Category Archives: Tank Radios

#11 The Radios: The Sherman Tank Had Some Of The Most Advanced Radios In The World At The Time

The Radios: The M4 Tanks Radios Were Cutting Edge Technology For Their  Time, and Better Than German Tank Radios. UPDATED 1/4/18

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An SCR-528 Radio in turret bustle of an M4A3 76w HVSS tank.

US Army and Marine Radios

The Sherman tank came with a SCR-508, 528 or 538 radio set. Command tanks had an additional SCR 506 mounted in the right front sponson. This let the tank listen on the net for the HQ they answered to while still talking to his own unit. The main radio set also had the tank intercom built into it.  This intercom allowed the crew to talk to each other, but not transmit on the radio, only the tank commander could do that, and as we will see, in a few cases he couldn’t either.

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An SCR-528 with the canvas dust cover installed and open.

Let’s talk about the radios, now that I know a little more about them.  The SCR-508, 528, and 538 were all in the same family. The TM covering these radios was TM 11-600 Radio Sets SCR-508-A, C, D, AM, CM, DM; SCR-528-A, C, D, AM, CM, DM; and AN/VRC-5 and it was very informative on how these radios worked. These radios were all FM band radios, used because FM radios deal with interference from the tanks electrical system and motor better than AM radios. This did present a problem, in that the only radios the infantry or artillery used that could talk to the tanks were at battalion level, since they were using AM Radios at the company level and lower.

SCR-508: This radio had the most options of the three basic radios that could come in a Sherman tank.  This radio set included a BC-604 Radio Transmitter, and two BC-603 Radio Receivers mounted on an FT-237 Mounting Tray. This gave the basic Sherman with this radio the ability to transmit on 10 FM channels, and listen on up to 20, if they had the crystals for all the channels. I’ve read a few things here and there that make me think they may have restricted how many frequency crystals could be carried, but that may have been just for the infantry. The BC-604 has a drawer with room for all the crystals for its frequency range. The frequency range was (Mc) 20 to 27.9.  This radios transmitter was 25 watts and had a range of 7 miles moving, and 10 to 15 while stopped. It could be powered by 12 or 24v dynamotors. This radio came in at 181 pounds. The tanks intercom was also controlled through it, and BC-606 Interphone Control Boxes mounted at each crew station.  These radios would be found in platoon leaders, and company commanders tanks.

SCR-508_Data
SCR-508 Data Sheet

SCR-528: This radio was exactly the same thing as the 508, but with one less BC-603 Receiver. In most cases the spot where the 603 would have been was taken up by a CH-264 Parts Chest. A 508 could be turned into a 538 or the other way very easily. This radio would normally be the radio installed in the standard gun tanks of the platoon and company. This Radio came in at 181 pounds, and the same specifications other than only having the one receiver.

SCR-528_Data
SCR-528 Data Sheet

SCR-538: This radio would only be installed in tanks when there was a shortage of 508 or 528 at the factory or in a battalion itself.  This radio did have one feature that set it aside from the ones above, because it lacked a transmitter, it needed a BC-605 Interphone Amp for the crew intercom system. This one came in at only 135 pounds.

Data Sheet for SCR-538
Data Sheet for SCR-538

SCR-506: This radio would be the rarest of radios installed in Shermans. This “Command Tank” radio would only be installed in the battalion commander’s tank. On early small hatch Shermans, this radio would have taken up some ammo space in the right sponson near the BOG. In later large hatch wet tanks, they lost some .30 cal storage. It could be operated either on 12 volts or 24, and was designed for vehicle use. It would only be able to talk to Battalion level HQs and higher, and the tanks normal radio, probably in most cases a SCR-508, would be used to talk to the tanks in the battalion. This radio could have four preset frequencies, and also an adjustable range from 2-4.5(Mc) transmitting, and 2-6 (Mc) receiving. This radio was hefty and came in at 176 pounds. It was made up from the BC-652 Receiver, BC-653 Transmitter, and the FT-253 Rack Mount.

Data Sheet for the SCR-506
Data Sheet for the SCR-506

 

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US Army M1938 tanker helmet, along with an M1 steel helmet, also the intercom control box and throat mikes are seen in the left, along with the headphones in the tanker helmets ear covers. The Steel pot helmet was often worn over the Tanker Helmet.Photo Source: Mike Roof.
USWWIIM1SteelHelmets1
This image shows the Sherman tanks intercom gear adapted to the steel helmet M1. It also shows an M6 periscope and an odd microphone I’m not familiar with. Photo Source: Mike Roof.  Photo Source: Mike Roof.

