Hello Kim, Congrats on having your dad's original Globe Champion. I've had Globe Champions for years (picture on QRZ) and tried lots of different tubes in them, mostly just for fun and experimentation.
The AX9909s are VERY fragile IMHO. A pentode, they remind me of a TV sweep tube. The only reason I would keep them is if you really wanted to try to keep the radio "original". In that case, I would be very careful to NEVER allow them to pull a lot of plate current, especially while tuning. Almost every one I've seen cracks or leaks at the plate pin on the bottom. You can hear the tubes making crackling noises as they heat and cool during normal operation. Not very comforting. :) The 4-65's I tried for finals seemed sluggish and not very efficient at 1000vdc. I think they want more voltage. I'd recommend 5894's or that heavy duty version that W5JO mentioned. They are not too hard to find. There were lots of them produced for business radios and repeaters. They plug in the original sockets but you may have to remove the socket sub-chassis and rewire the sockets. Not too difficult. Very important to remember the filament supply voltage is 12.6v and to wire the filaments as needed. The low voltage transformer is a weak point. If you use different finals, you can solid state the plate supply to remove some load from it. This will raise the plate voltage some and I wouldn't do that with 9909's. You can plug in 811A's for the 809 modulators and run 0 volts bias. That will eliminate the negative bias rectifier for the 809's and give you heftier, easy to find modulator tubes. I like 811A's for audio tubes. Good luck getting it back on the air and let us know if you run into any problems. 73', Kent/KA5MIR On Sunday 13 May 2007 04:44:52 pm Kim Elmore wrote: > If all goes well and I can get enough space cleared, I'm going to set > up my Dad's (W5JHJ) Globe Champion 350 and Hammarlund HQ-170A in my > shack, alongside my TenTec Orion II. It has the original AX9909 > finals and my Dad is the original owner (purchased in 1959!). I think > he even has a spare set of finals for it. Aside for some mods my Dad > has made over the years, it's original, as is the HQ-170A. The last > time we fired them up, everything worked and it all tuned as it > should have. This thing even has the 11 m band on the VFO scale > (which, as I recall, is terribly inaccurate), though none of the 11 m > components. > > I seldom see HQ-170As appear for sale and I can't think of the last > time I saw a Globe Champ 350 for sale, so I have no idea what its > value is; I'm guessing not much. Whatever it is, I assume it's higher > with the AX9909's. Still, I've also seen some ideas about replacing > the AX9909's with a pair of 4-65's. I can't however, find those posts > anymore. Since the AX9909's are made of unobtainium, if they quit and > the spares have a problem, I'll have to perform this mod. Are 4-65's > more common? And, does anyone know the details of that mod? If not > the 4-65, what would I use? > > Kim Elmore, N5OP ______________________________________________________________ AMRadio mailing list List Rules (must read!): http://w5ami.net/amradiofaq.html List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net To unsubscribe, send an email to [EMAIL PROTECTED] with the word unsubscribe in the message body.
