Dating rca vacuum tubes
It is all original and has its complete original coil set (15 coils) in the original rack mounted coil holder.
In March 1933, Radio News published an article by James Millen titled "Testing a Modern Superhet" that described National's procedure for testing and aligning the AGS receiver.
Each receiver was hand tested and aligned by engineers at National resulting in a very modern receiver that provided excellent sensitivity and selectivity (along with top-notch image rejection due to its TRF amplifier stage.
Frequency coverage of the RHM is 2.3mc up to 15.0mc using a set of 15 coils.
The RIO didn't use plug-in coils but had two switched tuning ranges that covered frequencies below 500kc.
I have owned the RHM receiver shown above since 1990.
Also, National produced a long wave receiver built along the same lines as these early airways receivers, the RIO.By the early thirties, National had grown from a company that produced radio parts and regenerative TRF receivers into one of the top shortwave receiver producers in the country.National's chief engineer and general manager, James Millen, had guided the company from its early radio designs (that usually had National as a parts supplier) into the new shortwave receiver market that was becoming popular by 1930.If the ham really wanted the AGS-X he could wait for the introduction of the HRO (in early 1935) at which time Leeds was selling the AGS-X for 3.Or, if the ham couldn't wait, he could opt for the Hammarlund Comet Pro, the only other commercially-built shortwave superhet available at the time.