[Milsurplus] HRO

[Ray Fantini]

For when it was produced around 1935 and up to 1940 the HRO family of receivers was possibly the best receiver produced. With modern tubes or additional stages better receivers came along during WW2 but as far as prewar goes the HRO is King of them all.
The RCA AR-60 and the over built RAK and RAL were good radios but in comparison to the HRO the RAK and RAL were larger, heavier and lacked the coverage of the HRO
The HRO did not lend itself to communications work in a heavy lift role like a RAK or RAL with a dedicated line output and stability to the point that the receiver can be set to a frequency and forget it but for intel work where you needed the ability to cover a large range of frequencies and would be scanning around the band it’s a hard radio to beat. The same features that put it as the king of the receivers in the Ham community for two decades. Think of the HRO as something similar to the Watkins Johnson intercept receivers of the sixties and seventies. Not the best receiver for all jobs but in its intelligence gathering roll ahead of the rest.
My favorite receiver is still my 1941 HRO RAS with its cryptic mechanical display and week image suppression with the military IF of 175 Kc. For a receiver that’s just turned seventy seven it still has a low noise figure and high sensitivity that exceeds most radios until you get into the solid state designs of the early sixties. Image rejection and selectivity are another story but radios like the HRO-M and MX that were heavily used in intelligence gathering had higher IF frequencies and IF filtering beyond the basic LC filtering in the RAS, At least that’s how I see it.
Its personal opinion, and people who don’t like my statements on opinion should stop reading here but I feel that there was a short period of time between the mid to late thirties possibly right up to WW2 itself where RCA and other communications equipment manufactures produced some of the finest crafted vacuum tube radios ever built.
It was almost as if for a short period of time the companies were looking at how to build a quality product without the pressure of value engineering that became a mantra in manufacturing before the end of the war and a way of life forever after.
Look at the quality of the workmanship on prewar radios or design and how that changed during the war. Radios like the early BC-348 versus the later radios like the BC-348Q, N and J where you can see the switch to point to point construction that is similar to what manufactures were doing on the consumer lines. The odd thing about it is that the HRO was built along consumer or commercial point to point technique as opposed to the military grade construction of many of its peers.

Ray F/KA3EKH

From: milsurplus-bounces at mailman.qth.net [mailto:milsurplus-bounces at mailman.qth.net] On Behalf Of Tom Brent
Sent: Wednesday, May 09, 2018 12:25 AM
To: milsurplus at mailman.qth.net
Subject: [Milsurplus] HRO

This past weekend I acquired another National HRO receiver (factory painted RCAF blue) and that prompted me to remember a question I have been meaning to ask this learned group for quite some time.

It is common knowledge that the HRO series was ordered in large quantities for intelligence monitoring purposes and in recent years I have come across a number of online and written sources that refer to it as "the premier signals intercept receiver available during World War II".  Was this truly the case or had it simply gained a reputation in the mid to late 1930's that stayed with it even though better receivers came along before and during the war?
This is not an effort to slam the HRO but rather an attempt to gain a more accurate understanding of its place in military communications history.

Your thoughts would be appreciated!
Tom
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