Discussion in 'Amateur Radio Amplifiers' started by WA6MHZ, May 26, 2012.
Be careful around that Beryllium heatsink.
Good to hear you have it working Pat.
I second the idea of leaving the amplifier stock.
Don't operate the amplifier without the fuse, the 8873 has a VERY sensitive grid and the fuse is the only protection.I limit the grid current to 8-10mA and get about 450 out. It's also a good idea to rig up a small fan for the heatsink, it can get VERY hot.If I remember correctly, Heath indicated a maximum temperature of up to 750F!Good luck---
Hi If you looking for a Brand NEW 8873 tube i may sell my spare , ZL2WL
It doesn't have a Beryllium heatsink.
It has an aluminum heatsink with a Beryllium-Oxide thermal link which is fired and polished and you could rest it on your tongue with no danger.
The powder created by machining or filing it is dangerous if breathed in. It would be silly to do that, since the original link is just the right size and there's no need to machine or file it. The BeO thermal link came from Eimac and is a "consumer" product with no special warnings other than not to machine, saw or file it.
Got it, Been a while since ive seen the inside of one of those. I could not remember how the Beryllium played in that amp exactly i just new that it was in there and dangerous if altered.
I will get the proper fuse and install it. Also will rig up some sort of fan, as fan noise is not an issue. The whole point of the SB-230 was to be dead quiet, but in my shack with 3 computers and other things running, who gives a Rats Hindquarters if there is a little muffin fan running? I could never hear the fan on the SB-200 or the Drake L7 either with all the OTHER noise!
I might be interested in that spare 8873 but shipping from ZL would be most expensive. What are U looking to see from it? I have never seen one at a swapmeet, and asked around Dayton from vendors selling tubes, but none had any or ever heard of any.
Uh oh! What the proper value is could be debated a lot, as it has been in another thread...
I missed that thread. Right now, I have a single strand from a #28 gauge wire across the fuse. Have no idea how much current that will take, but I would guess over an amp. Heathkit calls out for 3/4 amp (don't know if it is fast or slowblow
Fast blow,I use 1/2 amp in mine and pop one now and then, I just keep a spare taped to the back of the amp.