Kenwood TS-830 Survival Manual

Also see for TS-830: Instruction manual

Contents

177.5 Slow power drop-offQuestion: I've been tuning my 830S through a good 50 Ohm dummy in the tune mode and pre-tuning the antenna tuner in this mode also so I would not damage the finals. The last two days Ihave noticed that after warmup, tune and pre-tune of the tuner the power will slowly drop offrom 110 W to nearly 50 W. Another interesting thing, during the tune-up stage, as I max thedrive I noted it would max.. then slowly increase at about 1/4 more than the max. I would thencontinue with dipping the plate etc. with 100 to 110 W out. If I held the key on tune or CW Iwould peak at 100 then the power would slowly drop to 50 W over 10 seconds. I have not heldthe key longer than that… (Glen KD5NVC)7.5.1 Slow power drop-off: Answer 1The 830S is now officially an "old" rig, since it was on the market in 1980, some 21 years ago.If it has the original tubes, it's very likely they're very worn out! Even if it's on its second orthird set of tubes, this is quite likely, especially if the tuning process is ever prolonged.There's no reason to spend a lot of time tuning up a TS830S. Adjust the external antenna tuner,if you must use one, with the 830S running very low power in the CW or RTTY mode, wherethe power can be turned down to almost nothing. Once the tuner is all adjusted for the bestpossible match, run the drive back up and spend the next five seconds optimizing the PA tuning.If it takes longer than that, you're really doing something wrong. There's no reason to dip theplate current, etc, that's a guideline.I used to tune my 830S "on the fly," by simply dialing up a frequency where I wanted to make acall, pressing the mike button and making the call while quickly adjusting the TUNE and LOADcontrols for maximum output on either the 830's relative output meter or an external wattmeter,using my voice as the signal. That gets it tuned fine in just a few seconds.The leading cause of 6146 and 12BY7 failure in the Kenwoods has always been "tuning up."Keep it brief, and do your adjustments at low power, then a very short touch-up of only the PATUNE and LOAD controls (no reason to go back and re-peak the driver stage, it won't change),and you're done. I'd surely change the 12BY7 and the 6146's, follow the neutralizationinstructions in the manual for re-neutralizing the 6146's, put it back together and keep tune-upsshort! They'll all last about ten years if you follow that rule. (Steve WB2WIK/6)7.5.2 Slow power drop-off: Answer 2Hi Glenn: If the plate voltage on the finals is not dropping, I would definitely suspect the finals.Most power tubes begin dying the same way - by losing emission after they have been workinga few minutes. I suspect I have changed a thousand or more of various types from 45's and6K6's up with that same problem. (Pete AC5E)7.5.3 Slow power drop-off: Answer 3My TS830 is in its 20th year with me.... a year and a half ago, I replaced the 12BY7 afterexperiencing the same symptom. Touch wood, I'm still on the original finals. Having used tubefinals in my HF rigs since I got licensed 36 years ago (yikes!), I have found the power drop-offsymptom to have always been a dying tube.By the way, I don't think you have to be overly careful about tune-up - just don't keep the keydown too long, and it can be done fairly quickly. I adjust the load for maximum output, dip theplate current, then go again with the load for maximum output in my outboard power/swr meter,and back again to dip the plate current. Each time the dip is less deep, and output powerincreases. Hey -- after all these years I still love this rig, which is as comfortable as an old