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641M (con valvola DT4)

641M; Philips Italy; (ID = 5198) Radio
641M; Philips Italy; (ID = 2597609) Radio
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641M; Philips Italy; (ID = 5198) Radio
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Country:  Italy
Manufacturer / Brand:  Philips Italy; Milano (MI)
Year: 1937 Category: Broadcast Receiver - or past WW2 Tuner
Valves / Tubes 4: AK2 DT4 AL4 AZ2
Main principle Superheterodyne (common); ZF/IF 115 kHz
Tuned circuits 7 AM circuit(s)
Wave bands Broadcast only (MW).
Power type and voltage Alternating Current supply (AC) / 110-220 Volt
Loudspeaker Electro Magnetic Dynamic LS (moving-coil with field excitation coil)
Power out
from Model: 641M - Philips Italy; Milano MI
Material Wooden case
Shape Tablemodel, high profile (upright - NOT Cathedral nor decorative).
Price in first year of sale 750.00 ITL
Source of data Guida Pratica Antique Radio II (2000) / Radiokatalog Band 1, Ernst Erb
Circuit diagram reference Lange-Nowisch (?)
Literature/Schematics (1) Il Radio Libro (E.D. Ravalico) Edizioni Hoepli
Literature/Schematics (2) -- Schematic (Schemario degli Apparecchi Radio. D.E. Ravalico – Hoepli – 1944.)

All listed radios etc. from Philips Italy; Milano (MI)
Here you find 370 models, 306 with images and 229 with schematics for wireless sets etc. In French: TSF for Télégraphie sans fil.


Forum contributions about this model
Philips Italy;: 641M
Threads: 1 | Posts: 12
Hits: 2308     Replies: 11
philips: 641M; and DT4 tube
Alessandro De Poi

I have this radio. My model is without tubes and was probably modified.
I haven't found any information regarding the DT4 tube, which is reported to be used only in this radio (according to Erb's book and to the schematics).
Does anyone know some more information or a replacement for this tube? And some photo of the cabinet and/or the chassis?

Geza Bordi

Dear Sir,

Only two possibilities just.

The model is on a Hungarian isued service manual Philips from 1935. Possible it was made in the Philips hungarian mother company Budapest. I find it there, possible see in here You find 641M shema on it = in shown! I think Mr Herczeg or Mr Apsitos can help, the  two gentlaman have more experience pre War models. May have information tube DT4 and more.

About picture In Philips at here ,You can find all the pictures/graphic of Hungary made radios near 1100. Unfortunately Philpis is not used type no. only "fantasy names" is the early times. Please try it, maybe You find it by a NAME!

Best Regards

Géza Bordi


Alessandro De Poi
  3 Thanks for your reply.
The radio was made in Italy by Philips Italia (Monza - Milano). Unluckly the links aren't working: maybe are they wrong?
Anyway the DT4 tube was made from Zenith and I found a replacement.
Geza Bordi

May like and You have to roll down right /under Mr.Apsitos I pic and click/ PHILIPS RAJZ /, slow but work.The other like And HUNGARIAN RADIOS menu I hope as this working.Im not find any Philips radio made in Hungary 1936-48 is built in DT4 tube !!! I think I see all.Sorry, I dont know much about Zenit and Italian Philips models /It is much easy for You then for me... / Only some other, D type tubes seria,  I finid in later models under WWII. If I see some about the tuda DT4 Ill send it.

Best Regards 

G Bordi

Jacob Roschy
By investigating about the tube DT4_Zenith I came across this thread.
Information about this tube is very scarce.
By now is only known: double diode- pentode; heater 4 V 1.1 A;
Can someone tell more about this tube ? What kind of base does it has ? More about operating data ?
So far, the WE37F may be the successor and as well a good replacement for this tube.
Many thanks for your help in advance !  
I also wonder about the rectifier tube AZ2, since it's quite oversized. A normal AZ1 would be fully sufficient.
Btw., this model appears twice in the RM.O files:
Its very unlikely this model was ever sold or even made in Germany  !
Best Regards
Jacob Roschÿ  
Alessandro De Poi
  6 Dear Jacob.
thanks for replying.
We are on the right way: I think that WE37F is not just a good replacement for the tube I need, but is the right tube for my radio. In fact I was wondering why the socket base on the chassis was an Europe side contact base P, while the DT4 had an Europe 7 pin C7A, so in later models this tube was replaced with the successor WE37F.

This is DT4 socket:

About DT4, please see also the attachments here:

  • Characteristics of the tube are in the page: Ottodi (rete); Duo-Diodi, Diodi-Triodi e Diodi-Tetrodi (Binodi) (rete);
  • Whereas the socket is in the last attachment.
I'd bet that this radio has been built in Italy only, as some of Philips Radios which are listed in German Philips catalogue (for instance, those with tubes with Italian WE names, like 651 and 653) - but schematics were also in German.
Hans-Thomas Schmidt
  7 Dear tube and radio friends,

I have found some datas for the Zenith DT4 in a Hungarian book and listed here in the tube data page. The base of Mr. de Poi is correct, thank you.

Another nearly similar tube is the DT3 from the maker Zenith. It have only one diode.

Have a nice day,  H.-T. Schmidt
Alessandro De Poi
  8 It looks like I'll have to look for a WE37F.
Yes, also the DT3 is listed here:
while its socket is no. 75 here:
Hans-Thomas Schmidt
  9 Hello Mr. De Poi

I think, another possibility is a AF2, rebased, with 2 germanium diodes.

Regards,  H.-T. Schmidt
Alessandro De Poi
  10 Yes, this is what I've done indeed, to make the radio working again.
So, I'm not in a hurry to find the replacement, but would prefer having it.
Jacob Roschy
Dear Alessandro,
many thanks for your fast and comprehensive reply. Mean while Hans-Thomas has completed the DT4 data.
If you're sure, the WE37F is the right tube for your radio, Philips model 641M, then you may please suggest to change the tube lineup of this radio on its model page
from AK2 DT4 AL4 AZ2 à to AK2 WE37F AL4 AZ2.
As long as you don’t have a WE37F, the ideal replacement is an EBF2 heated via an autotransfo 4 à 6.3 volts.
There is still a second model 641M which from now on we may consider as the model with the old and original tube lineup AK2 DT4 AL4 AZ2.
I still wonder, why Philips used a tube from an other company in their radio. Philips was a tubemaker company, though later they made also radios that used their tubes. This let me suspect, wether ZENITH was probably owned by Philips.
Best Regards
Jacob Roschÿ 
Alessandro De Poi
  12 Indeed, Zenith was taken over and merged into Italian Philips sometime in that period. Also, both had their plant in Monza (close to Milan).
Probably the original tube lineup is the one with DT4, whereas latter series should have been using WE37F. There are also some variants of 641M with and without bakelite LS grill.

WE37F definitely suits my radio (I could finally remove the diodes and restore the circuit as it was before) which probably had been using this tube since beginning: the socket the radio is using is Europe-side contact base (not DT4's one). The radio works fine with the WE37F. Thanks for your help in solving this matter!
Philips Italy;: 641M
End of forum contributions about this model