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Magnum S-9 Upgrade?

ctvanover

ctvanover

N/A
May 22, 2005
161
7
28
61
Archdale, NC 27263
Has anyone tried the SX-175 Black Magnum Power Cabinets for the Magnum S-9's? Or can you just take a 2 pill and put it inside of a Magnum S-9? What would be the consequences? Would it help it or hurt it?

Included Parts:
Aluminum Top Cabinet and Bottom Cabinet/Heatsink
175+ Watt Final Amplifier - Low Pass Filter - Directional Coupler Circuit Board Assembly
Heavy-Duty Aluminum Mounting Bracket
Heavy-Duty, 12 Gauge, 10 Foot Power Cord Assembly with 30A Inline Fuse
 

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Sam Lewis of RF International tells me they sell a lot of these cabs. They make them for the S-9 and other large cabinet radios. They use four ERF-2030 MOSFET transistors. They also are going to make a 300 watt version cabinet - using four of the ERF-7530 MOSFET.

Never reviewed either one . . .
 
I've seen the video and it was quite impressive, but I want to know more about upgrading the S-9. Which one the SX175 cabinet or the 2 pills and the effect it would have on my radio?
 
ctvanover said:
I've seen the video and it was quite impressive, but I want to know more about upgrading the S-9. Which one the SX175 cabinet or the 2 pills and the effect it would have on my radio?
Click to expand...

What kind of pills? You didn't say. There are 1446's, 2290's, and 2879's - as well as others. They are all capable of putting out different power depending on how the amp has 'biased' these transistors. Some work better on SSB than AM. Biasing will also dictate how well they perform on AM as opposed to SSB.

'Pills' are 'bipolar' devices - while MOSFETS are a different design still. These power cabinets use the MOSFET type of device - and work the same in either AM or SSB mode. Biasing doesn't change their operation like the bipolars will. At least; that is what I've been told anyway. Some people don't like the sound difference that MOSFETS have - compared to the sound of 'pills'.

I suppose it is up to you, as to preference. You were talking about the cabinets. The new cabinet that has the four ERF-7530's will be conservatively rated at 300 watts - but can do more. I wouldn't push them to their breaking point; but they can go beyond.

If you wanted to save money; I would go with a 2 pill amp that can do 250 watts and cost you around $120. 1446's if you mostly do SSB; 2290's if you use AM more. The cabinet amps may cost more; but give the convenience of keeping it all under the radio's hood.

Depends what you need and what your budget is - IMO . . .
 
mosfets have a certain amount of voltage/bias required to turn them on so they are not actuated by rf voltage so if they sound crap on ssb they sound crap on AM.
 
I just didn't know, that's why I asked! I'll probably go with the SX175 power cabinet from magnum. Maybe even wait for the 300+ cabinet and see what happens. I have a Texas Star DX-350 that I was planning on using in my pickup with an S-9 but I was also planning on putting an S-9 into a Peterbilt tractor but just didn't want the extra hassle of the TS DX-350. Plus the guy that owns the truck probably wouldn't let me anyway.

Thanks for any and all help. Hope everyone here has a safe and happy New Year!
Chris
 
I suppose you must be aware that these power cabinets aren't a 'plug and play' thing. They will require decent soldering skills and some time and patience - not to mention removing some radio parts. I would have a shop do it if you aren't familiar with the components or don't feel up to it.

A S-9 comes in two versions: either it has dual MOSFET/ERF-2030 finals or dual bipolar/2SC1969 finals. The MOSFET powered radio will have ~65 watt output and the bipolar powered radio with have about ~35 watts output.

A Texas Star 350 amp requires no more than 25 watts to drive it; 20 watts is optimal.

If you use too much power into the amp from the radio - it will distort your transmitted signal 'significantly'. If you have the MOSFET version of this radio; you might have to adjust the output of the radio internally to get it to put out less power to stay within the input parameters of the TS 350 for optimal performance.

The TS350 uses two 2SC2879's 'pill' type bipolar transistors.

Just some things to consider . . .
 
mackmobile43 said:
mosfets have a certain amount of voltage/bias required to turn them on so they are not actuated by rf voltage so if they sound crap on ssb they sound crap on AM.
Click to expand...

while one may exist somewhere, i have yet to see a mosfet final export radio-factory or user modified-actually operate as intended. SSB exports using mosfets are a dead giveaway if you listen carefully on a quality receiver. some are so bad you don't even need a quality receiver. AM covers up many of the imperfections, but if you know what you're listening for, you can tell again. i had this discussion with a certain magnum repair center operator about 2 weeks after the first mosfet 257's hit the streets. he knew exactly what i was talking about when i complained about the warbly SSB audio. there was/is a fix, but it is just a bandaid for the fact that the whole transmit section was NOT designed around mosfets. true, you can replace a bipolar transistor with a mosfet and a couple of additional parts, but you still do not have a real mosfet transmitter section.

while robb is pretty much correct, i would go so far as to say forget the add on magnum amp and go with a dx500. yeah, bigger then your original plans, but far easier to match to the dual final S9 then the dx350 will be. on AM you'll have nearly 100 watts of carrier, and your 'swing' will be better then 400 watts. twice as much cost as the sx175, but nowhere near the hassle.
 

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