Special R-390A PTO Manufacturers
Some of the more rare but very desireable PTOs *
And last but not least...
Some models of the R-390A manufactured with the above PTOs have an additional control on the front panel. It is believed to be a tone control. The more the control is pulled, the more mellow the sound. The nomenclature tag was relocated for this control.
Here is a close-up view of the 807 level meter
* It has been rummered that these rare radios had an 807 hidden somewhere inside.
(Yes - these were all different receivers placed in the exact same location. Really...)