I’m looking for anyone’s experience in successfully soldering an anode high voltage cap-contact on a final tube. ?Particularly, being that the typical maximum bulb temperature of the tube is 500 degrees F, most commonly available modern solder alloys have a melting temperature around 430 degrees F, that is the non-leaded alloys; I expect adding lead would decrease the melting temperature further. ?Industry defines a 96.5% Sn - 3% Ag - ?0.5 % Cu alloy as “High Temperature Solder.” ?With the anode in direct contact with the bulb sitting centrally just above the heater, and heat rising, I would expect this solder would melt during normal operation due to the heat being constantly added. ?The tube manufacturers used some kind of solder to electrically bond the anode wire that penetrates the glass bulb to the HV cap-contact: what alloy, I know not. ?What has been your experience in re-soldering the anode HV contact on these final tubes? ?Successful to date?

?

Thank you.

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73, Michael Smith, N4KZO

On Jan 30, 2025, at 4:54?PM, Leland L. Bahr via groups.io <w5drc@...> wrote:

First off, I glue the cap back on the tube with Muffler Cement sold in a toothpaste tube at a local Auto parts store.? Then I use normal electrical solder.? I have never had my re-soldering on a tube melt.

Lee, w0vt

On 1/30/2025 3:48 PM, Michael Smith via groups.io wrote:

I’m looking for anyone’s experience in successfully soldering an anode high voltage cap-contact on a final tube. ?Particularly, being that the typical maximum bulb temperature of the tube is 500 degrees F, most commonly available modern solder alloys have a melting temperature around 430 degrees F, that is the non-leaded alloys; I expect adding lead would decrease the melting temperature further. ?Industry defines a 96.5% Sn - 3% Ag - ?0.5 % Cu alloy as “High Temperature Solder.” ?With the anode in direct contact with the bulb sitting centrally just above the heater, and heat rising, I would expect this solder would melt during normal operation due to the heat being constantly added. ?The tube manufacturers used some kind of solder to electrically bond the anode wire that penetrates the glass bulb to the HV cap-contact: what alloy, I know not. ?What has been your experience in re-soldering the anode HV contact on these final tubes? ?Successful to date?

?

Thank you.

?

73, Michael Smith, N4KZO

Similar to Lee, but I just use my normal solder. ?

Never had an issue after but… I never had a tube that hot (I guess).

? ? ?Frank Krozel

? ? ? ? ? ?KG9H

Life Member, ARRL

? ? (630) 924-1600

kg9hfrank@...

On Jan 30, 2025, at 4:54?PM, Leland L. Bahr via groups.io <w5drc@...> wrote:

First off, I glue the cap back on the tube with Muffler Cement sold in a toothpaste tube at a local Auto parts store.? Then I use normal electrical solder.? I have never had my re-soldering on a tube melt.

Lee, w0vt

On 1/30/2025 3:48 PM, Michael Smith via groups.io wrote:

I’m looking for anyone’s experience in successfully soldering an anode high voltage cap-contact on a final tube. ?Particularly, being that the typical maximum bulb temperature of the tube is 500 degrees F, most commonly available modern solder alloys have a melting temperature around 430 degrees F, that is the non-leaded alloys; I expect adding lead would decrease the melting temperature further. ?Industry defines a 96.5% Sn - 3% Ag - ?0.5 % Cu alloy as “High Temperature Solder.” ?With the anode in direct contact with the bulb sitting centrally just above the heater, and heat rising, I would expect this solder would melt during normal operation due to the heat being constantly added. ?The tube manufacturers used some kind of solder to electrically bond the anode wire that penetrates the glass bulb to the HV cap-contact: what alloy, I know not. ?What has been your experience in re-soldering the anode HV contact on these final tubes? ?Successful to date?

?

Thank you.

?

73, Michael Smith, N4KZO

I have used something like cast iron stove cement and pretty sure I used regular solder..?? It worked on a 6146 I recall.

?

John K5MO