Here’s a Video of an SCR-508 the has been restored in use.

Here’s a Video of an SCR-506 that has been restored in use.

. . .

Destruction of these Radios would be top-priority for the crew if they had to abandon a disabled tank. After watching videos of restored versions of all these radios, I have to say the biggest surprise is all the mechanical noise as they warm up or transmit. It was also a surprise at how clear the voice was on a 508 in good working order. After reading through the manual for the 508 it is clear, these old radios needed a lot of work to keep them operating. There is a long list of things that have to be inspected, cleaned and lubricated to keep the thing working. These radios all used tubes, and those tubes, (much like a little lightbulb, if you have no idea what one looks like), also had been removed, and inspected and cleaned. These tasks would all add to the daily grind of being a tanker and keeping the steel monster working.

Radios used in Commonwealth and Lend Lease Shermans

VC-WirelessBustle-2
a Wireless Set Number 19 in a Sherman tank.

When the British took possession of a Sherman they installed the British Wireless Set Number 19, and it replaced the intercom system as well. It was designed by the British Company Pye Ltd. It was slightly smaller than the US radios. At the level these radios were on, I doubt a British Sherman and an American Sherman could talk to each other. These Radios were made in the USA by RCA and installed in tanks slated for Lend Lease use.

These Radio sets were both more advanced, and less advanced than their US Counterpart, A true Transceiver, the first, meaning the receiver and transmitter were part of the same unit and shared circuitry. They used UHF for short range direct view tank to tank communications and HF portion could transmit up to 50 miles. These radios were not on the same frequency ranges as the US Army, and they were not as suitable to vehicle use. They were cheaper and simpler to build though and they were a powerful Transceiver.

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Another Wireless Set Number 19 in a Sherman, this one with Wire Guards.

The WS19 set had three systems. The A portion was a High Frequency radio transceiver with a range up to 50 miles. The B Portion was a Very High Frequency transceiver for short range, line of sight communications up to a mile. The final part was an audio amplifier for the crew intercom system. It had control boxes mounted at each crew station just like US tanks.

CanadianWWIITankerEquipment

Photo Source: Mike Roof.

Frequency range:

A setMkI: 2.5 – 6.25 MegaHertz (MHz), MkII & III: 2 – 8 MHz

B set – 229 – 241MHz

Modulation modes:

A set: Amplitude Modulation (AM) for speech, Continuous Wave (CW)

and Modulated Continuous Wave (MCW) for Morse code transmission.

B-set: AM speech only

Approx Power output: A-set: AM & MCW 1-3 Watts (W); CW 3-5W, B-set: 0.4W

Number of valves: 15 thermionic valves (termed tubes in the USA)

Size/weight: WS19 17.5×8.5×12.5 inches – 40lbs,Power Supply Unit 6×8.5×12.5 inches – 25lbs

Aerial Variometer 10×5 inches cylinder – 5lbs

Power Supply: 12 Volt (V) or 24V lead-acid batteries driving rotary motor-generators,

which provide 275V at 120 milliAmps (mA) for the receiver and 500V at

50mA for the transmitter.

Here’s a video of a Wireless Set Number 19 in use after restoration.

. . .

Sherman Radios in use:

 

Here is a fascinating transcript of a marine tank company’s radio chatter, taken by a US destroyer off shore during the fighting on Okinawa. You can find this on page 64 of Michael Greens M4 Sherman at War.

Troops_and_M4_Sherman_tanks_of_10th_Army_advancing_on_Okinawa

“This is Red Two, Red One; heartburn says that he is ready to start shooting at those pillboxes”

“Tell Heartburn I can’t receive him. You will have to relay. Tell him to give us a signal and well spot for him”

“Red Two wilco”

“Heartburn, raise your fire. You’re firing right into us”

“That’s not Heartburn, Red Two, That’s a high velocity gun from our left rear. I heard it whistle. Red One out.”

“Red Three, this is Red One. Can you see that gun that’s shooting into us?”

“Red One, I think that’s our own gunfire.”

“Goddamnit, it’s not, I tell you. It’s a high velocity gun and not a howitzer. Investigate or there on your left. But watch out for infantry; they’re right in there somewhere”

“Red Two, tell Heartburn down fifty, left fifty”

“Red Two wilco”

“Red Three, what are you doing? Go south west!”

“I’m heading south west Red One.”

