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Author Topic: VIKING2..POWER GOOD,PLATE CURRENT LOW..160  (Read 3599 times)
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ve6pg
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« on: February 28, 2006, 02:49:58 PM »

HI FROM TIM,AGAIN...FIXED UP THE VIKING WITH C10/11...LOTS OF GRID DRIVE..BUT NOW,I GET 100 WATTS ON 160,BUT LOW PLATE CURRENT...ABT 100-150 MILS...OUTPUT SAYS 110 WATTS ON DIFFERNT WATT METERS....PLATE CURRENT IS HIGHER ON ALL OTHER BANDS,AND SAME OUTPOOT...WHAT GIVES HERE..?...SK..
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...Yes, my name is Tim Smith...sk..
KR4WI
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« Reply #1 on: February 28, 2006, 04:12:47 PM »

Hello Tim:;   The Manual say's  The final tuning on 160 will be very broad.  And if you are using a high impedance ant the final may be against the stop "0" end when resonance is indicated. In this case leave the main dial at "0"  and advance the "coupling" toward higher numbers. Do not advance "coupling" beyond 6 and "fine coupling" past 50 in any case. a further reduction in output capacity indictes that the antenna terminal inpedance is out ot the range of the tx. although you may feel the tank is out of resonance, the circuit is so broad that good resonance conditions still exist and its efficiency is not impaired.   

I dont know if this helps you any, but its all I found on tuning on the 160 mtr band. maybe someone else will chime in and help you with it, I have only had my viking ll for couple weeks now, and dont know much about it.  Matthew
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WQ9E
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« Reply #2 on: February 28, 2006, 05:42:52 PM »

Hi Tim,

The first thing I would check is the meter shunt for the final current in your Viking 2.  Johnson used small pieces of resistance wire cut for the needed shunt value and placed in the circuit and often the value is way off on these.  I, among others, spent a fair amount of time chasing low output on a piece of Johnson gear only to discover that the shunt resistor was of the wrong value and the plate meter was not reading correctly.  In my case, the shunt value was high causing the meter to read more current than actual but if the shunt was cut short in yours then the plate meter is reading below the true value.  I don't have my manual handy but as I recall the value for the shunt is less than 1 ohm so you will need a lab grade meter or wheatstone bridge to measure what is in there.  Instead, you could insert a known accurate VOM set to measure current in series with the HV feed TO the RF choke that feeds the final.  Be very careful if you do this since the meter will be raised up to the HV level.  Many DVM's won't like this nor will they like the RF environment so you are better off using a classic Simpson 260 or something similar.  You could also put a known accurate low value resistor in series with the HV feed and measure the voltage drop accross the resistor and use Ohm's law to calculate the current.   You could also simply replace the nichrome wire shunt with the correct value using modern precision resistors, perhaps in parallel to get the value you need.  Mouser (www.mouser.com) is a good source for low value, precision resistors-this is where I got mine to replace the ones in my Valiant.

You may have another issue since you apparently have a difference on 160 versus the other bands but before spending a lot of time troubleshooting I would check the accuracy of the built in meter.

73, Rodger WQ9E
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Rodger WQ9E
ve6pg
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« Reply #3 on: March 05, 2006, 11:29:44 AM »

...WITH THE HELP OF BOB,'ZM,I GOT THINGS WERKING OK FINE....MESSED UP C10/11,MOST RESISTORS WAY OUTTA WACK,AFTER ALL IS SAID ES DONE,LOTS OF GRID DRIVE,POWER OUTPOOT IS GOOD,160-10 BEHAVING AS THEY SHUD..TNX TO ALL WHO RESPONDED....TIM....SK..
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...Yes, my name is Tim Smith...sk..
W3SLK
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« Reply #4 on: March 05, 2006, 01:13:54 PM »

I heard you last night on 160 Tim. The Viking II sounded pretty stout.
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Mike(y)/W3SLK
Invisible airwaves crackle with life, bright antenna bristle with the energy. Emotional feedback, on timeless wavelength, bearing a gift beyond lights, almost free.... Spirit of Radio/Rush
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