[Amps] Alpha 87A

John Lyles jtml at losalamos.com
Sat Mar 30 20:23:52 EDT 2013 

Running the tubes with only filament on for at least 30 minutes before
applying HV is a good practice. Longer is certainly more conservative
but more than 24 hours is not needed. After a few hours they should take 
HV fine if they have good vacuum, but reduce the HV if you can and 
slowly bring them up to full voltage, no plate current at this time. If 
Alpha doesn't allow reduction of voltage, even CW mode, then don't worry 
about it, but keep bias up so that no plate current is drawn. Like in 
cutoff if you can, as in class C - CW mode. If they hold for 10 minutes 
of HV or so, they are likely going to be fine. When you start 
dissipating power in the plate in linear operation, some heating occurs 
which will drive out occluded gas from the materials. You might get a 
flash, and that is where your series resistor to the plate supply helps 
out by limiting current in the arc.

In bigger tubes (triodes and tetrodes) that require a crane to install, 
I do this very practice and have had few arcs or gas bursts in many 
tubes. We bring up the RF power very carefully while watching for arcs 
or gas bursts on tubes with ion pumps mounted on them. Modern pyrolytic 
graphite grid tubes have very little activity if any at all, as they are 
processed at higher temperatures at the factory than wire grids. The 
addition of an active crowbar circuit that will prevent a 30 AWG wire of 
20-30 cm length from vaporizing, when shorted across the power supply, 
is insurance that we won't ruin a tube in a self arc.

I think you will be fine just being cautious and lighting up the 
filaments overnight first.
73
John
K5PRO


