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Author Topic: If two 3-500zs are good in a SB-220, six must be better!  (Read 4143 times)
W7VO
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« on: October 27, 2011, 04:15:59 PM »

Gee, I wonder where the bandswitch went?

http://r.ebay.com/hokfuE

73;

Mike, W7VO
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KA5N
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« Reply #1 on: October 27, 2011, 05:57:51 PM »

Boy oh boy a CB special modded SB 220 .  I wouldn't touch it with a fork except for the
parts.  Notice the seller says it is for 10 meters only.  (well maybe a few meters this way
or that).

Amp is beginning to look like the old dozen sweep tube amps of old except they be 30-500's.

oh well
Allen
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NO2A
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« Reply #2 on: October 27, 2011, 07:29:34 PM »

Talk about a complete waste of good 3-500z`s. That person should be shocked with their own amp for butchering an old `220.    Wink
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W8JX
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« Reply #3 on: October 27, 2011, 07:46:57 PM »

How about the amp needed to drive this amp?
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K8AXW
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« Reply #4 on: October 28, 2011, 08:34:50 AM »

3Kv - 8Kw - Can't run it on 120VAC !
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AG6K
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« Reply #5 on: November 01, 2011, 09:40:26 AM »

Quote
8AXW
Allen
RE: If two 3-500zs are good in a SB-220, six must be better!
« Reply #4 on: October 28, 2011, 08:34:50 AM »
   
Reply with quoteQuote
3Kv - 8Kw - Can't run it on 120VAC !

  Allen == it might do semi-OK on a 50A 120v circuit if the HV-PS has a resonant-L filter and it's driven with at least 400w.   
Rich, ag6k
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K8AXW
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« Reply #6 on: November 01, 2011, 09:59:36 AM »

Quote
Allen == it might do semi-OK on a 50A 120v circuit if the HV-PS has a resonant-L filter and it's driven with at least 400w.   
Rich, ag6k


Rich:  I emailed the eBay seller for more info.  The 8,000 watts and 3,000V was his response.  Subsequent inquiry about the total plate current went unanswered.  However, if two 3-500Zs will pull say 0.750A, then six of them would pull at least 2.25A!  Unbelievable!

What I find unbelievable is that some of these guys will spend all of that time, energy and money to build something like this instead of just getting a ham ticket and running the legal limit with which they can work the world!  I suspect the wiring in their heads isn't as good as the wiring in these homebrew linears!

The 120VAC mains was my attempt at facetiousness.  Sorry.

Al
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AG6K
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« Reply #7 on: November 01, 2011, 11:11:47 AM »

Quote
K8AXW
Al
RE: If two 3-500zs are good in a SB-220, six must be better!
« Reply #6 on: Today at 09:59:36 AM »
   
Reply with quoteQuote
Quote
Allen == it might do semi-OK on a 50A 120v circuit if the HV-PS has a resonant-L filter and it's driven with at least 400w.   
Rich, ag6k


Rich:  I emailed the eBay seller for more info.  The 8,000 watts and 3,000V was his response


  A 3-500Z will do 1200w in at 3kV, so 6 of 'em should not even be able to do 8000w input - much less output.

.
Quote
Subsequent inquiry about the total plate current went unanswered.  However, if two 3-500Zs will pull say 0.750A, then six of them would pull at least 2.25A!  Unbelievable!

  the mfg spec is 0.4A max, so 6 of 'em should be able to do 2.4A

Quote
What I find unbelievable is that some of these guys will spend all of that time, energy and money to build something like this instead of just getting a ham ticket and running the legal limit with which they can work the world!
 

  Indeed Al.  It's especially puzzling since Amateur Radio licenses are presently so easy to obtain. .

Quote
I suspect the wiring in their heads isn't as good as the wiring in these homebrew linears!

The 120VAC mains was my attempt at facetiousness.  Sorry.

Al
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K0BT
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Posts: 176




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« Reply #8 on: November 06, 2011, 12:21:38 AM »

Here is a modified SB-221 in the Phoenix area, but it only has five 3-500z tubes for a claimed "4000 bird watts".  The guy must be selling it because he found out someone had one-upped him.

http://phoenix.craigslist.org/wvl/ele/2651777038.html

If five transistors is "five pills", then what do you call five 3-500zs?

Bob
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KA5ROW
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« Reply #9 on: November 06, 2011, 01:46:43 AM »

I think it could be a good buy 5 tubes @ $200 each = $1000. Heavy duty P/S, $1000, buy it, and make a real amp out of it. A 3 tube 3-500z with a tank for 10-160M   
What you get is a full legal output amplifier and 2 spare tubes.
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KC2RLY
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« Reply #10 on: November 07, 2011, 07:40:33 AM »



If five transistors is "five pills", then what do you call five 3-500zs?

Bob

scary
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KA5ROW
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« Reply #11 on: November 07, 2011, 06:06:54 PM »

Not having to use any external heat for the shack. You may even need to crack the windows some if it is 40+ outside.
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WA8UEG
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« Reply #12 on: November 10, 2011, 07:57:12 AM »

What a deal, sold for only $2,550.00. Once again I missed out on a great deal! Roll Eyes
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W8JI
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« Reply #13 on: November 10, 2011, 09:11:30 AM »

I think it could be a good buy 5 tubes @ $200 each = $1000. Heavy duty P/S, $1000, buy it, and make a real amp out of it. A 3 tube 3-500z with a tank for 10-160M   
What you get is a full legal output amplifier and 2 spare tubes.


I'm sure the tubes, after CB use, are in great shape.
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K1ZJH
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Posts: 898




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« Reply #14 on: November 10, 2011, 09:19:06 AM »

That would make a fine "VooDoo" restoration project for your website, Tom  Grin

LOL!

Pete
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