RM Italy KL 7405V 10 meter Linear Amplifier With Fan

[Big Kahuna]

Why?

I'm the same, I have a meter in line all the time. Sometimes a cable gets bumped, something comes loose, etc. Every time I turn the radio on to talk I check SWR, output, etc and then begin talking. I had an experience in the mobile where I forgot to hook up antenna after switching things out, luckily saw the issue on my meter before I turned on the amp

 

[Shadetree Mechanic]

Why?

Incase something happens to the coax or antenna. Bad connection, water intrusion coax meltdown etc. It's important to know that everything is good when you hit the key. Especially when running power.

 

[Ziploc]

Incase something happens to the coax or antenna. Bad connection, water intrusion coax meltdown etc. It's important to know that everything is good when you hit the key. Especially when running power.

That would have saved me chasing my tale then remember?? Short out jumper from radio to amp was cause my amp pills to short

 

[Shadetree Mechanic]

Whenever I power up my station, I check swr, dead key and peak power of the transmitter. Then I turn on the amp and check it all again. If I run a driver, I check it and then turn on the final amp and check it. If something is not right at any step of the way, I do not proceed.

 

[NightThumper]

Incase something happens to the coax or antenna. Bad connection, water intrusion coax meltdown etc. It's important to know that everything is good when you hit the key. Especially when running power.

Same here. In fact my big base station amp is setup to automatically un-key if my SWR exceeds 2.

 

[Ziploc]

Same here. In fact my big base station amp is setup to automatically un-key if my SWR exceeds 2.

My linc / plus has a swr shut off

 

[NightThumper]

My linc / plus has a swr shut off

Remember if you’re using an amp the Lincoln SWR shut off is based on what it’s seeing on the amp input if the amp is on. If the amp is off your Lincoln is seeing the antenna SWR because the signal/RF is simply being passed through the amp when off. Technically this could mean the amp is experiencing high SWR on the output....between the antenna and the amp but between the radio output and amplifier input everything looks fine.

My shutdown protection is between the amp output and antenna.

 

[Slowmover]

Remember if you’re using an amp the Lincoln SWR shut off is based on what it’s seeing on the amp input if the amp is on. If the amp is off your Lincoln is seeing the antenna SWR because the signal/RF is simply being passed through the amp when off. Technically this could mean the amp is experiencing high SWR on the output....between the antenna and the amp but between the radio output and amplifier input everything looks fine.

My shutdown protection is between the amp output and antenna.

IIRC, it’s a menu option on the Linc for SWR protection, isn’t it?

Of what does your “SWR protection” consist?

.

 

[NightThumper]

Slow…you’re right on the Lincoln it’s a menu option for SWR protection, both to turn it on and set the SWR at which the radio will shut off. By the way that feature does work as I accidentally one time forgot to turn my antenna switch over to the Lincoln.

Only on my manual keyed amp can I set an SWR or power level protection. The Telepost allows setting those protections as I run my IC-7300 keying line through them. If the Telepost senses either high SWR or a high power situation it cuts the keying line to my amplifier. So if the radio has a high SWR feature it cuts off input power and if the Telepost senses high SWR or Power on the output it breaks the keying line going to the amp.

I would like to be able to set my RM Italy amps to be manually keyed instead of RF. RF sensing is more appropriate for vehicle situations but not for my base station usage.

I haven’t tried this yet but I think I can use the Telepost I’m using to measure input to key the second Telepost which in turn keys the amplifier. This would also allow me to set two fail safes on the input and output.

 

[Slowmover]

The RM ITALY KL-7405 seems to be a good match to a new (side mic) Galaxy DX-959b in the Kenworth t680 I’m driving at present.

I don’t have radio/amp/mic as closely matched as I’d like, so TX still needs work.

RX is flat awesome.

This amp as big as I was comfortable with for both amp draw + physical dimensions. 44’ power circuit.

I haven’t run into a situation on-highway where I haven’t been heard. About a month after install finished. So it’s not much of a claim so far.

