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Reviews For: RM Italy LA250 VHF amplifier

Category: Amplifiers: RF Power - 6M/VHF/UHF+

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Review Summary For : RM Italy LA250 VHF amplifier
Reviews: 5MSRP: 559.00
Description:
The LA-250 is a 200W 140-150MHz amplifier, at 1 to 20W input (13.6V 30A). It uses 4 Mitsubishi RD70 Mosfets mounted on a copper heat spreader (200x60x3mm).

It is available in two versions one with and one without top mounted fans. There is an external PTT input but it can be used also without due to the built-in HF-VOX. The front panel features an LCD display which shows input power, output power, heat sink temp and output VSWR. There is the ability to change the intensity of the backlight.

The CPU keeps an eye on input power, temperature and VSWR and will if necessary disable the amplifier from transmitting if there is fault. Any errors will also be recorded and will be available for later recall for diagnostic purposes by either the manufacturer or his distributors.

Weight is approximately 4kg. Dimensions are approximately 240x420x70mm for the non fan version and an extra 10mm of height, 80mm, for the fan version.
Product is in production
More Info: http://www.rmitaly.com/index.php/en/products/amplifier/item/978-la-250
# last 180 days Avg. Rating last 180 days Total reviews Avg. overall rating
0054.2
KD9VV Rating: 2022-01-24
Solid Amp Time Owned: 0 to 3 months.
I purchased this amp primarily to take the load off my IC 9700. I am drivng this amp to 200W with 12W in.

My primary use is digital modes, FT8, MSK144.
I don't have a spectrum analyzer so can not speak to it's spectral purity, although I believe it's ok as I've made many digi contacts.

I detect no significant insertion loss.
Following are what I consider to be negatives:

1) Stray RF.
2) Poor digital readout unless the amp is at eye level.

I first had a Astron 50A switching PS inches from the amp. This caused problems as stray RF from the amp affected the power supply. The PS was barely putting out 8 amps; the amp could not put out more than 130W.
By moving the PS 4 feet from the amp solved this issue.
Best guess is that the amp is not well shielded.

All in all it seems to do the job well; I have no concerns running this amp at its full rated output.
I even went key down FM for 1 min; still the fans stayed on their default low speed. I probably did not need the fan version.

Best practice is to key the amp directly rather than RF sense. I have a hunch RF sense is causing relay chatter by watching the current change during TX.
VK2FZR Rating: 2020-06-17
Im not selling it now. Time Owned: more than 12 months.
I have had this amp for 3 years and had nouthing but trouble with it, so much I almost sold it. Until I spoke to a ZL station who just so happened to be the ZL importer for this amp. I told him it would constantly trip out and I could only get about 160w TX and there was no way I could get 200w out of it. He asked me was it getting hot? NO. What was my voltage input? 13.8v. He said the amp measures several things at once and if 1 isnt right the it will shut down, he said the over drive was tripping out because I was driving it to hard to try to get 200w out of it so he advised to turn the voltage up so I did to 14.7v. now it will gladly give me 200w, 207w on voice peaks. It is now doing what it is supposed to do. Im not selling it now.
IU2GID Rating: 2018-01-23
perfect for portable / field day Time Owned: more than 12 months.
I'm using an LA 250V (the one with fans) for contesting with portable setup. I know that for serious troposcatter a 500 W PA is minimum but for portable operation with 12 V batteries 200 W is the best I can find on the market. I use it with 12 V SLA cell, no inverter, no power supply.

I measured the insertion loss with an SDR and it's about 0.2 dB. The pickup noise is negligible so I have to disagree to who says it's about several dB. I can't tell the difference while receiveing with and without it on an Airspy SDR and on a Kenwood TM-255E (known for the good sensitivity).

The onboard power meter is not a calibrated instrument and does not measure SSB PEP. You can only use it as a indication on FM.

With the TM-255E at first I had some problem of overshooting that put the LA 250V in protection but then I calibrated the radio to avoid the ALC involvement and to output about 10 W in low power mode. This ways I no longer have protection issues and I have about 170 / 180 W output. Reports on voice quality are always good.
AD7UF Rating: 2016-09-23
Powerful, with "rough edges" Time Owned: 6 to 12 months.
THE GOOD:
- Glad I didn't get the fans -- I don't see that it would need it unless you were running 100% duty at high power.
- Amplifies as advertised. I tested at drive levels from 1/2-30W (5-25 in 1W increments), and actual output hit ~200W @ 5W and 250W @ 10W in. Casual SSB listening showed output to be reasonably linear at all power levels.

THE BAD:
- The amp's power meter's off. Input reads ~40% lower than actual. Beware - this also affects the over-input protection! Output also read 20-40% lower than actual, depending on level.
- The bypass isn't a 100% bypass. If you want to run a radio w/ more than 50W, or use UHF, you must completely switch this amp out of the circuit. I repeat: do not try to use 70cm through the amp, even in bypass mode.
- Not only does it lack a receive preamp, but with the amp in-line, I find that signals degrade by 6-10dB by my guess. Yes, it's bad. If I'm working a station weak enough that I feel the need to use the amp, I often have to switch the amp out (tedious - 2 coax switches) to still hear them.

THE UGLY:
The stick-on front panel wasn't aligned quite right and the screws forced it over. It unsticks and bulges out in a couple of areas. Disappointing for such an expensive piece of equipment.

THE GRAPH of the power readings and more details on my test methodology can be found at http://www.mmsherc.net/happenings/la-250
W1ZZK Rating: 2015-04-16
Great performance and reliablity Time Owned: 3 to 6 months.
I have used this amplifier nightly for 3+ months with no problems. It's a winner!

When fed with 11 watts from my TS-790A the output is 204. Heat is no problem, even without the fans. With only 2 watts in, the output is 125 watts (this is where I run it mostly). The amp is physically very large.

I really like the display. It shows input power, output power, SWR and heatsink temperature. It has foldback and will operate to 2.8:1 VSWR. I have tried all the protection features and they work perfectly to protect the amp.

My only wish is that it had a low noise receive preamp.

Although I have had issues with previous versions of RM Italy VHF amplifiers, this new design is rock solid. I can recommend the LA250 amp.