[Hammarlund] Hammarlund Digest, Vol 129, Issue 7

Bob Camp kb8tq at n1k.org
Sat Oct 4 21:28:27 EDT 2014 

Hi

The tubes we (seemed) to be talking about are all low power receiving tubes. Sweep tubes / transmit tubes that handle a lot of power are a different animal. That goes double if something goes wrong with the biasing and they go “full on” for a while. They will indeed melt down in that case.

Bob


On Oct 4, 2014, at 9:01 PM, radiomanL <radiomanL at verizon.net> wrote:

> I do not think I saved any of them , I have seen horizontal output tubes that have been so hot the glass softened and the outside air pressure pushed the envelope in at that spot making a neat little cone that may or may not be open to the outside . most of them I saw were open to the outside air .
> 
> andrew
> kd5pnt
> ----- Original Message ----- From: <hammarlund-request at mailman.qth.net>
> To: <hammarlund at mailman.qth.net>
> Sent: Saturday, October 04, 2014 7:36 PM
> Subject: Hammarlund Digest, Vol 129, Issue 7
> 
> 
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>> Today's Topics:
>> 
>>  1. Re: Speaking of Tubes ...(Small Tubes) (kirklandb at sympatico.ca)
>>  2. Re: Unknown tubes and WW2 military secrets (k9cox at charter.net)
>>  3. Re: Need HQ-189 replacement BFO variable capacitor (Al Parker)
>>  4. SP-600 JX-17 with case (Bob Young)
>>  5. Re: Tube shields and heat (Robert Moses)
>>  6. Re: Tube shields and heat (Bob Camp)
>> 
>> 
>> ----------------------------------------------------------------------
>> 
>> Message: 1
>> Date: Thu, 2 Oct 2014 13:28:40 +0000
>> From: <kirklandb at sympatico.ca>
>> To: Hammarlund QTH LIST <hammarlund at mailman.qth.net>
>> Subject: Re: [Hammarlund] Speaking of Tubes ...(Small Tubes)
>> Message-ID: <BLU173-W511F58D1C0BDACDCCDB78FCFB90 at phx.gbl>
>> Content-Type: text/plain; charset="iso-8859-1"
>> 
>> Check out "Russian Rod Tubes" on google.
>> 
>> 
>>> 
>>> On Tuesday, September 30, 2014, Kenneth G. Gordon <kgordon2006 at frontier.com>
>>> wrote:
>>> > On 30 Sep 2014 at 22:55, Guido Santacana wrote:
>>> >
>>> >> What if... Solid state devices had not been invented back in the 50s.
>>> Tubes
>>> >> would have evolved into ....... Sub sub miniature tubes?
>>> >
>>> > Probably.
>>> >
>>> > I have always regarded the subminiature tubes first developed during > WWII,
>>> > as an extreme example of what COULD be done with tubes.
>>> >
>> 
>> 
>> 
>> ------------------------------
>> 
>> Message: 2
>> Date: Thu, 2 Oct 2014 13:38:34 +0000
>> From: <k9cox at charter.net>
>> To: "=?utf-8?Q?hammarlund at mailman.qth.net?="
>> <hammarlund at mailman.qth.net>
>> Subject: Re: [Hammarlund] Unknown tubes and WW2 military secrets
>> Message-ID: <yDgN1o00K0k9ncc01DgPTV at charter.net>
>> Content-Type: text/plain; charset="utf-8"
>> 
>> https://www.youtube.com/watch?v=6-D592VR4RU
>> 
>> 
>> 
>> 
>> 
>> 
>> Sent from Windows Mail
>> 
>> ------------------------------
>> 
>> Message: 3
>> Date: Thu, 02 Oct 2014 09:57:10 -0400
>> From: Al Parker <anchor at ec.rr.com>
>> To: "Peter R. Zidek" <zidek at charter.net>, hammarlund at mailman.qth.net
>> Subject: Re: [Hammarlund] Need HQ-189 replacement BFO variable
>> capacitor
>> Message-ID: <542D59B6.9000002 at ec.rr.com>
>> Content-Type: text/plain; charset=windows-1252; format=flowed
>> 
>> Hi Peter,
>> I can't get into my HQ-170 right now to look, but if you can send me a
>> pic and measurements, I'll see what I can find.  I have quite a few
>> small variables.
>> 73,
>> 
>> Al, W8UT
>> www.boatanchors.org
>> www.hammarlund.info
>> 
>> "There is nothing -- absolutely nothing -- half so much
>> worth doing as simply messing about in boats"
>> Ratty, to Mole
>> 
>> On 10/1/2014 10:07 PM, Peter R. Zidek wrote:
>>> Hi everyone
>>> 
>>> ,
>>> 
