Storage Issues with 5894 Tubes

[WA1RNE]

 I have the Hallicrafters HA-6 and HA2 transverters and found that after pulling them out of storage, each 5894 had developed cracks at the base of the tube.

 One tube had a crack running from the base to about 1/3 the way up the glass envelope.

 Anyone ever experienced this with 5894's?  The transverters are likely 40-50 years old and had the original Hallicrafters labeled tubes - which ~19 years ago were still operational.

[WB2WIK]

Sounds like they took a mechanical hit (shock).

I've had 5894s "stored" for 40+ years that were perfect when put into service...but they weren't stored in sockets, they were in cartons.

[KB1GMX]

I've not seen that.  It suggests the unit was pranged in storage.

The two I have are still solid as when I got them maybe 4 decades ago.


Allison

[WA1RNE]

 Thanks Steve / Allison for responding.  Shock was the only thing that I could come up with as well.

After thinking about it, the HA-2 did take a hit at the power switch. It's been years but I recall jamming the switch knob against a shelf while moving it. Still not the kind of hit I would expect to cause a 2 1/2" diameter tube to crack, but that can be deceiving.

The HA-6 is a complete mystery. It was in an enclosed plastic storage tub and isolated from other gear for years.

Too bad, I wanted to keep those Hallicrafters tubes going as long as I could for old times sake.

The good news is, the first tube I picked up on eBay for $7.95 plus shipping provides around 65 watts output on CW which is about what it should be. I grabbed a second tube for $20 but haven't tested it yet, a Sylvania with hardly any wear marks on the pins. It's a crap shoot but guess I was feeling lucky.

[W8JX]

My guess here is with tubes inserted in sockets it stressed the base of tube via pins being forced out and forcing base to crack over time. This stress with tempatures changes over years created enough stress to crack bases. Remove tubes when in storage.

[WA1RNE]

My guess here is with tubes inserted in sockets it stressed the base of tube via pins being forced out and forcing base to crack over time. This stress with tempatures changes over years created enough stress to crack bases. Remove tubes when in storage.

 I think it varies with tube construction and in my case, at least with the HA-2 - handling. 

 Case in point, back around 1993 I picked up a 32V3 that had been stored in an inactive hams basement for at least 15 years. From the day I took it over the glass covering the tuning dial was cracked as was the band scale drum.

 Since Day 1 and as of last week, the 4D32 Final has played without a hitch with 100 watts carrier output on all bands. (hope it stays that way)

 The construction differences between the 5894 and 4D32 are night and day.

.....WA1RNE