LA-250

Post date: Sep 24, 2016 5:6:45 AM

8 months ago I bought an RM Italy LA-250 linear amplifier for 2m. I gave Frank at rmitaly.us some feedback on it shortly after purchase, and I'm finally getting around to posting it as a review. Since eham.net doesn't allow attachments on reviews, I'm also posting the info here so I can include my input/output power graph.

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 simplex station weak enough that I feel the need to use the amp, I have to switch the amp out (tedious - 2 coax switches) to still hear them. It is a good amp for working "alligator" repeaters,

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.

Power Meter details:

Attached are a couple of files; the the PDF shows a graph, and the text file (copied from my email to Frank) elaborates on my test methodology and the significance of various values.

More on the poor receive (Aug 2017):

The amp acts as a receive antenna, picking up local signals (and RFI) from within the shack very nicely. This is true whether or not it's turned on, and seems to be a big part of the received signal degradation -- it's not so much that the received signal is weaker, but that the noise floor comes way up.

It has no chassis ground connectors, and I have not played with additional grounding.