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Amp Suggestions

dlwarnbergdlwarnberg Member
I have a FLEX-6500, 43' vertical, looking to possibly add and AMP this year.  This will be my first amplifier so excuse all the questions.

I want to run the amp from 120 volts (possibly switch it to 240 in the future if possible)
I think I want a linear amp (suggestions)
Not necessary to go full legal limit (think 1000 watts will be plenty)

So, what are you experiences with Amps that work well with these Flex radio's?

I thought I read somewhere FLEX is looking to make an amp, what is the latest info on that?



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  • WA2SQQWA2SQQ Member ✭✭
    edited January 2017
    I use an Acom 1000. Incredible buy for the price. I think it can be rewarded for 120. No regrets buying it. Reliable, covers 160-6 and very easy to tune up. It also tolerates SWR up to 3:1.
  • RFordRFord RFord - W4RJF Member ✭✭
    edited July 2017
    I run an Acom 1000 on 120...work's great with the Flex 6300...
  • Rob N4GARob N4GA Member
    edited January 2017
    I built my own LDMOS solid state amp. It's awesome. Nicest amp I've ever owned..

  • WA2SQQWA2SQQ Member ✭✭
    edited January 2017
    Acom is a super easy interface to my 6500
  • Jim GilliamJim Gilliam Member
    edited May 2019


    Can't go wrong with this one.

  • KF4HRKF4HR Member ✭✭
    edited March 2017
    I use an ICOM PW-1.  It works fine and my Flex-6700 easily drives it to 1kw output.  I've read other Flex users are successfully using the Expert line of amps as well (1k, 1.3k, 2k).  I'm planning on selling my PW-1 and upgrading to a 2K-FA eventually.

    If you run a 1000w amp on 120vac, and plan to run full power, I recommend using a dedicated 120vac 20A circuit, as the 120vac circuit you choose may have other loads (lights, radio equipment, etc).  If you don't have a dedicated 120vac 20A circuit another option is to limit the output power of the amplifier.       

  • Roy LauferRoy Laufer Member ✭✭
    edited May 2017
    What about the SPE 1.3K-FA? It's so popular that it is still on backorder with the manufacturer. It's small and light and very energy efficient.
  • K1UO - LarryK1UO - Larry Member ✭✭
    edited December 2017
    You might look at the SPE1Kfa amp also.  Solid state, fully automatic 160-6 meters and has its own built in antenna tuner.  As KF4HR said above..If you use it on 120V circuit then put it on its own dedicated 20A circuit.   The SPE1k is more readily available new and used and might also be available from some Dealers who took trade ins for Amp upgrades.
  • edited February 2016
    I now have 2 Flex 6300 and I run a Ameritron AL-600 on both of them. I had the amps before i upgraded to the Flex and have not had any problem with them. Yes they are only 600 watts but I also have a AL-1200 I used for a little while and I would switch back and forth with the same antenna and band conditions. Unless you are trying to bust a pile up there is not much difference on the receiving end between 600 and 100 watts. I know they are not the highest quality or priced amps and I purchased both of mine used for around the 600$ mark but they have served me well. If I was going to run much more than 600-800 watts I would take the time to put in a 220 circuit. I did that for the Al-1200 I do not think it would have worked on a 115 volt circuit, at lease not well. 
  • Walt - KZ1FWalt - KZ1F Member
    edited May 2019
    I ha e an Elecraft kpa-500 and kat500. It is nominally 500w but can easily do 650w and above. It's a fantastic linear and runs fine on 115v but is switchable to 230v should you want to.
  • Ian GM4KLNIan GM4KLN Member
    edited December 2019
    Hi David
    It may be useful to consider what modes you like to operate, as that defines the duty cycle: I like to run digital modes such as RTTY, JT9, JT6m etc. and these are harder on the amp (I have the excellent Acom 1000) but it strolls along at 350 watts or so.....matched to my 6300. 
    Think too whether you want valves or solid state; manual or auto-tune. do you want 50 MHz too? built in ATU?  and so on. 
    in other words...have a think about what your needs are now, and could grow to be..and then look for a match. I'm sure many of the main candidates have already been proposed....
  • dlwarnbergdlwarnberg Member
    edited February 2016
    Well.. I was not going to use the amp when using digital modes (JT65, JT9, RTTY, PSK31, etc...) I don't see the need to in those modes, I can easily make contacts now in JT9 or JT65 with 15 watts or less.  

    Mainly the amp would be used for SSB Voice.. I am finding I can hear stations easily yet they can't always hear me (I equate this to the superior receive abilities of the FLEX 6500) 

    As far as tuners are concerned, I have the ATU in the 6500 as well as a separate Palstar AT2K.  So a built in tuner in the Amp is optional to me, but for quick band switching (Chasing DX) the built in tuner would be of great benefit. 

    I currently don't really do much with 6 meters, however there is always the possibility that when I retire (yes thinking about retirement finally) I plan on property where I can have the antenna to be able to work 6 meters as well, right now I'm limited... 

