In article ,
Richard Knoppow wrote:

James Millen was one of the founders of National but
eventually was pushed out of the company. He started his own
company, also in Malden Mass, and probably made many parts
for National as well as his own stuff. Millen made very high
quality components.

Millen Mfg., at least at the time I worked there, was in direct
competition with National Co. on several products, and neither
company supplied the other.

The National HRO was a revolutionary receiver in its day
and stayed one of the favorites for both ham and commercial
use for some thirty years. The mechanical design is
attributed mostly to James Millen and the electronic design
mostly to Herbert Hoover Jr., son of the president of the
US.

While the HRO was a legendary product, I'd hardly call it
"revolutionary." It was a follow-on to the AGS line, with objectives
to maintain AGS performance at lower cost-to-manufacture, and to
normalize the coil-set interface so that the tuning coils could be
built all-in-one-box and interchangeable. An examination of the
schematic will show it to be essentially a copy of higher-end home
entertainment circuits of the era, with a crystal filter and bfo
added. Much of the actual performance came from use of better coils
(house-built) in the RF and IF stages, a house-built tuning capacitor,
and the house-built tuning dial was superior to almost anything else
around. In short, a relatively straightforward tried-and-proven
electrical design, but extremely well-executed in component quality
and mechanical structure, pretty much hallmarks of Jim Millen's team.

Worth noting that the NC-100, National's follow-on product, had
similar performance, with the advantage of having internally-mounted
and switchable tuning coils.

Hank