I just took the top off a 3 to 6 MHz Command Receiver (w/o nameplate) and much to my surprise 5 of the 6 tubes are glass, not metal. This is not a hack job as the top cover lists the following tube complement: 3x 12SK7GT 1x 12SR7GT 1x 12A6GT 1x VT-132 Can anyone enlighten me, please? Is it a BC-454 or some rare aardvark? -John ===============