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[K1KIM]

There is absolutely no warranty applied or given on these items. No factory support either.

These units are for industrial, scientific, medical, or export use only. It is a violation of US FCC regulations to operate these units on the Citizens Band or Amateur Radio Services in the United States. Please check regulations in your country before operating these unit.

This is on the bottom of each item description.

I see that when you pull up each model.
There are many well respected dealers here in the USA that sell the same with no disclaimers. Maybe the ones at Anderson are not US models. 

Here's a link to DXE for similar US Models.

https://www.dxengineering.com/search/brand/rm-italy?SortBy=Default&SortOrder=Ascending&keyword=rm%20italy&kr=rm%20italy

[N8YX]

I'd look at a marine or fixed-station amp capable of 100% CCS.

The rigs I most often use for 10FM are CCS rated at 100-150w, and I find I don't usually need an amplifier to maintain a decent signal to the other guy. 

[KM3F]

The traditional SS amplifier for SSB will also work for FM and CW as long as SSB is specified for the given amplifier..
However SSB needs a key-up holding circuit to prevent unkeying between words. This is usually built into the design and may be adjustable in holding time.
For FM use only, the holding circuit will stay keyed as long as there is Tx RF drive applied.
There is no difference between CW and FM drive signal except CW keying intervals.
.
The biggest difference is on AM. The carrier is no different than FM but the >modulation applied< raises the drive power peaks that follows the Audio applied from the transmitter. This must be accounted for in the carrier power level setting  to allow for the voice peaks. If this is not done, the amplifier can be over driven on the higher voice peaks. For example: an Amplifier rated at 30 wats drive and 160 watts out FM or CW will require an AM carrier of about 8 watts drive into a 30 watt drive rated amplifier. Why? The traditional modulation for 100% is 4 times the carrier drive. This means that 8 watts carrier drive times 4 = 28 watts voice peaks which is the max for the amplifier. Making 8 watts look unusual when in fact it is about correct. Now even this drive level is still too high because it will drive the amplifier into gain compression on voice parks.
FM does not care about gain compression being FM because the drive is constant and not varying in level..
The correct drive then becomes a level that will keeps the amplifier working in it's most Linear input/output curve and stay reasonably clean for on air signal quality without flat topping on voice peaks that causing  distortion and splatter..  This drive level will be as low as 5 watts which will reduce the amplifier output on AM to about 100 watts out of it's max of 160 on FM.
So you see there is more to all this than meets the eye, you must understand.
.
Lastly, the fined heat sink should be kept below about 150 *F in fin temps to keep from losing the RF to
 overheating shut down or damage on long and close spaced transmissions. To aid this possibility from happening, a Cooling Fan should be mounted blowing down on the Heat Sink Fins.
.
The above is not often spoken about and leads to a lot of SS amps being blown due to misuse and not understanding each mode requirement.
As a user, you have the responsibility to understand all the operating mode requirements of use for good practice.

[W1VT]

I think the number one reason for blowing SS amps is unintentional overdrive.
Rigs  have low power settings but if you look a the signal with a Bird peak reading wattmeter, you will often see peaks close to the high power rating of the rig!
These peaks are very short, but still long enough to blow solid state devices.

[WB6BYU]

Just to be clear, we are talking about two different factors here.

The first is the operating mode:  any amp rated for SSB or CW
will amplify FM without any distortion, whereas an amplifier
designed for CW may not be "linear", and can cause massive
splatter on SSB or AM.

The other factor is the required cooling to maintain the rated
output power.   CW has about a 40% duty cycle when
transmitting, while FM runs 100%.  (SSB often is less than
20% based on average output of a voice waveform.)    That
affects the heating of the output devices.  So you may need
to run the amp below the rated output power, or add fans or
otherwise improve the cooling system, when using FM.

An infrared thermometer is cheaper than a replacement set
of finals.

[N7EKU]

RM Italy KL35 is 1-5w in 35w out for HT's

RM Italy KL503 I believe is 12w in 250w out on FM  450w on SSB

They have several 10M FM capable amps.

Buy here in the US

One place to buy. https://www.andradsupply.com/amps.php
There are several others

As you noted in later posts,

These lower-priced 10M RMItaly amps are not legal for amateur radio use in the US, and likely it's the same in many other countries.  These amps have zero low pass filtering (schematics are available on the manufacturer's website) so they will generate harmonics all the way out into the VHF and UHF bands.

Basically still "you get what you pay for" works.  The lower-priced amps are lower priced because they don't include filtering which costs money.  For HF use, a solid-state amp needs up to seven low pass filters to cover all the bands and each filter required a set of toroidal inductors and HF capacitors plus a switching mechanism is needed.

You could buy one for single band use and then add your own low pass filter.  You would just have to be careful not to overdrive them which is easy to do because RM Italy at times claims higher output than the amps can do cleanly (google for studies done by hams).  Kind of like the old days with the lower priced car audio amps!

