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@hotmail.com>
To: "amps@contesting.com" <amps@contesting.com>
Subject: [Amps] Alpha 87A - Gettering NOS 3CX800A7's
Message-ID: <BLU170-W32A47AE98BB8D553565359F2D30@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@pinewooddata.com>
To: amps@contesting.com
Subject: [Amps] Henry 2K-2 multimeter
Message-ID: <emf1be8626-f603-4a6f-9e6e-84113a2464dd@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@gmail.com>
To: Amps reflector <amps@contesting.com>
Subject: [Amps] Molex Pins
Message-ID:
<CAJLRWYaOxWfvB=eK_vo8uCnHpO31rCQjKijQMNMt5aeJU8DP2g@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@hotmail.com>
To: john starr001 <jstarr001@hotmail.com>, "amps@contesting.com"
<amps@contesting.com>
Subject: Re: [Amps] Alpha 87A - Gettering NOS 3CX800A7's
Message-ID: <COL124-W588644C35AEA60ABAEC35DCEDC0@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@centurytel.net>
To: "Col. Paul E. Cater" <paulecater@gmail.com>, "Amps reflector"
<amps@contesting.com>
Subject: Re: [Amps] Molex Pins
Message-ID: <91DE0592912C43359F808DA74B36B9C5@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@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
------------------------------
Message: 8
Date: Sat, 30 Mar 2013 08:34:02 -0700
From: Bob K6UJ <k6uj@pacbell.net>
To: Amps reflector <amps@contesting.com>
Subject: Re: [Amps] Molex Pins
Message-ID: <13270DF1-6564-46CD-94EE-5AF1A8673D1F@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@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
------------------------------
Message: 9
Date: Sat, 30 Mar 2013 09:36:09 -0600
From: "Fern" <crc@cyberlink.bc.ca>
To: <amps@contesting.com>
Subject: Re: [Amps] Alpha 87A - Gettering NOS 3CX800A7's
Message-ID: <669B45AC61F54B58B21193B5DE655867@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@hotmail.com>
To: "john starr001" <jstarr001@hotmail.com>; <amps@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
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
------------------------------
End of Amps Digest, Vol 123, Issue 58
*************************************
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|