SCR-508 WWII tank radio description and actual on-air operation

(Jump to 12:49 to skip the description and see the radio on the air)
This WWII tank radio is so cool, it is peeing ice cubes. A like new SCR508 radio installation including a full complement of FT-241 radio crystals, on a never issued FT-237 mount, with a New Old Stock BC-604, transmitter, a NOS BC-603 receiver and a second BC-603 receiver that is practically like new. As you can see, it all works perfect. The best SCR508 military WWII radio you will EVER see - working as it did in WWII, 70 years after the war ended.
This SCR-508 radio system was used from 1942 for tanks like M5 Stuart, M7 Priest, M10 Wolverine, M24 Chaffee, M4 Sherman, M7 MT, T1 heavy, M36 Slugger, M4A3E2, M4A3E8 Sherman, M6, T20, T25 AT, T29, M26 Pershing, T23, T28, T32, M46 Patton, T34, T95. (Source: radiomuseum.org)

[@midsouthexpress]

I love those radios. I love hearing the loud click of the relays and hearing the motor spin up on transmit. I wish I could find one just like that for the 2 meter band.

[@shockwave5544]

me too

[@oldsoldier181]

Just stumbled across this video. As a relatively new ham, this is amazing to see. As someone who, 30 years ago, used military radios fairly regularly-both mounted and man portable-this is pretty cool to watch, and hear. Great job!

[@n1kkri]

I bought a 604 from Fair Radio Sales back in 1966 when I was 15 years old. I made a 15m contact with it. I didn't have the dinamotor and used a HV supply. It was a blast. Ken

[@JakeTheTankmaster]

One of the best radios of the period. Great showcase of this marvel.

[@c.hundley9714]

Thanks for sharing these beautiful works of art.

[@seaningram4434]

"Knife" and "Variable" were callsigns used in the Tom Clancy movie "Clear And Present Danger"

[@LifeIsTooShortForQRP]

Sean Ingram You're right! Knife: "Chicken is in the pot!" Variable: "Cook it!!!" kzbin.info/www/bejne/mGrYYamsrpeKoJY

[@warplanner8852]

..in the book as well.

[@steelscooter]

Fantastic video. Hearing these radios as they would have sounded in WWII is incredible.

[@LifeIsTooShortForQRP]

SteelScooter Thanks!

[@JA-fy1bn]

That is just to cool! Excellent video and beautiful equipment. Thanks!

[@assidiq178]

1. play this 2. jump into 12:49 (as said in the video 3. open another youtube tab and search 12 HOURS OF A BATTLE WWII SOUND EFFECTS 4. pause it 5. open another youtube tab and search War Sounds - 10 Hours - Distant Artillery - As Real As it Gets!!! 6. play the WWII sound (or your favourite) 7. ???? 8. Profit

[@Centar1964]

+TheGAMER178 I did this.....too funny!

[@MM0SDK]

+TheGAMER178 I did this too. Thanks lol. Peeoowww...... boom.

[@panduwidagdo7051]

Ah better add this B-17 "Bomber Sound for Sleeping".

[@raf.nogueira]

I don`t undertand nothing about Radios , but this is beautiful!

[@maryrafuse2297]

As a wireless # 19 owner I look at this radio with great interest. Nice radio.

[@glmemory]

Very nice. I love these war radio sets. Love to read about and learn about it all. Owning one of the many different setups is not my thing, but I'm glad there are those out there who do!

[@dneitzke]

once in 10 lifetime finds Awesome!!! Re-cap that babe and run it with a 40 ohm ant. and then you'll have one fantastic radio. Thanks for sharing!

[@zubirhusein]

Wow this is amazing, I love old military equipment

[@SMGJohn]

Sounds awesome, old analogue things are awesome

[@svendcarlsen8543]

Nice radioset - I used this set in 1962 in our recc. unit at Jydske Dragon Regiment in Denmark. We had only 1 receiver in the set, and it worked excellent. We only used one crystal in the unit and started the unit up with fine tuning the antenna - we had one mounted on the truck and if we had a fixed position we used an extra higher antenna - and again fine tuned this antenna before we could start using the set. By using the transmitter we had to wait some seconds for the green light on the transmitter that we had full power on the transmitter and then we could send our messages.The crystals were pre-installed from the Regiment and we were not allowed to change the crystals.