>>> I'm in the process of restoring a decent condition HQ-170
>>> 
>>> Everything seems to work but the BFO circuit because of a
>>> tuning BFO cap that fell apart.
>>> 
>>> Does anyone have a spare HQ-170 Variable BFO capacitor from
>>> a junker HQ-170 or know of a
>>> 
>>> source for a replacement.
>>> 
>>> 
>>> 
>>> Peter Zidek
>>> 
>>> ______________________________________________________________
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>>> 
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>> 
>> 
>> ------------------------------
>> 
>> Message: 4
>> Date: Sat, 4 Oct 2014 00:04:26 -0400
>> From: Bob Young <bobyoung53 at hotmail.com>
>> To: "hammarlund at mailman.qth.net" <hammarlund at mailman.qth.net>
>> Subject: [Hammarlund] SP-600 JX-17 with case
>> Message-ID: <BLU177-W278D2EE86328AE0BE35E24CCA70 at phx.gbl>
>> Content-Type: text/plain; charset="iso-8859-1"
>> 
>> 135.00 BIN ebay: grab it now
>> 
>> 191358079680
>> 
>> Not a looker but can't beat the price.
>> 
>> 
>> Bob Young
>> KB1OKL
>> 
>> 
>> ------------------------------
>> 
>> Message: 5
>> Date: Sat, 04 Oct 2014 18:00:17 -0600
>> From: Robert Moses <rhmoses at earthlink.net>
>> To: hammarlund at mailman.qth.net
>> Subject: Re: [Hammarlund] Tube shields and heat
>> Message-ID: <54308A11.4010805 at earthlink.net>
>> Content-Type: text/plain; charset=windows-1252
>> 
>> The rate at which chemical reactions such as those involved in the
>> degradation of tubes takes place increases 2.3 times for each 10 degree
>> C increase in temperature. Cooler is always better as long as it is warm
>> enough to work.
>> 
>> On 09/27/2014 12:54 PM, Kenneth G. Gordon wrote:
>>> On 27 Sep 2014 at 13:31, Guido Santacana wrote:
>>> 
>>>> As for tube shields, if they are not IERC shields, paint will not do much.
>>> Guido: on the basis of experiment, FLAT black painted tube shields reduces
>>> the heat in the tube by 17%, so yes, it does do something worthwhile. For
>>> instance, reducing the heat of 300 degrees to 249 degrees, or -51 degrees.
>>> 
>>> You may not think this is worthwhile, but I do.
>>> 
>>> According to my reading on the subject, reducing tube heat by even 1 degree
>>> contributes significantly to longer tube life.
>>> 
>>>> Better to leave the tubes uncovered and use the fan.
>>> True.
>>> 
>>> Ken W7EKB
>>> ______________________________________________________________
>>> Hammarlund mailing list
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>>> Help: http://mailman.qth.net/mmfaq.htm
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>>> ** For Assistance: dfischer at usol.com **
>>> 
>>> 
>>> This list hosted by: http://www.qsl.net
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>> 
>> 
>> 
>> ------------------------------
>> 
>> Message: 6
>> Date: Sat, 4 Oct 2014 20:36:48 -0400
>> From: Bob Camp <kb8tq at n1k.org>
>> To: Hammarlund QTH LIST <hammarlund at mailman.qth.net>
>> Subject: Re: [Hammarlund] Tube shields and heat
>> Message-ID: <D2BD3C93-F767-4EAD-8166-59791378F888 at n1k.org>
>> Content-Type: text/plain; charset=windows-1252
>> 
>> Hi
>> 
>> Chemical rate law phenomenon are one of many things that cause degradation in a device. The rate law is true once you reach an activation energy level. For many of the materials in a tube that occurs in the > 1,000 C range. Yes a lot depends on exactly which reaction you are tracking on each material.
>> 
