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-   -   Can a 7625 Ceramic Planar Triode be soldered ? (http://www.diyaudio.com/forums/tubes-valves/181427-can-7625-ceramic-planar-triode-soldered.html)

Tubologic 19th January 2011 01:09 AM

Can a 7625 Ceramic Planar Triode be soldered ?
 
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Does anybody here have experience with small ceramic planar tubes ? I would like to use a 7625 planar triode but can't find a socket for it and the G.E datasheet doesn't mention any specific socket for this tube. It has small lateral pins (different from the 7077 who needs contact springs) which could be easily soldered on a PCB but I'm afraid to damage this (very expensive) tube by overheating it. Looks this tube was designed to be direct soldered into the circuit but I'm not sure. Your well informed advices are welcome.

nigelwright7557 19th January 2011 01:15 AM

Hold the pin on the top of the pcb with pliers while soldering underneath.
This will prevent heat reaching the tube.
Might be a two person job tho.

bigwill 19th January 2011 11:31 AM

That's the coolest little tube! What do the curves look like?

Edit: I found the data sheet on this site if anyone's interested http://www.classiccmp.org/rtellason/tubes.html

Not the most linear but not too bad, I want to play with some now :D

pjp 19th January 2011 02:37 PM

Tubologic, on the datasheet linked to by bigwill, it says "envelope temperature at hottest point: 250șC".

I think soldering will be a very risky thing to do. Those metal-ceramic joints are very fragile indeed.

I'm sure you can repurpose a socket from some other thing.

Tom Bavis 19th January 2011 03:02 PM

60/40 tin-lead solder melts at 183C. Tube seals won't reach the temperature of pins - should be fine. Don't use this if you must be RoHS compliant though... lead free is generally soldered at 250-270C.

Wavebourn 19th January 2011 03:26 PM

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I don't know about 7625, but 6S17K-V has electrodes made of silver coated titanium, no problems with soldering.

sycorax 19th January 2011 03:54 PM

Datasheets says Printed Circuit Board solder slugs:


Base Side contacts
Filament Vf 6.3 Volts / If: 0.24 Ampere / -: Indirect /
Description Ceramic and metal high mu triode intended for low-level audio applications. PCB solder lugs. Mu 80
Literature Essential Characteristics, GE 1973
- - Manufacturers Literature

sycorax 19th January 2011 04:06 PM

I think that 250 degrees Celsius is the maximum operating temperature, normally Ceramic tubes are High power High power and High temperature.

The pdf is a publication intended for radio hams. The tube is relatively immune to nuclear radiation so you can continue with listen to music after the blast:-)

Interesting pdf:

http://n4trb.com/AmateurRadio/GE_Ham...5%20No%203.pdf


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