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RADIOHF - Safety Warning - Very Serious I had a scary incident a few minutes ago. I was connecting a dummy load to a Johnson Pacemaker transmitter and got a whammy of a shock between the metal bench and the dummy load case. After I recovered my composure, I measured the voltage seen on the center conductor of the SO-239 connector and measured 730 volts! Having heard of their being a POSSIBILITY of a shorted plate blocking capacitor in these old radios, I held everything with a light grip. However, I did assume, as I am sure most of us assume, that Johnson had, like everybody else, placed an RF choke to ground at the output of the power amplifier. That choke is supposed to have a current rating sufficient to pull any stray high voltage to ground should that blocking capacitor fail, and blow the line fuse. Well, EF Johnson chose to not put this safety part into the Pacemaker and, I assume, every other transmitter they made in this era. I just checked the Valiant schematic and it also lacks this crucial safety part. Take Care! Listing #1750771 by W0DVN Submitted on 11/25/25 Submitted from c-75-73-126-143.hsd1.mn.comcast.net Click to Contact Back to Previous Page

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