Is this a "Clean" amplifier?

[T23]

I wanted some opinions on this amplifier. What can I expect as far as it having a clean signal? I know it mostly depends on what is driving it...


T23

 

[TonyV225]

UUUUUM.... This is a internal amplifier of a radio???

 

[hookedon6]

UUUUUM.... This is a internal amplifier of a radio???

yes Galaxy DX 94 HP ,........... 4 irf520's mosfet

 

[Robb]

yes Galaxy DX 94 HP ,........... 4 irf520's mosfet

They used to have two 2290's in them.
When did they change?

 

[TonyV225]

Robb there all going to Mosfets. I see regular standard amplifiers are also starting to do this or experimenting with it.

 

[Robb]

Yep, just looked at the schematics for the radio and the PA sections. This radio uses two IRF-520's to drive four IRF-520's in the PA. The alignment specs say 100 watt output/SSB and 35 watts AM/carrier (think I would adjust the AM carrier to 25w though - to keep the IRF's running cooler and cleaner). Since it is a 10m radio; it also has to be type accepted - which it is. So I would say; yes - it is a clean amp. But this will depend upon mic modulation levels. Of course, more than 100% modulation/100% ALC is going to mess up the TX purity. So will driving the amp more than 100 watts . . .

 

[binrat]

I had a 94 for a few years. Good radio, just did a conversion and increased the mod alittle and it was solid 90ish watts. That extra 10 watts is not going to make a difference besides more heat from the PA section.

 

[WA2SI]

Since it is a 10m radio; it also has to be type accepted

I don't think type acceptance is required for amateur radio transceivers. It is for 11-meter/CB though.

73, Bert

Sent from my SCH-I535 using Tapatalk 2

 

[9C1Driver]

I wanted some opinions on this amplifier. What can I expect as far as it having a clean signal? I know it mostly depends on what is driving it...


T23

My first thought is your question is flawed, the galaxy DX94 is a Radio not an Amplifier. It is one of the higher powered Export radio's Galaxy makes. You have no control over what's "driving" it other then when the tech converts and tunes the radio.

 

[Robb]

I don't think type acceptance is required for amateur radio transceivers. It is for 11-meter/CB though.

73, Bert

Sent from my SCH-I535 using Tapatalk 2

My poor choice of the term; sorry. What my point is, is that this radio has current FCC approval for 10m use. So, it would have to have already passed spectral purity testing. Better?

 

[jessejamesdallas]

They used to have two 2290's in them.
When did they change?

I'm guessing when Toshiba quit making the 2290!

 

[AudioShockwav]

is that this radio has current FCC approval for 10m use.

Rob, there is no approval needed for 10 meter use/build.
None of the "ten meter" exports have any kind of approval/acceptance criteria, only the FCC type accepted CB radio`s go through that process.


73
Jeff

 

[AudioShockwav]

I'm guessing when Toshiba quit making the 2290!

Toshiba is still making the 2290, they just jacked the price up and call it a 2290B.

http://rfparts.com/transistors/2SC2290_Lot_Number_Description.jpg

2SC Transistors at RF Parts Company ( scroll down to 2290B )
They are using Mosfets Because they are Cheap compared to Bi-polar`s


73
Jeff

 

[WA2SI]

My poor choice of the term; sorry. What my point is, is that this radio has current FCC approval for 10m use. So, it would have to have already passed spectral purity testing. Better?

Gotcha!

Sent from my SCH-I535 using Tapatalk 2

 

[Shockwave]

This amp should run clean when properly driven because it has both bias for linear operation and low pass harmonic filtering on the output. It has four MOSFET's with a 60 watt dissipation. Best IMD results are usually obtained when the transistor is operated around half its maximum dissipation. So figure 120 watts PEP tops and I would run even less because I doubt the published specs are for 27 MHz. use. These transistors are cheap because they are switching transistors made for power supplies. They just happen to work here and may be stressed as a result of the higher frequency and linear operation rather then switch mode. Check for heat, if you can't hold the heatsink when talking, you're over dissipating.