“For Christ sake, get oriented. I can see you, Red Three. You are heading are heading northwest. Fox Love with hard left brake. Cross the road and go back up behind that house”

“But”

“I don’t know why I bother with you, Red Three. Yellow One, take charge of Red Three and get him squared away. And get that gun; it’s too close.”

“Red One from Red Two, Heartburn wants to know if we are the front lines”

“Christ yes we’re plenty front right now”

“This is Red Two, artillery on the way”

“Red one wilco”

“Red One from Yellow One. I can see some Japs setting up a machine gun about 100 yards to my right”

“Those are our troops Yellow One, don’t shoot in there”

“The man at my telephone –  I think he’s an Officer, – says we have no troops in there.”

“Yellow Two, go over there and investigate. Don’t shoot at them; that man at the telephone probably doesn’t know where the troops are. If they’re Japs, run them over.”

“Yellow One, wilco.”

“Go ahead, Yellow Two. What in God’s name are you waiting for?”

“I’m up as far as I can go and still depress my machine guns.”

“The hell with your machine guns! I told you to run over them! Run over them, Goddamnit; obey your orders!”

“Yellow Two, wilco”

“Yellow One, what have you to report on that machine gun?”

“Red One, a Jap stood up and threw a grenade at us so I gave him a squirt.”

“Did you run over that gun like I told you?”

“No. Red One, we put an HE into it and wrecked it.”

“Christ, won’t you people ever learn to conserve your ammunition…”

“Red One from Green Two, I’m stuck between two trees.”

“Green Three stand by him. After the infantry has cleared up around there, get your assistant driver out and tow him clear.”

“Green Three, wilco”

“While you’re waiting, Green three, keep an eye out on that house on your right. I see troops coming out of there with bottles in their shirts.”

“Can I send my assistant driver over to investigate?”

“Stay in your tank”

“Yellow One, from Red Three, where are you going?”

“Red One from Green Four. I am moving out to take out a pillbox the infantry pointed out I will I will take care of it and let them catch up.”

“Where is it, Green Four?”

“In that clump of bushes to my right.”

“Can you see it? It is all right to fire? Wait Green four”

“Green Four wilco”

“Green Four, you better not fire. The 4th Marines are over there somewhere.”

“Run up on the box and turn around on it”

“It’s one of those coconut log things. It looks like it my be to strong to squash. Is it all right if I fire into the slit?”

“Affirmative, but be careful, wilco”

“Red One, this is Hairless. We’ve got some Japs bottled up in two caves in Target Area Four Baker. We’d like you to leave two tanks to watch them.”

“You know damn well that’s infantry work. We’re a mobile outfit, not watchdogs. Put your saki drinkers in there.”

“Ok Harry, Red One out.”

“All tanks start ‘em up. Move out now. Guide right and form a shallow right echelon. As soon as we hit the flat ground around the airfield, spread out to one hundred and fifty yard interval. Al right, move out, move out

. . .

The fighting on Okinawa was brutal and they lost a lot of tanks. There was Army and Marine tankers there, all operating Shermans, mostly M4A3s, but a few late model M4A2s were mixed in with the Marines. I thought it was very interesting how much they talked about what they wanted to shoot, and how they had to rely on each other to confirm if a target was friendly or not.

I also thought it was amusing when Green Three asked if he could send his assistant driver to check out the log bunker. I really suspect it was sarcasm. The tankers seemed reluctant to run over Japanese out in the open. Was it because getting in that close was dangerous, or because cleaning people out of the treads after the fight was really gross? Morbid questions aside, being a tanker in the Pacific had its own share of risks, and took men with a lot of guts, and stamina.  Many of the fights took place in very warm locations, and late in the war, colder ones. The Japanese willingness to throw away their lives made being a tanker a dangerous place,  but if it followed the same pattern casualties in the ETO did, than being a infantrymen was by far the most dangerous thing you could be.

 

The website www.radionerds.com was a huge help with this post. Not only do they host a lot of info on Radios, but they have the manuals, data sheets and pictures to go with them. They also have a whole site dedicated the Army’s amusing PS Magazings.

Sources: Armored Thunderbolt by Zaloga,  Sherman by Hunnicutt, Combat Lessons, The Rank and file, what they do and how they are doing it 1-7, and 9.  The Radionerds website  TM11-67

#10 Tank Infantry Communication: They Couldn’t At First, Shocking But True!

Tank Infantry Communication: That’s Right, Tanks, and Infantry radios Did Not Talk to Each Other!