73

[VE7RF]

RM Italy KL35 is 1-5w in 35w out for HT's

RM Italy KL503 I believe is 12w in 250w out on FM  450w on SSB

They have several 10M FM capable amps.

Buy here in the US

One place to buy. https://www.andradsupply.com/amps.php
There are several others

As you noted in later posts,

These lower-priced 10M RMItaly amps are not legal for amateur radio use in the US, and likely it's the same in many other countries.  These amps have zero low pass filtering (schematics are available on the manufacturer's website) so they will generate harmonics all the way out into the VHF and UHF bands.

Basically still "you get what you pay for" works.  The lower-priced amps are lower priced because they don't include filtering which costs money.  For HF use, a solid-state amp needs up to seven low pass filters to cover all the bands and each filter required a set of toroidal inductors and HF capacitors plus a switching mechanism is needed.

You could buy one for single band use and then add your own low pass filter.  You would just have to be careful not to overdrive them which is easy to do because RM Italy at times claims higher output than the amps can do cleanly (google for studies done by hams).  Kind of like the old days with the lower priced car audio amps!

73

Without a LP filter, the wattmeter is gonna read somewhat higher.   Odd order harmonics are not suppressed very well, typ 10-13 db.   For a mobile application, it's not too big an issue, since the typ mobile ant is not resonant on it's harmonics.

Zak is correct, xcvr's like the Icom 745 will put out a 150 watt spike, regardless of power setting.
A 9 vdc battery across a 500/1 megohm pot, with negative Vdc coming off the wiper..then fed to the ALC input on the xcvr, will usually solve the initial spike issue.  Tweak pot for desired PO.  You don't have to wait for ALC to be developed, since it's already there at all times.  Set it for say 56 watts pep out..and that's all ur gonna get.

[AC2RY]

Zak is correct, xcvr's like the Icom 745 will put out a 150 watt spike, regardless of power setting.
A 9 vdc battery across a 500/1 megohm pot, with negative Vdc coming off the wiper..then fed to the ALC input on the xcvr, will usually solve the initial spike issue.  Tweak pot for desired PO.  You don't have to wait for ALC to be developed, since it's already there at all times.  Set it for say 56 watts pep out..and that's all ur gonna get.

Why would someone use 40 years old ICOM (released in 1983) with modern amplifier?
Why would someone use solid state amplifier that has no integrated protection circuit from overdriving?

Simply accept that 3/4 of modern amplifier circuitry is dedicated to protection of the remaining 1/4 from various fault conditions.

[N7EKU]

Hi,

Well in the US it's pretty clear that our amateur radio license requires us to operate within the rules established for us and our equipment.  There are specific requirements for amplifiers that don't include using antennas as harmonic filters -- the level of harmonics are specified as that coming out of the amplifier itself.  Besides if one wants to use one of these cheaper amps mobile, how difficult is it to just add a low pass filter?  In the spirit of amateur radio, one should be willing and able to do that!

As a side note, I think 1/4 wave verticals can work fine on their 3rd harmonic which is in fact the harmonic that needs to be cut down on push-pull amps.  But regardless, resonance is not necessarily an indicator of whether an antenna can output RF or not.

73

[WB8VLC]

I looked around he net and tried to find some info first, I have been listening and talking to some fm stations on 10 meter 29.6.
It would seem to me that FM Hf amps a few and far between? I searched and I didn't find any except for kits from chinese sellers.
I don't need one for home, I think a 7300 is just fine, but I have a little 10 11 meter radio that does fm, it would sure be nice to
be able to have an amp for that.
So most amps are for cw, ssb maybe Am and rarely for fm, does that make sense?

Once in a while I will my push pull home brew Microsemi  VRF2944 TMOSfet amp with my 12 watt K3S driving it and this amp is one that I built from an app note years ago.

 I only use this much power on 10 FM for the really long, really tough FM contacts such as some of the recent eastern Europeans and Middle east hams on FM from here in Northern Oregon.

 Even this much power is rare for me these days since I have a large 4 element 10 meter OWA that usually only requires 60 watts from my Motorola Maxtrac on FM.

For the TN8K african dx pedition which was on 29.050 FM a few weeks ago he was so strong that I used my 60 watt Motorola Maxtrac and my 4 el OWA so the Microsemi amp is only used these days on bands where I have mediocre antennas or for really long haul FM qso's.

TN8K was fun and stressful  having to reprogramming the maxtrac on the fly for 16 different frequencies where I hoped that TN8K was listening and it paid off easily in the end.

Since my 10 meter antenna is the best antenna that I have, I mainly use this amp now loafing along at  700 -900 watts output on the other HF bands where I have mediocre antennas such as COMTEX phased verticals which are just big dummy loads anyway.

I built this amp from an old APP note that Microsemi in Bend Oregon pout out years ago, along with some W6PQL support circuitry to package it into a usefull project and I have never experienced an issue with the 2944's TMOS devices.