For whatever it is worth, I had this problem frequently in contest
service, even with the higher-capacity Harbach fan. Finally, I swapped
the filament springs for two from the grid, polished the tube pins and
the insides of the contacts, and have had no problems thereafter. I
could have done these things one at a time, but who believes in the
scientific method anyway?
73, Pete N4ZR
Check out the Reverse Beacon Network at
http://reversebeacon.net,
blog at reversebeacon.blogspot.com.
For spots, please go to your favorite
ARC V6 or VE7CC DX cluster node.
On 5/14/2014 9:55 AM, Carl wrote:
That Johnson 122-275 ceramic socket goes back to the 50's when just
about everything used expensive Eimac forced air flow cooling and the
cast aluminum sockets with chimneys cost more than the tubes. Johnson
received an OK from Eimac for horizontal cooling in their
4-250A/4-400A transmitters and amps and other companies followed suit.
The SB-220 cooling is well thought out and sufficient as designed. The
problem is builders and other owners who cannot read the manual and
dont place the fan blade at the proper point on the shaft and/or leave
off that small aluminum air deflector on top of the perforated cover.
Failure to clean the blades and lubricate the motor just adds another
level of problems.
The socket uses a rivet to assemble the pin and when the tube pin
overheats that compression bond is weakened. A cure is to gently
compress the pin to original spacing and then use a D-550 or similar
gun and a bit of diluted hydrocholric acid, also sold as plumbers
soldering fluid, and flow some silver bearing solder to bond it all
together. Use a toothbrush and the acid to remove the heat bluing.
Flush out the acid residue with a water and baking soda mix in a spray
bottle.
Others may be more comfortable replacing the socket (-;
I dont like the Chinese sockets as it is easy to rupture the tube seal
especially with the older all glass base without the brown compression
ring. Ive heard a few stories of that happening with both versions.
In the hundreds of 3-400/500 amps Ive worked on only a very small
number required replacing the socket which were broken by a users
brute force attempt to restore tension.
Carl
KM1H
----- Original Message ----- From: "Alf Pousar" <alf.pousar@surffi.net>
To: <Amps@contesting.com>
Sent: Wednesday, May 14, 2014 4:15 AM
Subject: [Amps] 3-500Z pin becomes unsoldered
If your solder lugs are dripping the solder due to heath, clean the
lug using a good desolder wick and wrap the wire around and trough
the lug. Then take some small wrapp wire and wrapp around the lug.
Then... solder with high temp ten/silver solder and the problem is gone.
Alf OH2QM
_______________________________________________
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
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|