New TL-922 Owner

Discussion in 'Amateur Radio Amplifiers' started by G3YRO, Dec 14, 2016.

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  1. K9AXN

    K9AXN Premium Subscriber QRZ Page

    Sam,

    Have an opinion regarding only one change. There are several maladies that AMP and many others have; band switch arcing, abnormal oscillations, tube flash over, and grid component damage from arced tubes. The QSK change fixes those problems. It has been statistically proven to relieve those symptoms. For years these failures have been blamed on the grid circuit design when hot switching was the cause. The design of the grid circuit provided a measure of negative feed back to improve IMD numbers and stability.

    Enjoy the Amp

    Regards Jim
     
  2. K4ATR

    K4ATR Premium Subscriber QRZ Page

    I always used a small appliance bulb a circuit that uses a photo cell that will close a relay.
    what happens is when power is applied the bulb burns bright then as caps charge up light dims closes relay
     
  3. WE6C

    WE6C Ham Member QRZ Page

    Bryan, You're right, $400 is a lot of pennies however the parts/materials are quality and if you look at it closely, it's worth every penny. It works flawlessly.
     
  4. W1QJ

    W1QJ Ham Member QRZ Page

    Some of these may be good and some just awful. I replaced a 10 ohm 10 watt unit in an Al-1200 amplifier. I bought a two pack. Both of them instantly opened up when the step start rely engaged. I thought there was a major current being drawn and the resistor was acting like a fuse. BTW..they do act as fuses in an SB-220 using the H*rbach SS kit which uses the sand units. Once I used a good vitrous enamel resistor all was good and it never let go. SO you have to be conscience of what you use foe step start resistors. In my mind they should not blow open before a fuse of circuit breaker.
     
  5. WA7PRC

    WA7PRC Ham Member QRZ Page

    I did. IMO, it's not.
    Mine does, too, at less than half the cost.
     
  6. G3YRO

    G3YRO Ham Member QRZ Page

    I agree, that kit simply isn't worth it. (That would be half the cost of what I paid for the Amplifier!)

    As usual before buying a new piece of equipment, I talk to several owners . . . none of them ever had ANY problems with their TL-922 amplifiers.

    Roger G3YRO
     
  7. W1QJ

    W1QJ Ham Member QRZ Page

    There have been many over the years that have written volumes of papers and Internet blogs claiming all sorts of problems with early 3-500 based amplifiers. Everything from parasitics (which get the biggest blame) stability, and inferior band switches and a host of other assumptions. Several have capitalized on the fact that those who read all these assumptions believe what they read as gospel and then gladly open up their wallets for a whole host of fixes. Over the 50 years as a ham and many of those working on vintage 3-500 amps, I have seen just about every cockamamie "mod" or whatever you want to call it done to these amps. In particular, the SB-220 and TL-922. I'll agree however that these amps do get arcing at various points in the amp. I have seen arcing damage in many of the copies of each amp and some not at all. If you are after the cure for arcing you don't have to do a $400 overhaul on any amp. All one needs to do is to understand why arcing occurs. When you make 3-12 changes to an amp and then it stops arcing, what did you do to stop it? Do you know? Even if you have one of these amps and it arcs, does it do it all the time? Does it do it occasionally or better yet should I say intermittently? If the answer is yes to the latter, then why not all the time? Arcing is a "series" of events that take place. Remember the word "series" I'll come back to it. In the series of events most issues that contribute must be met. If at the time none or most that contribute do not happen the arc will most likely not occur. I call arcing in an amplifier "the perfect storm". When the issues add up the amp may indeed arc. This is why it does not happen ALL the time. The word "series" is key here. Usually is a series circuit if you open the circuit anywhere in the series, no current will flow in the entire circuit. If you eliminate one component the circuit will still flow current if a connection is made across it. But how about if you do not eliminate any component at all and do not break the circuit? How do you stop the current flow? You have to eliminate the source voltage that allows the current to flow. The point here is "eliminating the source". If you can eliminate the source of the series circuit that is the single most important fix you can make that will most likely eliminate arcing for good. Many fixes include trying to eliminate OTHER events in the chain (series) of events that contribute. That is NOT the way to go about it. Eliminating one major issue only could stop it all together! Attack one problem and that's it. This should work in most all cases providing certain things in an amp have not already been compromised. Assuming all else is good doing one simple thing should end it. So what is the one single thing? the answer is TIMING. You have to make sure that when your amp switches from RX to TX that the timing of all the switching is in the correct order. So what is that correct order? That depends on how much is being switched before transmitting. But we are interested in what part of the switching will eliminate arcing. So the simple answer is you have to be absolutely sure that the tube or tubes in the amplifier are not biased on too soon. All switching should be completed before the tubes are biased on. Open frame relays in vintage amps, and some newer ones that control bias as well as antenna switching are typically 3PDT relays. You can bet that when those amps arc and the series of events are just right that the bias armature on that 3PDT relay has completed its contact before the antenna was connected to the tank circuit!! Adding a sophisticated QSK circuit with proper timing will in most cases completely eliminate arcing if the amp is not compromised in other ways from previous arcing. Is there a simple and less expensive way? Yeah. It may not be quite as good but it works 99% of the time. Just read this, especially look at the diagram at the bottom. https://www.w8ji.com/relay.htm
     
    K4ATR and K9AXN like this.
  8. W1QJ

    W1QJ Ham Member QRZ Page

    Hmmmmm.......If I didn't care about the content I would not have spent the time writing it. It's OK if you didn't read it.
     
    Last edited: Oct 5, 2017
    K9ASE and WA7PRC like this.
  9. WE6C

    WE6C Ham Member QRZ Page

    Lou, Good write up.
    As far as the Kessler kit goes, I chose it because I like the quality of the parts and workmanship of the circuit boards etc. Personally I'm willing to pay a little more for quality since usually it pays off in the long run.

    One thing in Kessler's instruction manual that I don't think you see too often if at all is, start this mod with a perfectly good working amplifier. In other words, don't do this for a "fix", do it for an upgrade. Repair as needed first!

    I started with a perfectly good working amp. It has not been "repaired" it's been upgraded. Love the QSK BTW!

    Bob
     
  10. WA7PRC

    WA7PRC Ham Member QRZ Page

    The W7RY stuff is also top quality. It just costs MUCH less.
     

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