99 antennas so far from tuning my D&A phantom. Yes I know....sounds stupid. My kids do some adjusting for me sometimes when I'm at work, so I have to tune up often. The SWR sky rocketed both times at the point of tuning for max swing, then that was the end of the antenna. I have been lucky so far not to "blow any bulbs". I am trying a new tuning method which is tuning for max dead key first, then whatever that is (usually 450-500), advance the final load until that is cut in half. No more heeeeeeeloing or aaaaaaaaadio into the mic. Seems to work out just right giving me the max swing of about 800 watts which is what this amp has done the whole time. This way there is no screaming into the mic holding the high peak, and toasting these ground planes. It might just be me, but I do not understand why an Antron will not hold 800-900 watts for just 2-3 seconds.
My rig:
RCI-2950
D&A Phantom
Dosy PM2001
D104
Antron 99 @ 35'
User avatar
Nagant
Wordwide & Qualified
Wordwide & Qualified
Posts: 1,338
Joined: Dec 31 2009, 04:15
Real Name: Paul
Antenna: M104C, V-Quad
Radio: To Many To List
Contact:

#327513

Post by Nagant »

I honestly don't understand how you can be burning up Antrons with just a Phantom 500. I've seen them hit with a lot more than a Phantom could ever dream of producing and couldn't believe their ability to survive it. I ran a Phantom 500 with good tubes on an Antron for many years back in the 1990's without issue and all was still working when taken down.

Loading for max carrier is usually harder on those sweep tubes than tuning for max peak. Now if your super slow at tuning for maximum peak then it might not be much of a difference. Regardless the sad truth is tuning so often is really hard on the sweep tubes used in those amp. I understand how kids turn things and there really isn't a lot a person can do about that. Maybe think about using marks with non-permanent marker, tape....... to give you some sets lines for each control. Less tuning since the set marks will get you close.
User avatar
De_Wildfire
Donor
Donor
Posts: 929
Joined: Jun 14 2009, 19:46
Handle: De_Wildfire
Real Name: Greg
Antenna: Imax 2000. Hex Beam, G5RV dipole, Jpole(UHF/VHF) Austin Suburban Tri Band (UHF/VHF)
Radio: Washington, Tram D201, Tram D64, Robyn 520D, Cobra 139XLR, Elecraft K3S, Kenwood 590S, Yaesu FTM 400DR, Alinco DR-235, ADI-146
Contact:

#332297

Post by De_Wildfire »

I use a 50 word per minute cw "dit" tone when I tune the amp. I watch the external meter for 1.1 swr and maxium power out peak average. The external meter does everything I need and don't have to touch it while tuning.I also notice the amp meters look good too. Once you get the thing tuned, I would put markers on your amp with your tuning spots so the next time you tune, you tune, you can, "tweak it a hair." Sometimes it will behave a little different from time to time but the main thing is you get the tuning spots in the ballpark so you don't have to have long tuning periods and stress the tubes.
User avatar
Cool Mule

#351398

Post by Cool Mule »

Tuning is the hardest thing you can do to a set of finals, you know that. I try to hold it down to less than 5 seconds at a time. My old Swan 500 kicks around 490 just out of the radio. I never bother with an amp. Never ran an Antron but it should yawn at 800. Are you sure you haven't had a lightning strike that has damaged the dielectric in your feed line? You got some serious arcing somewhere. I know taking that down and sweeping it ain't no fun, but buying antennas isn't either. LOL, you may have to consider hocking the little woman's diamond ring and getting you a nice piece of hardline :)
Post Reply