| Author |
Message |
    
Yote
New member
Username: Yote
Post Number: 2
Registered: 2-2004
| | Posted on Saturday, February 28, 2004 - 1:13 am: | 
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Are the 4cx250b tubes good tubes?And whatt are they rated at.Im also looking for a telestar magnum they were made in Peoria IL.I found one for $500.00 its a two tuber.But cant reach the guy.I had one before it would rock.Thank you for youre help. |
Bruce
Senior Member
Username: Bruce
Post Number: 1032
Registered: 9-2003
| | Posted on Saturday, February 28, 2004 - 3:42 pm: |
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4cx250 are old creamic tubes WORKHORSES on 6 and 2 meters. I my amps i ran 3 tubes parrall on 6 meters and 2 tubes in push pull on 2 meters. The the 6 meter amp ran about 800 cw out ( 1200 pep ssb ) and the 2 meter one was good for 700 out Cw and about 1000 pep ssb. They will have a lot of gain at cb if run grounded cathode .... on 6 and 2 meters a 5 watt radio drove them to almost full output. Mine were still going when i sold both amps after 4 years of constent use ..... need i say more. |
Tech833
Moderator
Username: Tech833
Post Number: 576
Registered: 8-2002
| | Posted on Wednesday, March 03, 2004 - 8:48 pm: |
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The 4CX250 is not just an old tube. They are still being made and used today. The tube is rated at 250 watts plate dissipation and good up to VHF. Safely, you can use a 4CX250 at 500 watts output each. However, the more power you squeeze from them, the shorter their lifespan will be.
Here's what 4 C X 250 means-
4= This means it is a tetrode
C= This means it is ceramic. A 4X250 has glass.
X= I don't remember
250= 250 watts plate dissipation. |
Bruce
Senior Member
Username: Bruce
Post Number: 1044
Registered: 9-2003
| | Posted on Thursday, March 04, 2004 - 5:40 am: |
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833 The 4X150 which is the daddy of the 4cx250 dates back to WW2. These ARE old tubes very good old tubes still made still used after almost 50 years. When i built my amps in 71 they were and still are one of the better tubes for the 50 -450 mhz range..... the only reason i sold mine was where i moved i hade no room to store 2 19 inch racked amps in a 4 foot rack. The early 70;s VHF ARRL handbooks had the amps i built 3 tubes on 6 meters and push-pull pair on 2 meters...... mine were used for MOONBOUNCE. |
Mr_rf
Intermediate Member
Username: Mr_rf
Post Number: 273
Registered: 12-2001
| | Posted on Thursday, March 04, 2004 - 11:40 am: |
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X = silver plating if I remember right
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Crafter
Advanced Member
Username: Crafter
Post Number: 952
Registered: 12-2002
| | Posted on Thursday, March 04, 2004 - 10:23 pm: |
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833 did you ever do AC in a mobile? Looking at a 4cx1500 3 tube box for mobile. |
Yote
New member
Username: Yote
Post Number: 3
Registered: 2-2004
| | Posted on Tuesday, March 09, 2004 - 12:18 am: |
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I would like to thank you all for your info on the 4cx250b's Im just trying to learn,you guys are a big help,Thank you!!Oh,Does anyone still make a 2 tuber base amp useing these tubes? |
Tech833
Moderator
Username: Tech833
Post Number: 582
Registered: 8-2002
| | Posted on Wednesday, March 10, 2004 - 9:10 pm: |
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I just finished doing AC mobile of sorts. 10 KW ea. radio and TV transmitters in aircraft.
I rarely do mobiles, I concentrate on 'base stations'.
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Yote
New member
Username: Yote
Post Number: 8
Registered: 2-2004
| | Posted on Thursday, March 11, 2004 - 12:11 am: |
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What would a base amp running 2 or 3 4cx250b's cost? |
Tech833
Moderator
Username: Tech833
Post Number: 593
Registered: 8-2002
| | Posted on Tuesday, March 16, 2004 - 1:56 pm: |
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Why would you want to use 2 or 3 4CX250's instead of one 4CX1000 or better yet, a 5CX1500? Small tube, lots of gain. |
Yote
Junior Member
Username: Yote
Post Number: 18
Registered: 2-2004
| | Posted on Wednesday, March 17, 2004 - 2:08 pm: |
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tech833,I use to run a 2 tuber,4cx250b's,I guess i liked that amp,What would you suggest,as far as a tube set up 1k plus swing,I wouldnt want to dead key 1k if it did i would want a low setting on it no receive amp,good swing.Im wanting to get away from sweep tubes and go back to the ceramic less tubes do more and cheaper to replace.Also easier to get.Thank you for any advice,yote |
Tech833
Moderator
Username: Tech833
Post Number: 601
Registered: 8-2002
| | Posted on Friday, March 19, 2004 - 1:37 am: |
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I have an amp that uses a pair of 4-400 glass tubes that works on 160-10 meters. Running full legal output, I can easily run 125% positive peaks on AM on all bands (positive peak is what you are calling 'swing'). Unless you simply want an amplifier than has way more headroom than you will ever use (for longevity of the tube obviously), then running a ceramic 4CX1000 or perhaps a 5CX1500 would be your best bang for the buck. When you get into lerger tubes, cooling becomes a chore.
Remember, running class C, you can safely get carrier power double the plate dissipation factor. So, for a 4CX1000, you could safely get 2KW carrier, and 4KW positive peaks. If you only run the legal limit (which I am sure you will do) then you have 3dB of headroom. Your tube would last nearly a lifetime.
I have transmitters on the air with pairs of 4CX35000's and larger that run real nice. That is, if you need 100KW with 125% positive peak capability! Tube life is about 5 years of 24/7 use. |
LennyP (Unregistered Guest)
Unregistered guest
| | Posted on Friday, March 19, 2004 - 1:03 pm: |
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Does anyone have any repair info on the Yaesu FLDX2000 amplifier?
The tubes that are used in this amp is the 6KD6, the top of the tube is black indicating maybe tube is damaged. |
Yote
Junior Member
Username: Yote
Post Number: 24
Registered: 2-2004
| | Posted on Friday, March 19, 2004 - 1:34 pm: |
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wow you talk about info.There is no way I would want to go over 2k.I like the people down the road.Dont want them mad.Lets say,500-1500 watts max with the low side being 500 or even less.Watt would you say would be the best way to go for the money?And were would i be able to get it??My old phantom i love it but I need to retube it and clean it again,it shure picks up the dust.Thank you very much for your time!!!I hope I can meet you someday,Take care-Yote |
