Category Archives: Boat Anchors

WWII Radio: Truman and the Scott Radio Labs RBO-2

Many thanks to SWLing Post contributor, Kim Elliott, who recently shared the photo above of President Harry S. Truman via @RealTimeWWII.

If I’m not mistaken, that is a Scott Radio Labs Model RBO-2.

I’m guessing that’s also the speaker mounted on the wall directly above the receiver.

Scott Radio Labs marine receivers were shielded to the point that they had very low local oscillator radiation. This design prevented detection of the ship via the enemy’s use of radio direction finding gear.

I have a commercial Scott Marine Radio Model SLRM–it is my favorite receiver and I use it daily.

Post readers: Anyone else have a Scott Radio Labs receiver in their shack? Please comment!

Seventy years ago, Thor Heyerdahl packed a National NC-173 and made history

The National NC-173

Many thanks to SWLing Post contributor, Kris Partridge (G8AUU), who sent the following feedback a few days ago. Sorry for missing the boat, Kris!

Kris writes:

Just under two weeks ago I was watching a Norwegian film on Polish TV (no, don’t ask) and knowing how the sight of old radio’s in films is of interest to you and your readers I was going to write but travel and work, Passendale100 commemorations in Belgium, got in the way. The radio in question was a National NC-173 receiver. And the film Kon-Tiki.

There is much written about the exploits of the voyage and the operators of LI2B. I give as an example from PA7MDJ http://pa7mdj.blogspot.co.uk/2016/10/the-kon-tiki-expedition-and-heroes-of.html?m=1 I leave it to PA7MDJ’s most excellent blog to tell more, he has some Nation Radio Company images from 1947 illustrating his piece and at the end there is a very extensive links listing.

But another reason for writing is that tomorrow, Monday, 07 August is the 70th anniversary of the end of the voyage as the raft landed on the reef. On the 67th anniversary the ARRL did an article on LI2B, why the 67th?

What happened on the 7th of August 1947, and in the 36 hours after, says much about the build quality of the National NC-173.

How many radios today would survive a dunking in seawater and after drying out still be working?

I’ve just been to my book shelves and after a small search found my copy of The Kon-Tiki Expedition published in 1950 given to me not too many years later.

You find LI2B in the book’s index twice. Once describing the operation of the radio ‘corner’ and a very QRP contact between the raft and Oslo Norway. 6 watts CW on 13990 kc. per second, the book being written in 1949 no kHz.

LI2B had been given permission to operate out of but adjacent to as well as in the 20 metre band. The second entry concerns what happen after the raft ends up on the reef and the radio shack and equipment got flooded.

They had been in contact before hitting the reef and there was a 36 hour window before the air search and rescue operations would begin. The drying out of the equipment took no little time and the writer describes how slowly the receiver came to life but no transmitter.

Finally they were able make contact, just before the 36 hrs ended,using a WW2 hand cranked resistance, the book says sabotage, transmitter.

Both the radio operators on the Kon-Tiki had been radio operators in the Norwegian resistance in WW2, only 2 years earlier.

If one puts LI2B into Google images quite an interesting assortment of radio related images are found (click here to view search), including QSL cards but the one I like best is this http://f6blk.net/photos/LI2Bshack_x1.jpg:

I’m sure I’ve seen an English language version, this one looks slightly cropped since the end of the ‘Earth’ wire is out of vision

Regards es 73 de

Kris G8AUU

How fascinating! Thanks so much for sharing this, Kris.

Again, apologies I didn’t get this posted prior to the 70th anniversary–I’m a tad behind (understatement alert) on email at the moment.

I have a particular affinity for The Kon-Tiki Expedition. I found a 1950s copy of the book while doing my undergraduate degree ages ago.

My 1950s copy of The Kon-Tiki Expedition in an archival cover.

The book played no small part in my fascination with anthropology–especially Heyerdahl’s version of “applied” anthropology. I went on to do my post grad work in anthropology at the London School of Economics. Indeed, I re-read that book before my finals to remind myself the significance of anthropology.

If you haven’t read The Kon-Tiki Expedition, I highly recommend you do so! Indeed, it’s about time I read it again.

I’m very curious how many SWLing Post readers have a National NC-173 sitting in their shack? Thor would tell you to take care of it, because it certainly took care of his crew!

Mike spots the RCA AR-88 in series “Prime Suspect: Tennison”

Many thanks to SWLing Post contributor, Mike Hansgen (K8RAT), who adds the following to our growing archive of radios in film. Mike writes:

Near the end of the current episode of “Prime Suspect: Tennison” [the radio operator mentions] he was listening on “the RCA 88”.

“Tennison” is set around the early ’70’s.

Great catch, Mike (and thanks to Eric WD8RIF for the screen cap).

According to the Crypto Museum:

The AR-88 was a valve-based shortwave general coverage communications receiver, developed and built by the Radio Corporation of America (RCA) in the early 1940s. Although the receiver was initially intended as the successor to the AR-77 amateur receiver, the outbreak of WWII made it evolve into a professional high-end military-grade receiver for which cost was no object.

The AR-88 is a 14-valve (tube) receiver, which covers a frequency range of 535 kHz to 32 MHz. Unlike the National HRO receiver, which had pluggable coil packs for each frequency band, the AR-88 uses a six-position band selector. A special version of the receiver, the AR-88LF, was suitable for LF and MF, covering 70 to 550 kHz (continuously) and 1.5 to 30 MHz (continuously).

