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What device is this amp using ?
Posted: Thu Dec 29, 2022 5:12 pm
by XXL
Looking for what device this is. They’ve put a sticker over it but also been rubbed off once you remove it. They seem to use the same amp but change the chip for 120w - 200w and 300w
https://a.aliexpress.com/_mMaScr4
Re: What device is this amp using ?
Posted: Thu Dec 29, 2022 5:27 pm
by reverend
They use various devices, mostly taken out of old cellular amplifiers. The MRF9180 is one example.
Re: What device is this amp using ?
Posted: Fri Dec 30, 2022 3:28 pm
by BriansBrain
XXL wrote: ↑Thu Dec 29, 2022 5:12 pm
Looking for what device this is. They’ve put a sticker over it but also been rubbed off once you remove it. They seem to use the same amp but change the chip for 120w - 200w and 300w
https://a.aliexpress.com/_mMaScr4
Mmmmmmmmmm interesting
Operating power supply: 26-27V
Input power: 0.6-1W
High gain
Re: What device is this amp using ?
Posted: Fri Dec 30, 2022 3:45 pm
by XXL
Is that good or bad ?
Re: What device is this amp using ?
Posted: Fri Dec 30, 2022 3:54 pm
by BriansBrain
XXL wrote: ↑Fri Dec 30, 2022 3:45 pm
Is that good or bad ?
Good
Most 300W pallets are 4>5W input
Re: What device is this amp using ?
Posted: Fri Dec 30, 2022 4:24 pm
by BriansBrain
Here's another even cheaper About
€149.73
But without the LPF on ebay
ebay - 300W 75MHz-120MHz 1W RF Power Amplifier Board.jpg
300W 75MHz-120MHz RF Power Amplifier Board Input 27V Working Current 17-18A for FM Transmitter Radio
Specifications:
- Power supply: 27V
- Working current: 17-18A
- Power: 300W (maximum 350W 300W is recommended)
- Frequency range: 75-120MHz
- Input power: 1W
- Output impedance: 50 ohms
- Board size: 10 x 5.4cm/3.9 x 2.1"
Re: What device is this amp using ?
Posted: Fri Dec 30, 2022 5:00 pm
by BriansBrain
OK I'm guessing it's a
SRF261
It doesn't have the normal mounting flange with the holes for mounting
So they have soldered one on
300W 75MHz-120MHz 1W RF Power Amplifier Board - 2.jpg
Re: What device is this amp using ?
Posted: Fri Dec 30, 2022 5:23 pm
by BriansBrain
Re: What device is this amp using ?
Posted: Fri Dec 30, 2022 5:34 pm
by jvok
Reckon that heatsinks big enough?
Re: What device is this amp using ?
Posted: Fri Dec 30, 2022 8:01 pm
by XXL
Won’t that solder just melt with the heat ? Also what would the 200w device be ? I don’t think it would be an mrf9180.
Re: What device is this amp using ?
Posted: Sat Dec 31, 2022 12:01 am
by Albert H
The output short circuit test in that video is scary!
The harmonic outputs from that PA are rather nasty - the second is around 48 - 54 dB below the carrier, and the third is generally a bit worse. It would need a good lowpass filter after it to make sure it wouldn't cause interference. You'll notice that they've set the spectrum analyser to show only up to the third - it's probably producing more harmonics above that. The lowpass filter capacitors will be expensive, since they'll have a pretty big voltage across them.