DKE 38 restoration p1o3

[@AMStationEngineer]

"Das Volksempfanger", ist sehr gut! I'm going to really enjoy this project, WAY COOL, BOB! Back in the '70s, many invested their misspent youth into all things WWII, especially from the "German point of view", myself included. For more than 45 years, I've been fascinated by the advancements in electronics which their scientists and engineers made. The engineering lab where I worked had a wartime "Siemens Gaussmeter", which was every bit as accurate on the day they closed our division, as the day it arrived at a presumably secret laboratory of the Third Reich. The techs from the certification company which we used, AEI, could not believe that we never had our fingers inside of that beast for purposes of repair.

[@Andrewausfa]

Interesting little set, well worth getting back to original. I read that double valve/tube 'Ersatz mit' sentence as 'Subsitute with 2 12SH1'. Russian RF Pentodes, handily replacing components we can't get today like the use of Russian Germanium PNPs in our old transistors sets! Good to see you settling into the basement.

[@gd2329j]

Welcome back Bob . That moveable coil is the antenna coupling & so a volume of sorts . The regeneration control is the 200pf variable capacitor . The 600R preset with a 0.9uf cap across it is the cathode bias resistor . You will need 3 hands for driving this one .

[@gd2329j]

Note Regeneration control will not be linear / flat across the tuning range . When adjusting the regeneration control pulling of the tuning is not uncommon . With the regeneration control the more you add the more rf gain you get but the higher Q will gives you less bandwidth & you can push it up so much that the unit will squeal . Find your desired spot on the band move the regeneration control for a hiss & then back it off a tad & add antenna coupling , tune ,regeneration , adjust all a bit at a time up or down as required . The regeneration & antenna coupling controls are a balancing act for the correct bandwidth & RF gain for the volume required !

[@bandersentv]

Thank you for the detailed explanation of the regen control :)

[@bigshoerick]

Very interesting. I have this exact radio, however I haven't tried to power it up yet. I'll be watching you do this with great interest. Congrats on the house and getting all settled

[@UncleBensRice]

Hi 1:40 The 12SH1 is a copy of the german RV12P2000 multipurpose pentode, that was used by the Wehrmacht. After the War nearly no new produced components were avaible, so many people used old Wehrmacht parts and tubes to build small Radios, or to replace broken tubes in existing radios. The RV12P2000 was quite common and could be used as a rectifier, mixer, oscillator, amplifing stage etc. so many people used two RV12P2000 to replace the VCL11 in the DKE38. 2:39 In the case that use the replacement VCL11 you need to install that 1.2kOhm in parallel with the heater of the VY2 rectifier. 4:13 In some cases the missing or damaged shielding can cause squealing. 5:40 Yes you can run the radio on 110v but the performance will be quite poor. I would recommend using a variac and setting the voltage to 220v. 7:00 The control on the left side determines the coupling of the antenna signal into the circuit and controls the volume of radio. The control on the right side is a variable compression capacitor and controls the amount of feedback that is applied. 8:05 That's not a transformer. It's the choke of the powersupply. In 1943 the choke was replaced by a 2.5kOhm resistor to save production costs. Also the small black pot on the backside that is labeled Entbr. (for Entbrummer: hum pot) was replaced by a 300Ohm resistor. So it seems like that the spare chassis you've got was build during the war. 10:09 That's not the correct schematic for your DKE38. That's a version with an optional hf preamp. 12:18 That's the correct schematic. 12:55 The weird resistor is a hum pot located on the backside. You can access it with a flathead screwdriver through the backpanel. 14:17 200v or 250v are way to small don't use those for the two powersupply caps! You need to replace the caps with atleast an 350v rating! The orignial value is 385v as far as I remember. One really important mod you should do is to add a 330Ohm 2watt resistor in series with the VY2 rectifier tube. The original design did not include any protection from input surgecurrent and the VY2 is quite vulnerable for that. Even back in the 1950's the VY2 rectifier tube was hard get and today it's nearly impossible to find a working one. So please don't kill the one you have. Also make shure you use a 0.2A fuse for 110v operation and a 0.1A one for 220v. Hope that helps greetings from Germany

[@bandersentv]

Wow! Thank you for all the valuable information. I will definitely use components with higher voltage ratings. I am also thinking of adding a CL-90 or similar thermistor as a surge protector.

[@danvanlandingham3854]

I saw one in an antique store in Lampasas,Texas in 1989.They wanted around $100 for it.I wished I had bought it now."Himmler's Mouthpiece".