> Message: 3
> Date: Fri, 29 Mar 2013 11:12:51 -0400
> From: john starr001 <jstarr001 at hotmail.com>
> To: "amps at contesting.com" <amps at contesting.com>
> Subject: [Amps] Alpha 87A - Gettering NOS 3CX800A7's
> Message-ID: <BLU170-W32A47AE98BB8D553565359F2D30 at phx.gbl>
> Content-Type: text/plain; charset="iso-8859-1"
>
>
>
> I have an Alpha 87a and would like to replace with 20 year old NOS 3CX800A7 pair.  These have never been used.  I would like to getter the tubes by running them for 1-2 days but I have no setup other than the 87A.  I believe the 87A applies HV and screen voltage after a 3 minute timer period.   As long as I dont apply any RF signal, would it be harmful to the tubes to insert them into the 87A and let them cook for a day or so with HV applied?
>
> thanks
>
> john
>   		 	   		   		 	   		
>
> ------------------------------
>
> Message: 4
> Date: Fri, 29 Mar 2013 21:25:28 +0000
> From: "John Simmons" <jasimmons at pinewooddata.com>
> To: amps at contesting.com
> Subject: [Amps] Henry 2K-2 multimeter
> Message-ID: <emf1be8626-f603-4a6f-9e6e-84113a2464dd at john-pc>
> Content-Type: text/plain; format=flowed; charset=utf-8
>
> Does anyone know the coil resistance of this meter? I have to replace
> one with an open coil.
>
> 73, John NI0K
>
> ------------------------------
>
> Message: 5
> Date: Sat, 30 Mar 2013 09:16:24 -0400
> From: "Col. Paul E. Cater" <paulecater at gmail.com>
> To: Amps reflector <amps at contesting.com>
> Subject: [Amps] Molex Pins
> Message-ID:
> 	<CAJLRWYaOxWfvB=eK_vo8uCnHpO31rCQjKijQMNMt5aeJU8DP2g at mail.gmail.com>
> Content-Type: text/plain; charset=ISO-8859-1
>
> This is an obvious case of brain flatulence.  I have ordered 4 different
> part numbers from Mouser for the *pins* only that fit the power connectors
> on Icom and other rigs.  The standard 6 hole kind.  I still don't have the
> correct size.
>
> Anyone have a part number for these off the top of their head?  Male &
> female.
>
> Thanks,
> Paul
> WD8OSU
>
>
> ------------------------------
>
> Message: 6
> Date: Sat, 30 Mar 2013 14:33:01 +0000
> From: Rick Stealey <rstealey at hotmail.com>
> To: john starr001 <jstarr001 at hotmail.com>, "amps at contesting.com"
> 	<amps at contesting.com>
> Subject: Re: [Amps] Alpha 87A - Gettering NOS 3CX800A7's
> Message-ID: <COL124-W588644C35AEA60ABAEC35DCEDC0 at phx.gbl>
> Content-Type: text/plain; charset="iso-8859-1"
>
> If they need gettering, putting full HV on them will cause them to arc, by definition.
> Maybe you could put a large value resistor in the HV lead temporarily and see if they can take it.
>
> Rick  K2XT
>
>
>
>   		 	   		
>
> ------------------------------
>
> Message: 7
> Date: Sat, 30 Mar 2013 08:29:45 -0700
> From: "Jim W7RY" <w7ry at centurytel.net>
> To: "Col. Paul E. Cater" <paulecater at gmail.com>,	"Amps reflector"
> 	<amps at contesting.com>
> Subject: Re: [Amps] Molex Pins
> Message-ID: <91DE0592912C43359F808DA74B36B9C5 at JimsLaptop>
> Content-Type: text/plain; format=flowed; charset="iso-8859-1";
> 	reply-type=original
>
> Cant buy them from Mouser. I too went through the exercise. And most of the
> plugs/pins that you buy on the net, (quick silver, The RFC etc) the female
> pins are too big for the male pins of the radio.
>
> At The RFC, the pins the sell with the plugs that are a different
> configuration and wont plug into the radio, are fine.
> But the pins they ship with the plugs that do plug into the radio, are too
> big and fit very loosely.
>
> Good luck!
> 73
> Jim W7RY
>
>
> -----Original Message-----
> From: Col. Paul E. Cater
> Sent: Saturday, March 30, 2013 6:16 AM
> To: Amps reflector
> Subject: [Amps] Molex Pins
>
> This is an obvious case of brain flatulence.  I have ordered 4 different
> part numbers from Mouser for the *pins* only that fit the power connectors
> on Icom and other rigs.  The standard 6 hole kind.  I still don't have the
> correct size.
>
> Anyone have a part number for these off the top of their head?  Male &
> female.
>
> Thanks,
> Paul
> WD8OSU
> _______________________________________________
> Amps mailing list
> Amps at contesting.com
> http://lists.contesting.com/mailman/listinfo/amps
>
>
>
> ------------------------------
>
> Message: 8
> Date: Sat, 30 Mar 2013 08:34:02 -0700
> From: Bob K6UJ <k6uj at pacbell.net>
> To: Amps reflector <amps at contesting.com>
> Subject: Re: [Amps] Molex Pins
> Message-ID: <13270DF1-6564-46CD-94EE-5AF1A8673D1F at pacbell.net>
> Content-Type: text/plain; charset=us-ascii
>
> So our best bet is to order from Icom ?
>
> Bob
> K6UJ
>
>
> On Mar 30, 2013, at 8:29 AM, Jim W7RY wrote:
>
>> Cant buy them from Mouser. I too went through the exercise. And most of the plugs/pins that you buy on the net, (quick silver, The RFC etc) the female
>> pins are too big for the male pins of the radio.
>>
>> At The RFC, the pins the sell with the plugs that are a different configuration and wont plug into the radio, are fine.
>> But the pins they ship with the plugs that do plug into the radio, are too big and fit very loosely.
>>
>> Good luck!
>> 73
>> Jim W7RY
>>
>>
>> -----Original Message----- From: Col. Paul E. Cater
>> Sent: Saturday, March 30, 2013 6:16 AM
>> To: Amps reflector
>> Subject: [Amps] Molex Pins
>>
>> This is an obvious case of brain flatulence.  I have ordered 4 different
>> part numbers from Mouser for the *pins* only that fit the power connectors
>> on Icom and other rigs.  The standard 6 hole kind.  I still don't have the
>> correct size.
>>
>> Anyone have a part number for these off the top of their head?  Male &
>> female.
>>
>> Thanks,
>> Paul
>> WD8OSU
>> _______________________________________________
>> Amps mailing list
>> Amps at contesting.com
>> http://lists.contesting.com/mailman/listinfo/amps
>> _______________________________________________
>> Amps mailing list
>> Amps at contesting.com
>> http://lists.contesting.com/mailman/listinfo/amps
>
>
>
> ------------------------------
>
> Message: 9
> Date: Sat, 30 Mar 2013 09:36:09 -0600
> From: "Fern" <crc at cyberlink.bc.ca>
> To: <amps at contesting.com>
> Subject: Re: [Amps] Alpha 87A - Gettering NOS 3CX800A7's
> Message-ID: <669B45AC61F54B58B21193B5DE655867 at your03667082de>
> Content-Type: text/plain;	charset="iso-8859-1"
>
> Just don't connect the plate caps while doing this gettering.   Fern
>
> ----- Original Message -----
> From: "Rick Stealey" <rstealey at hotmail.com>
> To: "john starr001" <jstarr001 at hotmail.com>; <amps at contesting.com>
> Sent: Saturday, March 30, 2013 8:33 AM
> Subject: Re: [Amps] Alpha 87A - Gettering NOS 3CX800A7's
>
>
>> If they need gettering, putting full HV on them will cause them to arc, by definition.
>> Maybe you could put a large value resistor in the HV lead temporarily and see if they can take it.
>>
>> Rick  K2XT
>>
>>
>>
>>
>> _______________________________________________
>>
>
> ------------------------------
>
> Subject: Digest Footer
>
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> Amps mailing list
> Amps at contesting.com
> http://lists.contesting.com/mailman/listinfo/amps
>
>
> ------------------------------
>
> End of Amps Digest, Vol 123, Issue 58
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>

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