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Johnson Viking II Hi Fi Audio mod
http://diyaudioprojects.com/Forum/viewtopic.php?f=16&t=6684
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Author:  Alpha Wolf [ 29 Dec 2019, 09:47 ]
Post subject:  Johnson Viking II Hi Fi Audio mod

To improve you transmit audio on your Viking 2. Replace the inner stage modulation transformer with a Hammond 124B. The stock transformer does not have enough band with. Replace all capicatiors. Change all coupling capacitors to .02 600 volt. Change the bypass cathode cap on the first 6au6 to 50mfd 50v. Change the driver 6au6 to a 6c4. For a cathode resistor for the 6c4 use 1.5k 1watt and 220mg 50 volt cathode cap.Also add a 220.mfd 450 volt cap from R3, 470k R32 1meg and R5 to ground. This gives better voltage stability to audio preamp also reduces noise. This is far better than stock audio T driver 6au6 does not have to be replaced but if used change cathode bypass cap to 50mfd 50v. That is if you want to keep stock tube lineup. The 6c4 does work better. I have had good reports on air about my audio. Got to love these boat anchors.

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