Using the FT-817nd with a “dirty amp” (RM KL300P)

FT-817 with the RM KL300P

FT-817 with the RM K300P

Lately I’m trying to improve my portable HAM Radio setup because I want to do some activations for Castles On The Air (COTA) and WorldWide Flora & Fauna (WFF).

The idea for the activations is that you take all the HAM radio gear you need to make your contacts and carry them to the end location which can be in my case a castle or a nature park. From there you will then make your contacts.

You can imagine, if you need to carry everything to your transmitting location, you want to carry as little as possible! And so started my search for the best and lightest HAM setup possible. 🙂

My Setup

At the moment I’m using the Yaesu FT-817nd plus a manual tuner with built in 1:4 balun so I can use a random length wire antenna with that. I’m using a lot of different antenna’s by the way, depending on my mood and the circumstances.

I’m also a fan of the Hy End Fed which is an end fed antenna made by some guys here in the Netherlands. It works on the 10m, 20m and 40m band and doesn’t need any tuning. Plain, old  home brew monoband dipoles are also great in a lot of circumstances. I made a lot of them, using them in all kinds of situations.

Although I also have a Yaesu FT-857D I prefer the FT-817nd because it works also just on batteries. With that you have the lightest setup possible! Just the FT-817nd, a tuner and an antenna wire will already do the trick! 🙂 And the FT-817 is just a nice little rig, almost a toy, so I anyway like it.

For my battery power I just bought a Tracer 12 volt, 14Ah Lithium Polymer Battery Pack. Although not very cheap, it is small and light and should give me enough juice to use the FT-817nd together with the KL300P. I replaces the connection on the Tracer with some Anderson Power Poles to make connecting things to it a bit safer and easier.

Tracer 12v 14Ah Lithium Polymer Battery Pack

Tracer 12v 14Ah Lithium Polymer Battery Pack

More Power!

Because the FT-817nd has a maximum of 5 watts I was looking for some more power. When you go through all the trouble of walking to the activation location you want to be able to talk to people in the end, also if propagation isn’t so great!

I know there are some nice HAM linears available but they either are to big, to expensive or both! The Tokyo HighPower HL-45B is one of those and I do also like the RM HLA 150 linear from Italy. They both have all the band filters built in and give a pretty clean signal for this type of amplifier.

The RM KL300P Linear Amplifier

The RM KL300P Linear Amplifier

I decided in the end to go for the RM KL300P linear. It’s a small (!) HF linear with max 300w output on SSB when driven by max 10w input. The bad thing about it is that it doesn’t have any filters built in. The good thing though is the size (!) and the value for money.

RM HLA 150 with the RM KL300P

(Small) Size Matters!

The price of the KL300P is around 135 euro (185 USD) and will give you 300 watt, so it’s very affordable! The Tokyo HighPower (THP) linear in comparison costs 670 euro (925 USD) and will give you 45 watt(!)

A quick calculation shows me that the THP gives me 1 watt per 20.5 USD, the KL300P gives me 1 watt per 0.61 USD! The THP will give you bandpass filters though, that are missing in the KL300P but still, the price difference is just to much! Especially as, in my case, you are not using it very often. Next to this the THP is just to bulky to carry around with you and is in all aspects not an option for me.

I know the Italian RM linears are not allowed in the USA but in most other countries they are. In the Netherlands, where I live, you’re allowed to use any equipment if you have a HAM license as long as you keep to the rules of your license. I have a full HAREC license (comparable to the Extra license in the USA) so I’m allowed to use any and all HAM radio equipment.


I would not use these RM linears from home without adding good filters, for sure a low pass filter to keep the neighbors happy!  My base setup is a Yaesu FT-1000mp Mark V plus an Ameritron AL-811HD linear amplifier so at home I anyway don’t need the KL300P.

As long as you don’t over drive the RM linear the disturbance to other HAM operators can be kept to a minimum, I think. The FT-817 anyway doesn’t have more than 5w which is halve of what you can use to drive the linear on SSB. And of course, when you use the RM linear close to buildings or places where people live, you should at least use a low pass filter. One that cuts off all harmonics above 30 mHz that could otherwise show up in some electronic equipment.

The low pass filter still doesn’t remove all interference but it’s a minimum addition when using the linear at home I think.

To get the same power the Tokyo High Power gives you (45w) you only need to drive the KL300P with 1 watt. In the specifications it says this is not possible on SSB but in practice it is and this will give you about 40w output.


I did some quick tests using the KL300P with the FT-817nd, driving it with maximum 5 watt and found that the values in the following table were reached. The amount of amperes needed is also very important to me because this shows me what battery to take.

FT-817 input KL300P output Linear Setting Amperes
5 w 170 w HI 17 A
5 w 90 w LO 13 A
2.5 w 110 w HI 15 A
2.5 w 40 w LO 8 A
1 w 50 w HI 10 A
1 w LO

The tests that I did were very basic, using the KL-300P, a 13.8V power supply, a 1:1.2 20m dipole and an FT-817nd. I tested around 14.200mHz and used an MFJ tuner and an Ameritron AWM-30 (analog) watt meter.

One, for me not so positive point about the KL300P (next to the no filtering) is that when you turn on the linear, you also get the pre-amp “for free”. You cannot turn the pre-amp off when you’re using the linear. Especially in situations when there are some strong stations around you don’t always want a pre-amp.

Another point to think about is that the linear works with a SWR of maximum 1:1.5 (!) So you should have a good antenna and / or a good tuner to get the SWR as low as possible.

All in all, if you look at what you get for the money it’s a great little amp that makes my portable configuration perfect….. for now…. 😉

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8 Responses to "Using the FT-817nd with a “dirty amp” (RM KL300P)"

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