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 Post subject: Old tubes from Ebay . Transport issues ?
PostPosted: Mar Mon 05, 2018 9:58 pm 
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Joined: Apr Sun 16, 2017 8:25 pm
Posts: 19
Hi ,

After a successful restoration of my Atwater kent model 42 (with help from the forum team ) I got all winded up
and bought a Atwater kent model 20c on ebay and got it sent from US to Sweden. The price was god even including the
shipping cost. Atwater are very rare in Sweden. When I got the set all tubes had a broken filament. The seller did not mentioned
any status of the filament's so they might been broken from the beginning.

I need 5 new 01 Tubes and hesitate a little to buy new from US and risk that they beak during transport f to Sweden.
Any experience from "long " transport of tubes in mail ? I bought several sets in sweden via normal postal service and have quite
positive experience when it comes to tubes surviving teh transport (ie filament )

It is not possible to get any 01 tybes in sweden , any idea of a "European" replacement ?

regard


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 Post subject: Re: Old tubes from Ebay . Transport issues ?
PostPosted: Mar Mon 05, 2018 11:53 pm 
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Joined: Jan Thu 01, 1970 1:00 am
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Location: Livermore, CA
Certain transmitting tubes have filaments that can break in shipping. I've mailed 01A's to Europe and never had a filament break.

To replace 01A you need a 5 volt triode tube. Believe Europe had some 4 volt triode tubes? Exact filament voltage isn't critical as input to filament can be reduced. Even #30 tubes with 2 volt filaments can be used in place of 01A. Filament rheostats won't have the same action as current is lower for a 30.

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 Post subject: Re: Old tubes from Ebay . Transport issues ?
PostPosted: Mar Tue 06, 2018 1:40 am 
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Joined: Jan Thu 01, 1970 1:00 am
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Location: S. Dartmouth MA 02748-1225 USA
There is a remote chance the pins of the tubes will need re-soldering...

Unless the broken filament can be seen inside the tube.

The set probably traveled in the cargo hold that can reach -40F... That would contract the dumet wire lead in the tube base.

Most tubes of the 20's had solder in the pins of a high tin content. Over the years the tin becomes crystalline and a non-conductive condition will occur with the wire lead often releasing the wire.

Because the high tin content the melt point will be high, so add new 63/37 solder while applying heat then extract the mixture. Clean the pin and wire with the pointed blade of an Exacto knife. Add a tiny drop of active liquid rosin flux then solder. Use a heat sink on the pin, overheated pins will blister the Bakelite and loosen the pin in the Bakelite.

I often use a flat file across the bottom of the pin and remove some of both the old solder and the brass pin. That exposes a larger opening to manipulate the Exacto blade. FWIK there is no socket that a slight shortening of the pin would be a problem

Oh, FWIR working with new equipment destined for Europe there are strict ROHS regulations, I hope you can get a suitable solder...

YMMV

Chas

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 Post subject: Re: Old tubes from Ebay . Transport issues ?
PostPosted: Mar Wed 07, 2018 11:59 am 
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Joined: Nov Mon 02, 2009 7:01 am
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Location: Lincoln City, OR
Greetings to Mrbakelit and the Forum:

Shipping fragile tubes can be done; the trick is to get the sender to use the proper packing technique. Here is the proper technique (from one of my earlier posts):

Quote:
I shipped some WD-11 tubes which are noted for their fragile filaments with no problems. Here's how I did it:

The first thing is to remember what you are trying to do and that is reduce G-loading on the tube. This brings us back to Newton's F=ma. For a given force, the smaller the mass, the larger the acceleration. Tubes, even your 25T and especially the WD-11, don't have much mass (large external anode transmitting tubes excepted). Therefore, the trick is to increase the effective mass of the tube. Start by finding a carton that is a fairly good fit for the tube. You do NOT want much space left over for packing in this carton. Pack the tube in this carton with stiff bubble wrap or something similar so that the tube is tightly mechanically coupled to the carton.

Now, find some lead weights. I used two fishing sinkers for each of the WD-11's; you would need something a bit heavier (or more of them) for a 25T or a 250TH. Tape the lead weights securely to the outside of the carton with the tube in it. Now, you have a larger mass which is more difficult to accelerate. Now, find a much larger carton and pack the first carton inside it with plenty of very soft packing on all sides. The fiberfill stuff would be good or anything similar that is fluffy and light. Do NOT jam this stuff in around the inner carton.... the inner carton must be free to move around somewhat within the larger carton without contacting the sides, of course.

Close up the outside carton and ship. Any applied force from outside will be attenuated by the fluffy packing and will be less able to produce high accelerations in the massive inner carton holding the tube. The same principal will also provide vibration damping. The weights are important... see the equation.


If you can get your shipper to do this, you should be able to order your tubes with confidence. As someone else mentioned, the EU is ridiculously paranoid about lead; iron weights would work as well but must be physically larger for the same mass, of course.

Regards,

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Jim T.
KB6GM


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 Post subject: Re: Old tubes from Ebay . Transport issues ?
PostPosted: Mar Thu 08, 2018 12:15 am 
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Joined: Jun Fri 19, 2009 6:34 pm
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Location: Long Island
Be careful to get the right tubes for the set. In the US we started with 01, 201, and 301 tubes which have 1-ampere filaments. About a year later, RCA came out with the 01A, 201A, and 301A tubes which have 250-mA filaments.

The AK 20C is designed for the "A" tubes (250-mA) filaments. The rheostats will not work properly and may be damaged if you put non-A tubes in it. Fortunately, 01A tubes are more plentiful and less expensive than the older non-A versions.

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 Post subject: Re: Old tubes from Ebay . Transport issues ?
PostPosted: Mar Fri 09, 2018 1:44 pm 
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Joined: Sep Thu 14, 2006 3:27 pm
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Location: Carmel, Indiana
My suggestion is to buy all of the tubes of the same brand. The two most reliable and best quality brands of 1920s tubes are RCA and Cunningham (RCA/Cunningham). The best setup would be using all UX-201As and a UX-112A for the final audio output. Thankfully, RCA and Cuningham tubes are still found in abundance.

Image
Typical RCA 01A tube. Make sure that the glass is bright silver and not milky white.

The filaments of all of your tubes could have been damaged during shipment but I rather doubt it. I can't believe that "ALL" of them failed during shipment. I rather suspect that they were all burned out long before that radio was ever sold to you.

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Michael Feldt
www.indianaradios.com


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 Post subject: Re: Old tubes from Ebay . Transport issues ?
PostPosted: Mar Fri 09, 2018 2:54 pm 
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Joined: Apr Sun 16, 2017 8:25 pm
Posts: 19
Hi,

I now gotten deeper into the restauration and I agree with comment that the Tubes probably was defect from start and not Caused by
the shipment. Both reostats have burned windings so I assume that something bad happened with voltage on filaments.
Anyway, I found 01A tubes in the Netherlands .

/regard


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 Post subject: Re: Old tubes from Ebay . Transport issues ?
PostPosted: Mar Wed 14, 2018 8:24 am 
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Joined: Apr Sun 16, 2017 8:25 pm
Posts: 19
Hi ,

Got the Atwater Kent Model 20c restored and up and running. Don's think that there are that many of this type in Sweden.
Will search ebay for a new interesting project .

Thanks for all help and valuable inputs !

regards Roland


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