[@LifeIsTooShortForQRP]

Excellent! I always love to hear from people who actually have used equipment shown in my videos in their professional life. Thanks for letting us know. Yes I can see why they made you wait a few seconds before speaking in the microphone after keying up, the transmitter has directly heated filament tubes, and those filaments are only switched on when actually transmitting. It takes a second or so before such tubes reach full emission, so if one would start to talk right away the first words transmitted might be cut off. The other reason is the heavy dynamotor used in the transmitter. When keying up, the DC supply voltage might drop momentarily during dynamotor startup. You can actually observe this phenomenon in my video, the power supply I am using is a bit on the light side to handle the inrush current. The same would happen in actual military vehicles depending on the condition of the vehicle battery and length of the DC cables. So this inrush current (that is, the voltage dip that it creates) will also contribute for the tube filaments to take some time to reach full emission. Cheers!

[@fourfortyroadrunner6701]

I had one of these--which worked. Basically, a Gigantic, overweight, FM CB radio, and likely not any more range, even though a bit more power

[@jimpokorny4598]

Excellent Old Rigs you have there. Thanks

[@c.hundley9714]

This requires massive talent. Love the videos. Awesome job!

[@LifeIsTooShortForQRP]

Thanks!

[@TerryMcKean]

Nice!... and with two receivers, one can connect each RX to either a horizontal or vertical oriented antenna for diversity reception.

[@klbird]

Thanks for the tour. Great piece of equipment for its day.

[@thrillscience]

Beautiful! Thanks for sharing this.

[@budleyca1]

Nice score, really enjoyed this, thanks for sharing...

[@artwallace9323]

I literally grew up playing with a BC 603 receiver, it was set up to get car phone and police bands.

[@rádiosantigos1958]

That is a very nice radio. Congrats!

[@allenmiddendorff2068]

I love the rabios.

[@MikeG-ox4nf]

Excellnt job

[@cbeagle]

SCR stands for Station Complete Radio. The individual transmitter and receiver's are named BC.

[@helraiser666painkil]

That's a really nice radio you've got and you've said that it is from WW2 but it looks vertually brand new and in very good condition for it's age and everything I really like the army radios and maybe some day I'll have the money to actually buy one and operate it on the amateur radio bands and it would be very interesting to see how far I could get if I tuned it up on the 40 and 20 meters it would be great to have a radio like yourself. Thanks and best 73's. Stephen M3SNV 73's.

[@chopperboi89]

This is one of the best sets I've ever seen!

[@Inkling777]

There's an interesting contrast between this tank radio, a massive and heavy steel beast, and the radios they put into aircraft, which were compact, light-weight and aluminum. I know because I owned the 80 and 40 meter Command sets as teen ham. Back then you could pick them up by mail order for about $6. I just checked Fair Radio and all the command sets seemed to be gone. All that is left is the MD-7/ARC-5 AM modulator and it is out-of-stock and would cost $250. None are presently on sale on eBay either. Wish I had kept mine.

[@MikesMovies]

what a fascinating video, thanks

[@SgtRock-cr2sh]

SCR stands for SET COMPLETE RADIO officially

[@katana200901]

It was cool!!! Thanks for this video!

[@nunyabizness199]

Amazing find !

[@rogersmith9808]

Great video and quite interesting!! ......... Roger (W9RHS)

[@MrBugsier5]

would work fine in europe we use also fm on the cb bands . (27mc)

[@nor4277]

You are a lucky man having that great piece of history,I wonder how the capital's are .I wouldn't be surprised if they dried out of leaked ,they are pretty old.I hope this set will be around and working for a long time.

[@fuzileiro1974]

SCR stands for Set Complet Radio, not Signal Corps Radio. Info from american military radio museum.

[@LifeIsTooShortForQRP]

I think we are both right. In the book "Getting the message through: A Branch History of the U.S. Army Signal", it reads on page 172: "The designation SCR originally stood for "Set, complete radio" but has come to signify "Signal Corps Radio"" books.google.com/books?id=noEBBvjbwVMC&pg=PA172#v=onepage&q&f=false So it appears that in a later phase the term "SCR" was generally adopted to indicate "Signal Corps Radio". I prefer to use the term as accepted in the later phase as this is the way it was used by the military in the most relevant period, being 1944 and 1945, not the early years. Cheers.

[@margaqrt]

Not much practical amateur value, other than chatting with your friend on the CB band. I guess you could use it to call breaker 19. Nonetheless a pretty impressive piece of living radio history.

[@annettepattongraham3602]

I bet it will get down on 27.025! Lol

[@PaulHigginbothamSr]

I think you might really clean the sound up on this beautiful radio, by changing out the capacitors, they have gone bad, it sounds like.

