Author Topic: LF tube radio restoration  (Read 4358 times)

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Offline Martin.M

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LF tube radio restoration
« on: November 25, 2016, 07:30:36 pm »
Telefunken E108Lw4

from 10kc to 1.8mc in 6 ranges.
full tube radio
BFO
double conversion superhet receiver
Sensitivity  for 10 dB s/n

range 1+2 (LF) 0,5µV
range 3 0,45µV
range4 0,4µV
range 5+6 (500kc up to 1.8mc) 0,3µV

3 antenna inputs: high, low (60 ohms) and symmetric for Loop

filtering:
each band, input = 4 coils
IF1 (80 or 325kc related to the range) , both frequencys have a 6 coils filter
IF2 (525kc) there are 2 crystals for selecting the bandwith in 4 steps from +-.1 to +-4.5kc

about handling of the radio: on the front plate is to read 90kg  :)

first picture: begin
last picture: done, the old radio is now back to life.

greetings
Martin
 

Offline Martin.M

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Re: LF tube radio restoration
« Reply #1 on: November 25, 2016, 07:31:47 pm »
continue  :)

 

Offline Martin.M

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Re: LF tube radio restoration
« Reply #2 on: November 25, 2016, 07:34:26 pm »
done.

The oldie is so much heavy, we put it with 3 persons on the table..

greetings
Martin
 

Offline floobydust

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Re: LF tube radio restoration
« Reply #3 on: November 26, 2016, 02:38:36 am »
What a masterpiece! Unbelievable quality and all the diecast gear-driven band-switches. Seems to be circa 1957.
Reminds me of a time when cost didn't matter- "let's build something superb, a work of art" was the engineering philosophy.
I'd love to DX with it. Great restoration Martin.
 

Offline Martin.M

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Re: LF tube radio restoration
« Reply #4 on: November 26, 2016, 06:36:54 am »
thank you  :)

the band switches are 23 pcs. with 6 steps, driven in 2 lines by the geartrain from the knob. Addittional one pc. outside from the tuner chassis for the 12 little bulbs (6 steps x one left and one right)   in the front. The most of the switches are to swapp filter coils, and related to the band the frequency of the IF1 and the second oscillator. picture Telefunken-10: this is a germanium diode ring mixer OA154Q. The tuning knob is pushed a coarse and pull a fine tuning by gear ratio. The radio have a crystal based calibrating oscillator with harmonic of 25kc for low bands, 200kc for high bands.
The oldie is a great performer in DX, also it can receive the Grimeton SAQ directly. Ideal combination with a shortwave boatanchor to have the complete AM bands. The shortwave brother from Telefunken is the E104, I dont have one, but EK07 (see https://www.eevblog.com/forum/rf-microwave/140-lbs-of-radio-(restoration)/ ) from Rohde+Schwarz will do the job also perfect.
I have seen on a very old picture 3 of this E108 working in the german weather headquarter, there was plates with citiy names on the radios like NY, Moskau, ....
The frequency drift of the 1. oscillator is (by manual) <26Hz / 1hour, in the test with a rubidium locked counter it was below 20Hz, a warm up of a half hour is required to get that.  It is full equipped with SQ tubes of long life time. There are no electrolytics, all is build with large metal paper Cs instead of them.

E108Lw4 is part 2 of my project "vintage boatanchor radio tower". The next restoration is the greatful field strenght measuring receiver HFH from Rohde+Schwarz. following a second EK07. then I will stack them on a cart with rolls.

greetings
Martin
« Last Edit: November 26, 2016, 08:18:34 am by Martin.M »
 

Online VK5RC

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Re: LF tube radio restoration
« Reply #5 on: November 27, 2016, 09:39:10 am »
Again lovely work, but 140lbs! You need a very strong table for that.
What is the ?"Circo" spray can?
Thanks for sharing.
Whoah! Watch where that landed we might need it later.
 

Offline Martin.M

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Re: LF tube radio restoration
« Reply #6 on: November 27, 2016, 10:20:22 am »
this is acid free synthetic oil,
it was not possible to rotate the bandswitch / gear train. This oil made it clean and easy to use.

about 140lbs: that means the R+S radio.

Telefunken E108Lw4 is more heavy then a EK07D.  :)

Part3 of my vintage radio will be the HFH field strenght meter receiver, the R+S with the beautiful Loops.
Restoration is now running , see https://www.eevblog.com/forum/rf-microwave/field-strenght-meter-receiver-rs-hfh/

greetings
Martin


« Last Edit: November 27, 2016, 10:46:45 am by Martin.M »
 

Offline TimFox

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Re: LF tube radio restoration
« Reply #7 on: November 27, 2016, 07:58:45 pm »
Can you list the tube complement?
 

Offline Martin.M

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Re: LF tube radio restoration
« Reply #8 on: November 28, 2016, 03:57:38 pm »
E108 works with some EF805s, ECC801s, EL84 and 2 gas stabi.  (SQ version)
EF85, ECC81, EL84 and 2 gas stabi (following the manual, version with electrolytic C)

greetings
Martin

 

Offline Martin.M

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Re: LF tube radio restoration
« Reply #9 on: April 02, 2018, 12:15:24 pm »
I found in the netherlands a nice E104Kw4
this is the shortwave brother radio of the E108Lw4, in same case.
 

Online VK5RC

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Re: LF tube radio restoration
« Reply #10 on: April 10, 2018, 11:53:42 am »
Same mass? Visit the chiropractor and reinforce the floor!  Boat (Destroyer class ship) anchor envy :-+
Whoah! Watch where that landed we might need it later.
 

Offline Martin.M

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The following users thanked this post: VK5RC, GerryBags

Offline GerryBags

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Re: LF tube radio restoration
« Reply #12 on: April 26, 2018, 09:33:23 pm »
Beautiful piece of engineering, beautifully restored! Thanks for sharing, Martin. The "cart" that you are planning to put this on.. WITH SOMETHING ELSE?!?.... unless it's made by Mercedes and has air suspension in mayneed a little reinforcement!
 :-+ for keeping alive a very attractive slice of history.
 


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