EF Johnson Viking 500 - RT's Radio Home Page

The E.F. Johnson Viking 500 transmitter was produced during the late 1950s through about 1964; it runs both AM and CW modes. This is a photo taken shortly after bringing it home. Sources indicate production of the Viking 500 was limited to 865 units, so it is fairly rare. The transmitter employs an Eimac 4–400A tetrode tube in the RF final; modulation is provided by a pair of RCA 811A's.

In 2022, I decided to get a plate-modulated AM station up and running again. A couple of long-suffering Viking Rangers came home first. In January, 2023, I found the Viking 500 above on Craigslist. I quickly contacted the owner and met with him. He had other rigs to sell, so a few more boatanchor rigs came home as well.

The underside of the power supply as found.

This is the completed power supply, underside of the chassis.

The major change/mod is the use of radial lead capacitors for the high voltage instead of those with axial leads.

The rationale for not using axial lead capacitors:

1: They are very expensive at $30+ each.

2: The radial lead capacitors installed are around $4.00 each and have better ratings, including longevity.

The new capacitors are lightly clamped into place by a square-sectioned plexiglass rod; radiused notches were cut in to cradle the capacitors. The notches are felt-lined, and there is a strip of felt under the capacitors. The leads are sleeved with insulation from 5KV test lead wire. The assembly is held in place by three longer screws with standoffs to limit clamping pressure.

The other mod is the delay circuit for relay RY302 which sequences the release of that relay to prevent arcing. No arcs have occured. (Thank you WQ9E!)

The front panel appeared to have light rust coming through the paint. I used automotive polishing compound and worked carefully to avoid the graphics as much as possible. A light coat of automotive paste wax finished it off. The brownish rust is gone.

Here is a before and after of the VFO cover. Here it has some imperfections in the paint. I do not know what these are; however, I used the polishing compound on it as well. Before (Above):

Here is the VFO cover after polishing.

I had paint mixed to match the E.F. Johnson Maroon. The 500 Case needed repainting as do all of my Johnson Viking gear. Here it is just after painting. The front rim of the Johnson Viking case is intentionally left unpainted to make electrical contact with the front panel. This is necessary to assure a good, RF tight enclosure. This case is masked off at that location.

I brought the Viking 500 home in January, 2023. Here it is May 16, 2023, and the power supply top and bottom covers are finally back on.

Here is the finished Viking 500 in the shack.

The Viking 500 Power Supply. The power supply alone weighs in at about 120 Lbs. This is the main reason it is on a cart under the desk, on the floor.

The 811A's glowing in the background assist the other tubes in this transmitter in heating the shack in the wintertime.