Tube Amp for 11 meters

[Master Chief]

Between the Heathkit SB-220, the Pride DX300 and the Dentron MLA 2500B which of these 3 linears would develop more output if used on AM (11 meters)? Which of these linears can be driven with 100 > 150 watts ? I've read about SB-220's that had 4 tubes. Is that the normal configuration, 4 tube sockets in the SB-220 ? Does the Pride DX300 and Dentron MLA 2500B also have multiple tube sockets ? I'm looking to upgrade to a non sweeptube linear and these are the three I'm looking at.

SB-220: 2 X 3-500Z tubes. This amplifier was designed for SSB use and therefore 33% duty cycle. The power supply is not big enough to give full output on AM. Drive for this amp is in the order of 100 watts. If you run it in AM and you want it to last, you need to run it on LOW/TUNE. Others run the snot out of it and it works, but will eventually destroy the amp. Nomad Radio has a few circuit modifications to change the bias for AM operation. There were mods to add more tubes to this amp and they are foolish. I'm a one tube man; if a single tube does not give you the desired output, get a bigger tube. This amp is the exception and a pair of 3-500ZG tubes works great! Just remember that the power supply was not designed for full output on AM!

Dentron MLA 2500B:This amp uses a pair of ceramic tubes that are no longer made. There is a modification to change this amp over to use a pair of 3CX800A7 tubes from Svetlana.

http://support2.overkalix.se/~sm2yer/shack/amp_mla2500/convert_3cx400a.pdf
http://dk9ip.ba-karlsruhe.de/pdf/mla2500/

This is your best bang for the buck using ceramic tubes. A pair of 4CX250B will NOT give you 2400 watts and is a foolish mod for this amp!

Pride DX-300/KW-1There are TWO versions of this amp, both using a single 4CX250B tube. This is my all time favorite CB amp! The KW-1 will take 100 watts drive but is not recommended. The DX-300 is a low drive amp. I keyed mine with 2 watts from a Cobra 2000 and it sounded great doing about 350 to 500 peak! Actually, you couldn't "hear" it, you just saw an increase in signal. I ran it on low only! On HIGH it would put out 900 watts peak and sounded like CRAP! I NEVER ran it on HIGH! Nomad Radio has a number of modifications for this amp and it is the driver of choice for many of the BOWL BUDDIES.

Sweep tube amps are sweep tube amps. What I was trying to say in my last post is that it is a waste of time to convert a sweep tube amp to a ceramic tube amp. If you want to run a sweep tube amp, convert it to run the 509 tubes because they are cheap and plentiful.

You need to ask yourself, what kind of power output do you want and how full is your checking account!

 

[SmackDown]

okay, since my concern at this time is AM operation I think I'm reading that I maybe should get the newer Phantom 500 with three settings and have someone convert the tubes to the 509/519 series ???? I guess I can drive that with a 50 watt modulator. The Dentron MLA2500B is a hard to impossible find. There is a Dentron clippertron on ebay but it hasn't been mentioned at all in any of the responses. There is an SB-220 and a Pride DX300 without the kw-1 suffix. I'm trying to maximize what I can do with my available greenstamps.


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[lords]

SmackDown, if you do decide to go with the SB-220 on 11 meters you won't be unhappy. I'm very satisfied with the performance of my SB-220 on both AM and SB.

I second that statement i am very happy and i even keep the load backed down some

 

[Unit 194]

SmackDown, if you do decide to go with the SB-220 on 11 meters you won't be unhappy. I'm very satisfied with the performance of my SB-220 on both AM and SB.

I second that statement i am very happy and i even keep the load backed down some

I hear ya! Loud and Clear!

 

[SmackDown]

okay the 509/519 series tubes ( 6KG6 ) are cheap @ $30.00 for 4 (average) :shock: , but is it a direct replacement ? Are there other adjustments that need to be made ? Bias ? Circuitry ?



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[DTB Radio]

For the 1KW+ range, I like the BlackCat JB2000 running off of 220V.

 

[SmackDown]

okay what changes need be made to change from 6LQ6 to EL509/519 ??? I read the pins will stretch the socket receptors then I read that maybe changing the sockets altogether is good because of higher heat. Are there circuit changes that need to be made also ? Is anyone here aware of the changes and care to share. I have the triple stage Phantom, older type with the keying tube.


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[SmackDown]

okay linearone I know you're joking but I'll bite...a modulator is something like the black cat JB 12 or the Maco Brute II

 

[Master Chief]

A modulator is completely different than a linear. You usually find them in broadcast transmitters.

I'll let QRN educate us.

 

[SmackDown]

I did some looking around since my last post and it seems the EL509/519 tube is as hard to find as 6LQ6's or 6MJ6's..anyone know of a russian source ???



73's

 

[dudmuck]

For the 1KW+ range, I like the BlackCat JB2000 running off of 220V.

its the magic of wood veneer.

 

[Captain Kilowatt]

A modulator is completely different than a linear. You usually find them in broadcast transmitters.

I'll let QRN educate us.

I'm not touching this one. I speak a differant language when it comes to amplifier output levels and exactly what modulators really are. :roll:

 

[SmackDown]

...in the case of the black cat JB-12 the output in watts is barely 100 but the modulation is over 100%... I recently saw a Maco Brute II advertised on craigslist. The seller claims it produced 200% modulation at 80>100 watts total.

I still need a source for EL509/519's without my having to lose a limb


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[AudioShockwav]

and exactly what modulators really are.

In the World of "I gotta have them Big Swing Watts""
CB Radio, a Modulator is a Amp with VERY NoN- Linear characteristics, with a very low dead key.

Roger?

73
Jeff

 

[SmackDown]

once I get some EL519's what's the next move(s) to make to completely convert from 6LQ6's ?
Where are the Techs :?


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