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The only decent image I could find of the phone on a tank( I found more)

M4 tanks, and US Armor in general couldn’t talk to the infantry they were tasked to support. When I first read about the communication problems between tankers, and the ‘doughs’ they were fighting with I was surprised. It’s hard to believe in today’s world; talking to people inside a vehicle right next to you would be a problem, like send a text right bro? Well not back in the forties, they did have two-way radios, but the technology used vacuum tubes, because transistors had not been invented, and they were not very reliable and had a limited number of radio frequencies they could talk on. They also had the problem that tank radios and infantry radios did not share frequencies or even band!

M4_Sherman_Tank_30_96th_Division_Big_Apple_Ridge_Battle_1945_Okinawa
This M4 Composite hull supporting the 96th ID on Okinawa has an infantry phone, and there is Dough on it.

So Shermans would be sent to support Infantry, usually, a separate tank battalion would send a platoon over to regiment of infantry, often the battalion would be assigned to the same infantry division for a long period of time so they could get used to working with the same people. This helped, but in combat, they still had real communication problems, no matter how long they had worked together in training. This problem didn’t really come to the top until after D-Day when the Sherman was supporting infantry in the bocage country, and close cooperation was needed. A platoon could be broken down further to support smaller units as well, and it wasn’t unheard of for a single tank to support a company, though they really tried to at least keep tanks paired up.

Things would normally go well communication wise before the shooting started; at least the tank commander would be riding with his head stuck out; so he could talk to the infantry riding on his tank or walking around it. A savvy infantry officer may be up on the tank talking to the commander. Once the tank started taking enough fire for the crew to close those hatches, everything changed. No amount of yelling or even banging on the tank would get the crews attention. Since the tanks and infantry were not on the same radio nets, if they wanted to get orders to the tank through the radio, they had to radio up to battalion or regiment level, get someone to find the tank battalion commander or someone who could talk to the tank on the radio, and then hope, they could get that actual tank on the net during the firefight. This did not work well. Often it took a man standing in front of the tank and waving his arms to get them to open up, this clearly was not an ideal solution either, and even when the commander did pop his head out, he had a very hard time hearing anything with his helmet on.

If the tank unit and infantry units got to train together and had been working together for a long time, this was less of a problem than a tank battalion assigned to a new infantry division with no combat time and little tank/infantry training. This lack of combination became a clear and prominent problem in the bocage fighting in Normandy when infantry wouldn’t be able to warn the tank they were working with of an imminent threat in a timely manner. The infantry would often be forced to fall back from the tanks leaving them alone, and easy targets for enemy infantry close assaults.

Various solutions were improvised in the field; they tried using the infantry’s handy talky from inside the tank, but the tanks electrical system caused too much interference. They also tried giving company level infantry headquarters spare tank radios, mounted to a backboard, but they were really too heavy to be practical, and not common enough to be all that useful. Some smart tanker figured out if you poked the handy talkie’s antennae out of the hatch, it worked, and that was the best solution for a little while. They also tried rigging up field telephones, with spools on the back of the tanks to let out the phone wire as they advanced, but the wire broke easily and restricted how the tank could move.

TB_SIG_192_p2

The best solution was worked out by Operation Cobra, and many tanks went into combat sporting it. The fix was mounting an EE-8 field telephone in a .30 caliber ammo box on the back of the tank. This phone was wired into the tanks intercom so anyone could walk up and say, “Hey! You blind Sonsobitches!! Shoot the machine gun nest over to the right, that house you’re shooting up is empty, you stupid bastards!!” or something to that effect. This, of course, could get the infantry guy, who wanted to talk to the tank shot, since he had to stand up behind the tank, but they still haven’t come up with something better, and M1A2 Abrams tanks are getting infantry phones installed on them now.

The Marines came up with this solution as well, but faster, since they used the M4 for much less time than the Army. They did come up with it around the same time as well, in July of 44. They found it essential for working in close with the fellow marines. The Japanese at this point was using man-powered shaped charges on a pole, or magnetic mines, and the tanks really depended on the infantry around them to be their eyes. Marine tanks operated buttoned up once the shooting started, without the phone, they were much less effective.

Here’s a link to a little Army video on the subject of the tank, infantry team. 

Sources: Armored Thunderbolt by Zaloga, Yeide’s TD and two separate tank battalion books, Sherman by Hunnicutt, Combat Lessons, The Rank and file, what they do and how they are doing it 1-7, and 9.  Oscar Gilbert’s, Marine Tank Battles in the Pacific,  Son of a Sherman by Stansell and Laughlin, M4 Sherman tank at war by Green,  the Lone Sentry,