[@warplanner8852]

I assume - and for the benefit of other viewers - "MO" and "LO" means master oscillator snd local oscillator respectively.

[@maninthevan53]

lol wow, you are amazing ,just looking at this I am lost lol

[@meme-ei3yq]

Its like that movie frequency

[@douro20]

I wish I had a dynamotor for my BC-453-B so I won't have to try building a power supply for it...

[@psveditx1273]

I want somehow to listen to old people 1960s in radio

[@yardleybottles6025]

I don't need testosterone replacement after watching this

[@rohnkd4hct260]

had one of those receivers

[@NanashiCAST]

some people still use this for their discord calls

[@joelee24]

Very interesting stuff thanks for sharing, but please excuse my ignorance that one thing I don't understand, why use dynamo as power supply ? as far as I know dynamo generates electricity via engine drive that’s how it work on cars, but you simply flip the switch to turn the thing on, or it is attached to a motor ? sorry I must be very stupid to ask !

[@nonglantayai917]

wow! good.

[@thepuma2012]

wow, interesting

[@meme-ei3yq]

Dad dad it's 2018. How is 1945

[@zeber127]

Супер аппарат!!!

[@jefferyrightmire9520]

Where can you find these types of radios --incredible.

[@LifeIsTooShortForQRP]

Jeffery Rightmire Thanks for the nice words. All subsystems were acquired separately over time.The BC-604 transmitter, the two BC-603 receivers, the FT-241 crystals, the dynamotors and the manual came from eBay as stand-alone purchases. The FT-237 mounting (VERY hard to find!) came from the annual Dayton hamfest (the guy I bought it from was using it to weigh down his tent...) Of course a massive restoration effort went into the whole as well; it is not a matter of hooking it up and off you go. For example, the BC-603 receiver on the far right was brought back from the dead, some ham had butchered it (trying to modify it to AM and 10 meter, they should go to jail for that), I restored it to better than original condition (as you can see in the video, the far-right BC-603 receiver now works better than the virginal one on the left!) Also the FT-237 mount was completely restored, including the ceramic terminals and a new power cable. Then the whole installation was precision aligned according to the procedures as described in the manual. Hope that clarifies it!

[@TerryMcKean]

03:46 Definitely an awesome set of crystals with that rig. Are the crystals fundamentally cut for the frequencies indicated on the top of them, or are they cut to lower freqs and multiplied by the TX RF circuits to that indicated frequency?

[@LifeIsTooShortForQRP]

Good question. The fundamental frequency of the crystals (type FT-241) for the BC-604 transmitter is in the range 370 kHz to 516 kHz, depending on operating frequency installed. The crystal is then phase modulated and subsequently multiplied in a series of doubler- and tripler stages to a total of 54 times. So for example, 21.4 MHz operating frequency (which is the frequency printed on the particular crystal) is actually a crystal having a very low fundamental frequency of 396.3 kHz. This was done to get sufficient FM deviation, as phase modulators were still in their infancy in those days, generating only minimal phase changes. By using such large multiplication factors, they overcame this shortcoming to still got enough FM deviation at the operating frequency. Cheers.

[@TerryMcKean]

@@LifeIsTooShortForQRP Right on... thank you...... This reminds me of years ago when I had a Gonset Communicator 2-meter rig that I had picked up along my journey through submarine school in Groton CT. It included a little crystal-holder/adapter featuring a microphone amp/varactor diode circuit that was connected across the transmitter's crystal and would vary the crystal's freq a tiny bit at an audio rate and the multipliers in the tx's circuits would process that and kick out a nice FM signal into the 146.34/94 Hartford repeater. The 94 side of the repeater came in ok via slope-detecting with Gonset's AM rx. That was back in 1976. :-)

[@florisb690]

Wow man this is amazing! I got a question about the crystals, is it illegal to send a signal over it? Here in Europe they say it's very illegal to broadcast a signal over it. They say it can put all the WiFi/4G/5G down out of the air is this true?

[@LifeIsTooShortForQRP]

This radio covers 20 MHz to 28 MHz in 100 kHz steps. For the BC-604 transmitter, the frequency is determined by a crystal which is pre-chosen by the operator from a set of 80 crystals (see the video). The BC-603 receiver can be tuned anywhere in that band since it uses a variable (i.e. tunable) frequency setting (see the video). Since 21.0 MHz to 21.450 MHz is actually a ham band, the radio can be operated legally on the channels 21.1, 21,2, 21,3 and 21.4 MHz, assuming you have a ham ticket. The band 24Mhz is also a ham band (24.890 to 24.990 MHz, so it also could be operated legally on 24.900 MHz, assuming you have a ham license for those bands of course. The radio will not interfere with WiFi , 5G, 4G or 3G because those frequencies all are located in bands above 700 MHz, which is way above the 20 MHz band in which this equipment operates. So no, it won't cause any problems with modern phone gadgets. Hope this helps.

