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Author Topic: Globe Champion 300  (Read 18737 times)
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Steve - K4HX
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« Reply #25 on: April 03, 2013, 12:23:16 PM »

Two were new and with very late date codes. One was used but worked FB. Some of the ones I've seen at the fest did appear to be well used.

The way I would approach the mod is to look for a 7094. If one is found in good condition for an reasonable price, go for it. Otherwise, I'd move on to the other options mentioned here. The good thing is that there are more than a few good options.




Condition and price?
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VE3AJM
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« Reply #26 on: April 04, 2013, 08:51:49 AM »

I managed to get some spares for use with my Viking I or 32V2, or finding a Globe Champ tx. That was back in the day when the 4D32 tube was extremely hard to find at a reasonable price, and I managed to find some new Cetron 7094s with a military sticker on the side of the tube box at a more reasonable price.

I always thought they were a cool tube, right from reading about their use in that 200 watt transmitter in the ARRL Handbook from the late 50s, after the run of the Chambers 813 transmitter in the Handbooks, and with Steves letter to ER magazine about using them in his Globe Champion.

Al VE3AJM

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KM1H
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« Reply #27 on: April 04, 2013, 03:51:17 PM »

The 7094 was RCA's attempt to update the 813 but it certainly was not very rugged in the few commercial products that used it. All the ones Ive seen the past few years at hamfests were in the $100 range for NIB and not much less for used ones which I didnt trust. At online tube bandits they are around $200 each....dont know how many sell at that price. The same sources have the 7854 at around $75, still not cheap.

In a Champ at half the voltage the 7094 sounds like a lifetime swap.
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w0vt
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« Reply #28 on: September 02, 2013, 10:43:09 PM »

I went on vacation this week and on the trip picked up a long wanted Globe Champion 300.  It is in the back seat of my car until I get back home to Texas in a week.  I have not opened it up yet but the prior owner has told me the final AX-9909 tubes are missing plus the 809 modulator tubes.  The rig has not been operational in over 25 years and it looks abused.  I know I am going to have to have a replacement dial cover for the VFO replaced as it is beyond use as it is so cloudy you can't read the vfo markings.  I sure hope the iron is OK.  I am suspecting the transmitter may have to be stripped and rebuilt from the ground up, but I sure hope that is not the case.  I got it FREE, so I can't complain and now have some wiggle room to invest money into the restoration.  This is not going to be some simple one week restoration project and not for the faint of heart!

As bad as the girl looks right now,  I'm excited about obtaining it and eventually getting it on the air again.  I think I have found a source for some 8643 tubes for a mod and I am hoping I can find some 809 modulator tubes.  (I don't know what is necessary to swap 809s for 811s bias wise.)

I see Motorola used the 8643 tubes and they tied the plates together with a round top heat sink anode connector with two holes drilled in it to accept the anode pins.  I'm thinking of finding some aluminum round bar stock and trying to make a couple anode connectors this way.  if anyone has some used Motorola ones for 8643,  I'd sure be interested in obtaining them from you.  I know the 5894 tubes had smaller diameter anode pins but maybe the spacing is the same and I could just drill those out bigger if ones for 5894 tubes were available.

Anyone have any 809s they could part with or know how to use 811s instead?

Lee, w0vt
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Steve - K4HX
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« Reply #29 on: September 02, 2013, 11:06:49 PM »

Just plug in the 811s and run them zero-bias. They do draw more filament current. If you are concerned, put in a separate fil tranny for the 811s.
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w0vt
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« Reply #30 on: September 02, 2013, 11:29:59 PM »

Thanks, Steve.  that is easy enough!

Lee, w0vt
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Tim WA1HnyLR
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« Reply #31 on: September 03, 2013, 11:32:53 AM »

Hi Tim,
Nobody mentioned the 4D32. I have a transmitter with a 4D32 in it( Viking 1-1/2) I am running 1000 volts on the tube. I am using a highly modified Globe King 500 modulator deck as the modulator. The 4D32 still has 150 watts outpoot after 11 years of service. About 40 years ago I worked on a Globe Chump. I put a 7094 in the PA. It worked very well,,,, When you could buy them over the counter. I have a Globe Chump that I have been planning on modifying for the last 25 years or so. The Tank circuit in the chump is rather light duty. It is comparable with something you would find in a DX 100 or other 100 watt transmitter. I would not trust it with anymore power than it already has to deal with. I have already stuffed a Globe King 500 mod transformer in to it. The 809s may give way to a pair of 811s., A push pull audio driver, and one 4D32.The Three diode ultra modulation circuit shall be employed. The modulation capabilities of the chump are on the edge. Years ago it was carrier power that sold transmitters. A carrier does not do the talking ,the modulator does. When it is said and done I will probably pass it along. I have enough 100-150 watt transmitters. In closing; if the Philament power switch on the gain pot is crapped out . Just remove it. Get the philament wiring away from the audio gain port to avoid the possibility of hum pick up.
Tim WA1HnyLR
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W2PFY
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« Reply #32 on: September 03, 2013, 01:06:24 PM »

Quote
philament


Any relation to the philamentdelpha orchestrator?
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The secrecy of my job prevents me from knowing what I am doing.
Tim WA1HnyLR
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« Reply #33 on: September 03, 2013, 02:15:49 PM »

Well, Philament is an elegant way of saying filament just as microphonium is for microphone, De Tim WA1HnyLR
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Steve - K4HX
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« Reply #34 on: September 03, 2013, 10:59:22 PM »

No, philodendron.



Quote
philament

Any relation to the philamentdelpha orchestrator?


* philodendron.jpg (38.2 KB, 375x349 - viewed 378 times.)
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w0vt
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« Reply #35 on: September 05, 2013, 12:06:50 PM »

Tim,
I am about to restore a 300 Champ too.  I'd be interested in getting a description of the cabinet paint job coloring and texture from you if your transmitter has an original cabinet finish on it.  I don't know much about Globe Champ finishes.  I can't tell or know if mine is original but I suspect it is not original.  It appears to be painted with a flat silver paint of some kind.  it is not a hammertone, sand or wrinkle finish.  There seems to be no BLUE or GREEN look to the silver.  How does this compare to yours?

Lee, w0vt
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w0vt
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« Reply #36 on: September 05, 2013, 12:23:05 PM »

I'd be interested in knowing from you experts if it would help to parallel or strap on some more capacitance to the oil filled filter cap in the high voltage power supply?  I think the oil cap is 6 uF if I recall correctly.  Seems kind of marginal to me.

Lee, w0vt
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