HRO Receeivers - A Brief History

Radio collector Tom Brent presents this brief history on the HRO receiver produced by the National Radio Company.

"When National introduced their new receiver to the public in 1934 it was simply known as the “HRO”. After its introduction, James Millen became aware that hams (who mainly operated CW.) weren't using features such as the S meter and crystal filter. He therefore concluded there was a market for a cost reduced HRO with less features. Thus, the “HRO Junior” was marketed in 1936. By default, the previously introduced HRO (with S meter and crystal filter) now became known as the “HRO Senior”. The Junior was not a big seller, at least in relation to the Senior of which thousands were sold to military, government, commercial and amateur radio users. Although advertised as the  HRO Senior for a few years, it became known as simply the “HRO”, the “standard” receiver in the HRO line. Even today, when referring to HRO’s prior to introduction of the HRO-M and HRO-5, it is simply called “HRO”, a differentiation only being made if it is an HRO Junior (which are uncommon).

Radio collector Fred Archibald expands on this from information found in an AWA article on the HRO. "The HRO receiver was introduced in 1934 and sold for $170-$200. It was, a lot of money then.  Jim Millen talked to many hams and believed that there was a market for a cheaper HRO, so in 1936 they omitted the S-meter, crystal filter, and bandspread positions in the coil sets to create the "HRO Junior" which was advertised for $99. After the HRO Junior was officially introduced National began calling their HROs with S-meter, crystal filter and bandspread coils the "Standard". In other words the HRO of 1934-35 is the same as the Standard HRO of 1936 and later (except for minor production changes)"

The circa 1944 photo that was obtained from Vancouver Maritime Museum no doubt shows the HRO  receiver mentioned in Bill Morrison’s report as being acquired in 1938. The lack of a front panel ID plate dates it to no later than 1938 production. However, I question the frequency coverage he cites as 1.7 to - 30 MHz. That would only require four  sets of HRO coils). St Roch had transmitters that operated in the LF/MF marine bands and would also need a companion receiver covering those frequencies . There are currently six sets of coils in the radio shack aboard the St Roch.

The HRO currently on St Roch has obviously had the front panel ID plate removed (the screw or rivet holes are still there). It also has a chrome half-moon plate above the B+ switch and probably another one above the AGC switch (out of view in the Dean Hadley photo). I have only seen this feature on two ex-RCAF HRO’s. Henry Rogers who has amassed a huge amount of HRO information online tells me he has never seen this feature. There are two possible reasons why St Roch’s restorers would have removed the front panel ID plate: first, to make it look like the HRO in the ca. 1944 photo and second, National did at least one production run which bore ID plates with RCAF identification and serial numbers on them, something that would have been out of place."


1) Tom Brent <navyradiocom(at)>
2) Fred Archibald [hfarchibald(at)]

ck to St. Roch

Dec 22/19