Antenna system is a WILSON cophase harness with Palomar Engineer coax filters at the three ends. Out to seven-foot Skipshooters. (Am pulling a 53’ reefer).

.

 

[Switch Kit]

I got a KL7405 (not V) new in the box a few months back , I'm no amp guy that's for sure but I have used a lot of them over the years and experience and listening to those that know have always helped me out a lot over the years (much thanks for those who have taken time to help out when they could) The KL7405 is a very nice well built AB 2 X 455 amp , it's really to bad about the heat sensor in the face plate that makes it shut down as it can , (I blame the makers on this one ?) I know in So.Cal I could never run this thing in the car because of the heat sensor . (unless it was cooler in the winter time) Talk about a pain in the ass !

I wasn't about to drill holes and add another fan in order for it to work as it should in warming conditions . The amp gives me 120 clean talking watts on SSB and AM all day long with a good SWR , the fan is a very nice touch and speeds up while talking , (Noise of fan ? doesn't bother me in the least !) Driven with a old school 148GTL about 1.5 watts and swing from there on AM and about 12 watts on SSB . I use the amp in the house , I added longer screws to the face plate with about half inch spacers and put some rubber feet on the bottom and it has not shut down on me since and I talk on SSB 90% of the time. (and long winded , my bad )

That heat sensor from factor was a real blunder on such a nice little amp but it can be worked around but still a pain in the dairy aire one way or the other. I'm just old school and MOSFETS are just not my piece of cake and it sure seems like a MOSFET world these days. It looks like RM Italy is running the amplifier show these days ? other then Texas Stars ? and looks like they have put a lot of old school amp makers out of buisness ? I really don't know but the times they be a changing for sure. Switch

 

[AudioShockwav]

Switch there is a builder here in the US building MOSFET amps called Rocket Box Electronics.
They seem to have evolved into a decent amp.
I have old school stuff but I see good reviews on these amps online and no complaints so they must be doing something right.

73
Jeff

 

[Switch Kit]

Switch there is a builder here in the US building MOSFET amps called Rocket Box Electronics.
They seem to have evolved into a decent amp.
I have old school stuff but I see good reviews on these amps online and no complaints so they must be doing something right.

73
Jeff

I don't doubt that Jeff , like I said , it surely seems like a mosfet world these days , even Chris Holland makes a few of his own in Ontario and hear tell there good amps , I know some guys running the RM Italy 703s and they sound good on about 500 watts SSB and they love them. I can understand they are way cheaper then transistors that's for sure , the economy has surely blown my mind with the prices I have been seeing for used amps and radios ????

Never thought I would have to see a buck a watt or more used and new ! With mosfets being as cheap as they are but yet the cost ? and I surely hear you on that "they" must be doing something right . About 14 years ago I sold a few 800 watt mosfet amps for a private builder at the time but as I recall I think I got around 300$ for them new , I used one myself in my car and this is when I had a bad experience with one , was working great ! I was on a perch doing my thing and once I started to come down I was still talking and the amp blew up ! I had to pull my car over immediately ! there was so much smoke I couldn't see or breath !
So what happen ? I was coasting down that hill and the voltage dropped and did them in ! Up in smoke ! that's when I learned that voltage drops on mosfets will blow them more so then amps or both, but was a way cheap fix but again that was 14 years ago . (I can still smell the smoke just thinking about it !) I'll have to look into the Rocket people ? I gotta Mega-Watt 50 amper a few months back and I have been very impressed with it and the cost ! ( Very good deal on those even in this economy ! ) I can see where makers have gotten better with the mosfets over the years and to there advantages as well as the users. By the grace of the powers that be I can still learn some things as I go along ......Switch

 

[BigLou]

IiJust a word or two on the RM 703 like you I. think the rm,s are a fine amp and I have had the 703 now for going on a year . I run the 703 at 450 watts out on high. Most of the time it,s on low at 175 watts or so it,s all I need .