The original National HRO Senior receiver of the 1930s was a design collaboration between James Millen on the east coast and Herbert Hoover Jr. on the west coast.  It was the preferred receiver used by the British in WWII for code breaking activities due to its exceptional signal to noise ratio and a dial resetting accuracy unexcelled at the time.  This was achieved by an innovative eccentric gear dial arrangement which is a marvel of mechanical elegance.  The electrical design was equally elegant with a separate power supply, removable coils, two stages of RF amplification and numerous other refinements to minimize noise.

Collectors of National radios have written about National's 1946 run of HRO-6 receivers but, other than a scant mention and a lot of speculation, few, if any, have been found. Until now.

Below are high resolution color pictures of the only copy of a National  HRO-6T receiver we know to exist.  Historians appear to agree that a few HRO-6  receivers were manufactured in 1946, just after the HRO5-TA1 series receiver and just before the very new and radically changed HRO-7 series. However, there is no research or historical citation of how many were produced nor what the serial number series might have been.  Put another way, until now, there has been very little hard evidence of the existence of an HRO-6 series. This does not mean no others exist, there could be a few somewhere, still be be discovered.

Why is this important?  The HRO-6T is the last of the famous HRO "black box" series.  It is the end of  the classic line of National receivers going back to the 1930's. As mentioned, the HRO-7 was a radical departure.  It is very different from its predecessors, having a molded front panel, a voltage regulator, a tone control, rounded corners, gray paint, and a "hidden" S-Meter.  In short, a very different receiver, no longer resembling the classic crinkle black HRO line. Put another way, the HRO-6 series is the last line of the very receiver that made National receivers famous. Finally, being one of very few HRO-6 receivers, this HRO-6T is the rarest of the rare!  It is far rarer than the Hallicrafters SX-88.  It is historically significant as a key link in the evolution of what is arguably the most successful tube radio receiver series ever.  From the early HRO Seniors through to the HRO-6, one can see a clear lineage based on key design principles:  very low noise, high sensitivity and mechanical elegance.

Several citations indicate the HRO-6T was almost identical to the HRO-5AT1 with relatively minor circuit changes. Our comparisons of the two models verify this to be true.

Pictured below is our HRO-6T. 

Please note that ALL of the pictures that follow are
Copyrighted by K4ICL.com and may not be borrowed,
downloaded, or copied for any reason without permission.