[@florisb690]

@@LifeIsTooShortForQRP do you live in Holland I want to contact you.. Can you repair our Dodge radio??

[@florisb690]

@@LifeIsTooShortForQRP hey man can I contact you, do you live in Holland? Can you repair our radio?

[@LifeIsTooShortForQRP]

Hello. No I live in the US. No I don't repair for third parties, I have too much projects here for myself already, sorry

[@CharlesvanDijk-ir6bl]

Soldering iron and a set of screw drivers and you could tinker for ours.

[@Naksgaming]

What was the procedure for tank communication was it using “major” “minor” callsigns

[@joelee24]

I think I can answer my own question, it is the high voltage required by the tube radio ha ! solid state inverter hasn't been invented, or powerful enough to drive the radio back then.

[@LifeIsTooShortForQRP]

Yes, you are correct, solid-state invertors did not exist yet during world-war II (the first usable power transistors for that purpose became available mid- to late fifties). So they used rotary inverters , also called dynamotors. It is basically a motor that drives a dynamotor, all on the same drive shaft and in the same housing. They do the job, but they are heavy and noisy. But inside a tank there is so much noise you wouldn't even notice the noise from the rotary inverters, 🙂

[@mattm5941]

So it’s basically a big ass cb radio

[@fourfortyroadrunner6701]

I've said the same, except it's REALLY wide band FM

[@yokumato]

Awesome! Now some dumb questions; how do you find the reliability and repair ability of this radio vs. more contemporary comparable sets? How about usability too?

[@LifeIsTooShortForQRP]

+yokumato Hello! The manual (downloadable from the internet) describes the theory of operation in detail, and also offers repair and alignment procedures. Of course basic knowledge of tube equipment and radio concepts in general would be needed before you attempt repairs. In terms of reliability, that is a hard one, but one could conclude that reliability must be pretty good for a radio that still works after 75 years of its manufacturing date. To compare, I'm pretty sure my $3000 ham radio won't work any more 75 years from now. The LCD display will have turned black; the flash memory (and other non-volatile memory components) will have lost their data and the VLSI chips will most likely have failed by then due to metal migration and cosmic ray damage. Basically those are throw away radios, gone beyond repair by then. But the SCR-508 in this video might still work; at the very least it will still be repairable!

[@yokumato]

Thanks for the reply!

[@Sophie15092011]

WW II CB

[@shoominati23]

Have any of you guys got a working 22 set?

[@garymckee8857]

Where do you obtain such equipment in new condition?

[@coondogtheman]

but could you change out the crystal for one that let's the radio tune regular FM or is that frequency range all it can tune?

[@CondoreComputing]

even if it could tune to higher frequencies it is a vary wide band receiver so it needs an FM signal that has a lot of frequency deviation.

[@darryllennane]

Hi there, I am restoring one of these sets and have mine running now. I am mainly interested in the interphone side of it as it is going in an M8 armored car. Does your dynamotor run all the time when in interphone mode? In radio mode, the dynamotor runs when I key the microphone but I understand that in interphone mode the dynamotor runs all the time, without having to key the microphone. I'd be curious to see if this is the case on yours. Thanks Darryl

[@LifeIsTooShortForQRP]

Yes, it works like that for my radio as well!

[@darryllennane]

Hi there So the dynamotor on your BC-604 runs all the time in Interphone mode? Thanks Darryl

[@SpectreOZ]

Have you ever received UK FM CB on those receivers?

[@LifeIsTooShortForQRP]

+SpectreOZ Good question, but no - the receiver is way too wide for that (100kHz). Also it expects a large FM deviation from the transmitting station to make it through this receiver. A CB FM station is very narrow in deviation, in this receiver it would therefore sound like a carrier without modulation. Maybe if the CB signal was real strong without any adjacent stations on other CB channels, and you would crank up the audio volume of the BC-603 receiver to maximum, you might hear the modulation from the Cb station. But under normal conditions, with many other CB stations on the band, and signal fading happening, you would not be able to hear the modulation. Cheers.

[@maninthevan53]

original talkback lol

[@LifeIsTooShortForQRP]

+danny blackhorse That's correct - it is basically a talkback feature! :-)