  • Steve (N9SKM)Steve (N9SKM) Member
    edited May 2016
    I run an Acom 1000 and like it and have a remote tuner for the antenna (also running a 43 foot vertical due to QTH) I love the tuning indicator on the amp and the protection that Acom has built in. As others have said if you run it on 120 you still really need to have a dedicated service for it so you may as well run 240.
  • Ross - K9COXRoss - K9COX Member ✭✭
    edited May 2019
    To quote a line from the National Lampoon's Vacation movie "How much you got".
  • dlwarnbergdlwarnberg Member
    edited February 2016
    That will depend on bonus..   but not thinking that will be much of an issue, it's when the wife finds out how much I spent is the issue...   HEHEHEHE
  • Jim GilliamJim Gilliam Member
    edited February 2016
    Brain washing wives is something that should be part of the learning curve of developing yourself as an A-1 amateur.
  • dlwarnbergdlwarnberg Member
    edited May 2019
    I'm kinda bummed, ACOM doesn't have a booth at Hamcation... Expert Amps does though....
  • AE0MWAE0MW Member ✭✭
    edited December 2016
    You're a brave man, I've never tried to drive my KPA-500 that hard!
  • Doug HallDoug Hall Member ✭✭
    edited February 2016
    The KPA-500 is a rugged little beast, including the PA transistors. It'll protect itself from just about any injustice inflicted upon it. The TX IMD suffers at the higher power levels, however.
    Doug K4DSP
  • Barry N1EUBarry N1EU Member ✭✭
    edited December 2016
    The TX IMD suffers at the higher power levels, however.
    Nothing that a little adaptive pre-distortion couldn't fix.

    73, Barry N1EU
  • Tony C kc2disTony C kc2dis Member
    edited May 2017
    I use a ameritron al 80 b. This is my first amp. Works great. I cant seem to figure out the hardware alc thing. But it has been a wonderful am so far...
  • Ken - WA8JXMKen - WA8JXM Member
    edited February 2017
    Good comments so far. At the lower end of the price spectrum, I bought a used Heathkit SB-1000 ($700 on eBay.)  It works well with the Flex 6300 on SSB and CW (rarely need it on CW), runs on  110v and makes a worthwhile difference when conditions are difficult.  

    If you are using a vertical, make sure you have plenty of radials.
  • Jim GilliamJim Gilliam Member
    edited February 2016
    ALC is a circuit that senses when the amplifier is overdriven and sends information back to the transceiver/tranmitter to reduce its output. It is used to protect the amplifier from too much drive and to reduce distortion.
  • wg cwg c Member
    edited February 2016
    Most likely just about anything will work, but the ACOM 1000 is the way to go.  160-6 for the $$ is the way to go.  Sure you have to tune it but it's like the good ole days!
  • RegReg Member
    edited November 2016
    I have an ALPHA 9500 and an SPE 1.3K-FA.  They are both supported by DDUtil.  On 110V the 1.3K-FA will put out a solid 900W.
  • KY6LA_HowardKY6LA_Howard La Jolla, CA. Paris and Sablet FranceMember ✭✭✭
    edited May 31
    I have an SPE 2K-FA at Home and we use ACOM and ALPHA's at the Contest Station.

    The 2K-FA will key down about 2300W into a dummy load all day and keep on ticking.. It is almost completely idiot proof, it is instant ON -  Definitely my preferred AMP especially when I am remote because it is idiot proof...and I sometimes do idiot things 10,000 miles away...

    The ACOM's and ALPHA'a are HOT.. Quite Noisy...Take 3-4 minutes to warm up and use very expensive tubes that need to be replaced regularly (if you abuse them in contesting) and likely will become unobtanium....They do produced better IMD than does the Solid State Amps. but not that significant in contests as the other guys will copy the crappiest signal for a Q

    I personally prefer that Autotuning Amps - my first Amp was the first autotuning Alpha 374 (Serial #1) i bought in 1974 which spoiled me for autotuning amps forever...   My first Solid State Amp was a PW-1 - which spoiled me for solid state amps forever... Nothing like QUIET, Instant On, Instant OFF, COOL Running Solid State Amps for operator comfort.

    Ultimately it depends how much $$$ you are prepared to spend.  Almost any amp will do something for you  (Life is far too SHORT for QRP)....

    Heatkits are long at the tooth but proven reliable IF they were asssembled by someone who knew what they were doing..The Ameritron Amps work.. their quality is questionable and I would not want to depend on one for a contest...  It's a toss up between the Alpha and ACOM.. Alpha is USA Made (?).. ACOM is a clone but less expensive..  The 500W Elecraft is cute but like a Smart Car.. why would anyone want to drive a small thing like that..  The PW-1 is getting pretty long at the tooth for a Solid State Amp... There are a few Yaesu Quadra's around.. good solid performer for a 20 year old design but **** interface...The current hottest AMP on the market is the SPE 1.3K... same features are the 2K but 60% of the power in by far the lightest and smallest package.. it is easily the favorite of DXpeditions..

    Dayton,. Being Dayton.. if you can wait until May.. who knows what 4A3O and Flex may announce....

  • Steve WS5WSteve WS5W Member ✭✭
    edited February 2016
    didn't SPE close their doors?
  • Roy LauferRoy Laufer Member ✭✭
    edited February 2016
    No, that was a U.S. distributor (the owner became sick and died, his daughters tried, unsuccessfully, to run the distributorship). Another U.S. distributor is alive and well and selling them as fast as he gets them.

    SPE in Italy is also very much alive and well and trying to deal with the incredible demand of the 1.3K-FA...
  • Walt - KZ1FWalt - KZ1F Member
    edited November 2016
    Why would anyone want to use the KPA-500?
    Because it cost $3000 not $11,000 and 650w is, i S units, real close to full legal limit. I never have an issue working dxpeditions on 5 bands or, for that matter, working 1/2 a planet away.  It runs on 120v.
  • Steve WS5WSteve WS5W Member ✭✭
    edited February 2016
    very good! I googled them and hit the dead one. I thought it was the Italian owner who died.

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