Using Linear Amp with Flex 6400M

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  • Updated 6 months ago
I have ordered a Flex 6400M and been reading the manual to get things ready for when it arrives.  I am trying to figure out which RCA connector on the back will key my linear amp.  It appears that it is either Connector 9, or any of TX1, 2 or 3.  It appears connector 9, which the manual does reference as being for a linear?  Please forgive the rather basic question but I just want to know how to connect the linear so that the rig will key it.  My linear is a Tokyo Hy-Power 1.2KFX so it requires me to manually tune the band.  So I just need to know which RCA connector on the 6400M will key the amp.  I am very impressed with the company, the product, and the user group, so hope this question is not to basic for all the knowledgeable people here.
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Roger J. Buffington

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Posted 6 months ago

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Doug

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Any of the rca jacks will key it. Just match up the jack you plug it into with the menu in the 6400M . I use #1 with my 6400M
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Roger J. Buffington

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OK, great.  That is kind of what I thought that the manual was saying, but wanted to be sure.  Thanks!
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Doug

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My pleasure Roger and I can assure you, you have a very pleasant experience ahead of you. Like a fellow ham I talk to about every day says "once you go Flex you won't go back".
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David Decoons wo2x, Elmer

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As Doug stated, TX1, TX2: or TX3. You need to enable the connector you use in settings/radio setup/transmit. Also if needed you can add TX Delay if your amp requires it.

I would suggest an ARB-704 amp keying buffer between radio and amp. Not needed but cheap insurance.

Dave wo2x
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Neil N4FN

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Dave WO2X has a great suggestion, the ARB-704 is a great safety. When I had a Yaesu FT2000 the techs suggested its use. The buffer works well.
Neil   N4FN
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Roger J. Buffington

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Thanks guys.  I used my FT1000MP without the buffer using this linear, but I still like the ARB-704 suggestion.  Really appreciate all the help.  Technically, I am a little rusty having been off the air the last 3 years.  I am looking into the availability of the ARB-704.  Hopefully my local HRO can help me.
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David Decoons wo2x, Elmer

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They should carry it. All you need is an RCA male to male to go from the ARB704 to TX1 on radio.

Enable TX1 in settings/radio settings/transmit.

Have fun and helping new users is why the Community is here.

Dave wo2x
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Roger J. Buffington

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I don't even have my Flex yet and I am already liking this community a lot!  Ordered the ARB704 and a couple of high grade RCA cables so it should be fine!  Thanks for all the great info.  Like I said, I am a little out of date and a little rusty technically.  (But thank God I remembered to renew my license last year!) 
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Greg - N8GD

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I always tell Hams to be sure to renew your license when it comes due, even if they're not active.  It only takes a few minutes to do online and costs nothing.  You never know when you might want to jump back in and become active again!  My son has renewed his license even though he is currently inactive with a demanding job, a growing family, and moving into a new house.
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Ron W4RDM

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I've used the K4POZ amplifier buffer on every amp I've had.

http://www.k4poz.com/keying/index.html
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Roger J. Buffington

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Out of curiosity, if I put an LP100A between the rig and the linear does that provide the same kind of buffering?  
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Doug - W5WTX

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The LPA-100A does not provide for a keying buffer.  It can be configured to provide a high SWR protection feature that will prevent operating your amplifier above a user defined SWR level.  The LPA-100A can sense high SWR much faster than I can read and mentally interpret a meter reading.  It also has an audible alarm which I personally like.  I believe the audible alarm can be turned off if you don't want it.


Putting the LPA-100A between the rig and linear will only sense the SWR as seen at the input of your amplifier and will not protect the amplifier.  To provide SWR protection / alarm for your amplifier, you will need to put the LPA-100A head on the output of your amplifier.

(Edited)
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Roger J. Buffington

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Thanks Doug.  Looks like I will be running the keying buffer and the LP100A.  I really appreciate the elmering from you and everyone else here.
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Mark Thomas

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Note the LP-100A would interrupt the amp keying line, causing hot-switching of the amplifier. Some amps such as the Elecraft KPA-500 specifically state this is acceptable, but for many amps keying or unkeying while still transmitting RF is bad news. Whether unkeying under RF is less evil than leaving the amp keyed into high-SWR is a matter of your judgement. Perhaps just relying on the built in amp protection might be safer for the amp.

I note Array Solutions sells an ALC-1 device which uses an adjustable switched ALC voltage to quickly and safely cut the Amplifier power output when triggered by high SWR detection from a device such as the LP-100A, to avoid the hot-switching problem of just interrupting the key-line. This struck me a good approach, and at least worth consideration.
-Mark  KC3DRE
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Roger J. Buffington

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I intend use the LP100A for measuring power and SWR, not to interrupt power if SWR is high.