>> Cooling the outside of the tube does little for things like the filament. It?s going to be at ?glow? temperature regardless of what you do on the outer envelope. The grid to cathode spacing for a tube to work is such that the control grid will pretty much follow the cathode, regardless of what you do to the plate. The only thing you may be cooling with a black shield is the plate and to a lesser degree the suppressor grid (if it?s a pentode).  I have never seen a tube fail for glass envelope degradation due to temperature. Dropping them does not count in this case. Doubling the life of the glass envelope, when it never falls regardless does little to ?improve? the tube. Glass to metal seal temperates are a different issue, they are little impacted by a tube shield.
>> 
>> Since you depend on heat to activate the getter material, and it?s on the tube shell, cooling the shell may actually degrade the reliability if it?s taken to far.
>> 
>> ???????????????
>> 
>> Why do most tubes fail?
>> 
>> 1) The filament / cathode system runs out of coating / electron radiation capability. It stops glowing, at least in terms of electrons.
>> 
>> 2) The envelope fills with gas, but that does not poison the filament. This happens when a glass to metal seal fails.
>> 
>> 3) A weld breaks and the tube just goes dead. Normally this is due to cycling the tube. Welds are a ?high activation energy? item.
>> 
>> 4) A grid slumps and it shorts to another element in the tube
>> 
>> At least of the few 10?s of thousands of tubes I?ve seen, number one wins out by far. That one is not impacted by cooling at all. Numbers 2 and 3 depend a lot on what sort of tube it is. They happen more often than number 4 by far. I have yet to see a receiving tube with a hole burned in the plate. Maybe it happens, if it does, it?s rare (so it?s not on the list).
>> 
>> Cooling the tube isn?t going to impact 1 or 2 (the big ones) at all. It may impact 3 depending on the location of the weld. It certainly would impact 4 on the suppressor (but not the cathode or control grid). Holes burning in the plate are the big one that cooling would help. Since you aren?t addressing the main wear out mechanisms, cooling isn?t worth it.
>> 
>> Bob
>> 
>> On Oct 4, 2014, at 8:00 PM, Robert Moses <rhmoses at earthlink.net> wrote:
>> 
>>> The rate at which chemical reactions such as those involved in the
>>> degradation of tubes takes place increases 2.3 times for each 10 degree
>>> C increase in temperature. Cooler is always better as long as it is warm
>>> enough to work.
>>> 
>>> On 09/27/2014 12:54 PM, Kenneth G. Gordon wrote:
>>>> On 27 Sep 2014 at 13:31, Guido Santacana wrote:
>>>> 
>>>>> As for tube shields, if they are not IERC shields, paint will not do much.
>>>> Guido: on the basis of experiment, FLAT black painted tube shields reduces
>>>> the heat in the tube by 17%, so yes, it does do something worthwhile. For
>>>> instance, reducing the heat of 300 degrees to 249 degrees, or -51 degrees.
>>>> 
>>>> You may not think this is worthwhile, but I do.
>>>> 
>>>> According to my reading on the subject, reducing tube heat by even 1 degree
>>>> contributes significantly to longer tube life.
>>>> 
>>>>> Better to leave the tubes uncovered and use the fan.
>>>> True.
>>>> 
>>>> Ken W7EKB
>>>> ______________________________________________________________
>>>> Hammarlund mailing list
>>>> Home: http://mailman.qth.net/mailman/listinfo/hammarlund
>>>> Help: http://mailman.qth.net/mmfaq.htm
>>>> Post: mailto:Hammarlund at mailman.qth.net
>>>> 
>>>> List Administrator: Duane Fischer, W8DBF
>>>> ** For Assistance: dfischer at usol.com **
>>>> 
>>>> 
>>>> This list hosted by: http://www.qsl.net
>>>> Please help support this email list: http://www.qsl.net/donate.html
>>>> 
>>> 
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>> 
>> 
>> ------------------------------
>> 
>> Subject: Digest Footer
>> 
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>> ------------------------------
>> 
>> End of Hammarlund Digest, Vol 129, Issue 7
>> ******************************************
> 
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