[@sewell2777]

Rather interesting to see the Swastika on both the tube and speaker. Adds a little more character to the set (it being an infamous character of course)

[@westelaudio943]

Of course, it's always propaganda when the other side does it ;) Yes, they used all that hard paper material to make it lightweight and the high impedance reed-type speaker to cut costs. No output transformer, field coil, delicate voice coil etc required, just the speaker coil between b+ and plate and you're done. The cheaping out had little to do with war effort though, those things were designed long before the war. They also made a "luxury" volksempfanger (VE301Dyn) with a big fieldcoil speaker and a metal chassis and no interstage transformer coupling. Still a TRF though. The idea behind the DKE was that it was so cheap and abundant that absolutely everyone could afford it, and it became by far the most popular radio in Germany. Of course those receivers were neither very reliable nor good sounding. The ironic thing is that because of their historic significance they sell for very expensive these days, despite being far less rare than other radios of the time. Many of them survived the destructions of war.

[@justsumguy2u]

Wow, you're really starting things off with a bang---what a zany little radio! From the schematic, it looks to be a two-band TRF set with no RF amplification of any sort---or is that what the triode section of the dual-purpose tube is for? Obviously the pentode section is the output, but no volume control? I'm lost on this one lol

[@bandersentv]

justsomeguytoyou I believe it's a regenerative type circuit. that movable coil controls the amount of positive feedback and will act as a volume control

[@justsumguy2u]

Thanks, I was really clueless on that. Looking forward to Part II!

[@dynamic881964]

Glad you are back !

[@ingussilins6330]

Simple and good circuit diagram! :)

[@wadehicks9270]

Wow that's one wild setup.

[@eduardopereira6598]

Good night sir This morning when I was going to dump the trash I found a Retex oscilloscope Kit model OS - 1E. I took it home and soon in the first test, when I turned it on the series light bulb, it lit with maximum light. Then I checked that something is wrong. My question is this: how can I check if the CRT is good? I have seen many of your videos and I think you are an expert on vintage TVs. Thankful if you can help me, since I have no experience in televisions, I am just a hobbyist in restoration of tubes radios. Thankful for your help. Eduardo Pereira (Torres Vedras - Portugal)

[@bandersentv]

You can check the for filament continuity with an ohmmeter. Beyond that you're going to need a CRT or tube tester. capable of supplying the correct voltages. It sounds like you have a shorted probably in the power supply. I think you should focus on fixing that then see if you can get a trace on the CRT.

[@eduardopereira6598]

Thank you! i think were the problem is. I go to chek the coper belt around the power transformer. If this belt have a short, the series lamp lighting with full brigt. After this i go to shek the rectification capacitors and so on. Gratings to you Eduardo

[@rivards1]

So, instead of an All-American 5, it's an All-Nazi 2?

[@umajunkcollector]

YA VOLT

[@videolabguy]

@@umajunkcollector That was "Hitlarious!"

[@videolabguy]

The symbol was usurped from the culture. It was originally indicative of the fall harvest. A wagon wheel would be wrapped in straw, set ablaze and rolled down a hill as part of the fall celebrations. The end result was that figure. It originally represented the circle of life. The you know who's tainted its original meaning.

[@sinewave4236]

Would that variable resistor be something to do with volume control ? I don't see how else that would be controlled

[@bandersentv]

I believe the volume is controlled by that moveable coil. It adjust the amount of regenerative feedback.

[@chrismielke219]

If your going to use that dual tube, you DO need to add that resistor is highlighted in orange where he indicates on that diagram... Fixx

[@Raul_Gajadhar]

Will to come back to this video later. Just one question tho. Why are you whispering? Gosh it is making me paranoid, it's like you are talking to your self and not to us. Maybe I just had a bad day, I'll watch this again later.

[@bandersentv]

i'm working late at night and do no wish to disturb anyone.

[@raybarron316]

Interesting that even the caps had eagles on them.

[@Thermionman]

neat looking tube

[@Thermionman]

yay! ....first restoration at new house :)

[@Buzz1151]

Hey Bob...After you fix the radio, I would like to request this song to be played on it....Spike Jones - Der Fuehrer's Face

[@umajunkcollector]

or some actual Adolf ranting

[@sewell2777]

And the caps too?! Damn those Nazis were sure very egotistical.

[@adrianschneider4441]

That type of receiver was called "Göbbelsschnauze" for obvious reasons.

[@DeadKoby]

What an interesting piece.

[@dennisperusse3837]

welcome back. :)

[@fuzzwack1]

YES YOUR BACK!!!!

[@zaprodk]

You're

[@gbowne1]

Any letter with two dots over it is essentially read like two of the same letter

[@PunkTiger]

In German, the umlaut (two dots) stands for the letter e. So ä is pronounced ae, ö is pronounced oe, and ü is pronounced ue. Note that there is no ï or ë in German as those diphthongs aren't common in the language. Hooray for my high school German classes!

[@fibrodad1354]

yay

[@jdf9984]

New Zealand

[@sinewave4236]

Ersatz = Substitute