Continue reading at the Crypto Museum online… 

The Crypto Museum photo of the AR-88 jogged my memory…

Last year, I visited the Musée de la Défense Aérienne at the Canadian Forces Base (CFB) Bagotville (a museum I wholeheartedly recommend, by the way).

I snapped this shot of this display:

I’m sure I actually have a close up of this receiver somewhere. It also appears to be an RCA AR-88 based on dial and control configuration, though I certainly could be wrong.

Do any SWLing Post readers have an AR-88? Please comment!

Photos of a B-17G Radio Operator Position

I had the pleasure of visiting the Champaign Aviation Museum recently and examining their under-restoration B-17G, “Champaign Lady”. Actually, the term “under-restoration” is incorrect. In actuality, the Champaign Aviation Museum is effectively building their B-17G nearly from scratch—quite an undertaking but one that the volunteers are performing skillfully and enthusiastically.

Being an amateur radio operator, shortwave listener, and would-be WWII-radio restorer, I was was pleased to see that Champaign Lady already has a nearly-complete radio-operator position installed, between the bomb-bay and the waist-gun section of the airplane. As a B-17G would have had during the war, Champaign Lady features a BC-348 liaison receiver and morse-code key mounted on a desk on the port (left) side of the bomber and a stack of AM/CW Command Set transmitters and receivers racked on the starboard (right) side of the bomber. In the photos, the top Command Set boxes are the transmitters and the bottom three Command Set boxes are the receivers. Of course, the BC-348 and the Command Set transmitters and receivers are fully tube-type, semiconductors having not yet been invented. During the war speedometer-type cables would connect the Command Set receivers to controls in the cockpit, allowing the pilot and co-pilot to control the Command Set receiver frequencies; electrical cables would have carried the receivers’ audio to the pilot and co-pilot and would have allowed them to change volume-level. The radio operator could transmit using the Command Set transmitters and could also switch the pilot or co-pilot intercom microphones to any of the Command Set transmitters to allow the pilot or co-pilot to broadcast to other bombers in the formation.

"Champaign Lady" radio operator position

B-17G “Champaign Lady” radio operator position; BC-348 liaison receiver on the port (left) side and Command Set transmitters and receivers on the starboard (right) side.

"Champaign Lady" BC-348 receiver

B-17G “Champaign Lady” BC-348 liaison receiver and morse-code key.

"Champaign Lady" Command Set transmitters and receivers

B-17G “Champaign Lady” Command Set transmitters and receivers on the starboard side of the radio room

During the war, the B-17G radio operator was an enlisted man, typically a sergeant or higher in rank. If in an earlier version of the B-17G, the radio operator was also responsible for manning a .50 caliber machine gun located in his section of the airplane. In all versions of the B-17G, the radio operator assisted the navigator by providing position reports based on radio fixes of beacons or radio stations. Additional information about the role of the B-17G radio operator can be found on the B-17 Queen of the Sky website.

And, for those interested, here is what Champaign Lady’s nose-art looks like:

B-17G "Champaign Lady" nose-art

B-17G “Champaign Lady” nose-art, starboard side; the port side features a mirror-image version of the same design

The Champaign Aviation Museum has a beautifully restored B-25J, “Champaign Gal”, in flying condition. Unfortunately, I’ve not been able to see if Champaign Gal features a restored radio operator position.

I have a BC-224, which is the 12-volt version of the BC-348 liaison receiver to put back into service as well as a BC-696A Command Set transmitter that I hope to eventually put back onto the air in the 80-meter amateur band. It would be wonderful if I had a B-17G in which to install these items—or even just room to build a replica B-17G radio operator position!

73,

Eric McFadden, WD8RIF
http://wd8rif.com/radio.htm

Dan sheds light on various Hammarlund SP-600 models

Many thanks to SWLing Post contributor, Daniel Hawkins, who leaves the following comment in reply to our previous post about the Northern Radio SP-600 and discussion about diversity operation. Dan writes:

Diversity operation: two or more receivers and antennas used to copy CW or RTTY from one or more transmitters.

Most of the Hammarlund SP-600s were models built for diversity use including the well-known JX-17, the most common SP-600. Diversity models can be used as single receivers. In this eBay example Northern Radio has modified a SP-600 J-11 for diversity use.

SP-600 nomenclature: J means joint army/navy (JAN) mil-spec components. L means low frequency. X means crystal frequency control in addition to VFO. My SP-600 is a JX-21, which is not a diversity model. Higher model numbers do not necessarily mean later production dates. All SP-600s use the same serial number sequence regardless of model. Somewhere between serial numbers 15,000 and 17,000 (mid 1950’s) Hammarlund stopped using molded black beauty capacitors and switched to installing ceramic capacitors.

The two-digit model numbers indicate model types. JX-1, 7, 10 and 21 were similar non-diversity receivers. SP-600s built for military contracts will have an additional tag showing the military model number(s).

Here is a great page showing Northern Radio modified SP-600s in action with accompanying Northern Radio RTTY gear.

http://www.navy-radio.com/rcvrs/frr28.htm

Thanks for the primer, Dan! I believe I have one of the X models with crystal control, but I’ll need to verify once back home. Any other SP-600 owners out there in the Post readership?