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LA-250

posted Sep 23, 2016, 10:06 PM by Charles Boling   [ updated Aug 8, 2017, 1:17 PM ]
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.

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Charles Boling,
Sep 23, 2016, 10:06 PM
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Calibration.txt
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Charles Boling,
Sep 23, 2016, 10:06 PM
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