6300 - Planning to add ATU

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I am going to add an ATU to my 6300.
I use an Optibeam OB5-9 for bands between 10 an 20 and an homebrew linear loaded dipole for bans 30, 40 and 80 feeded with windowed 450 Ohm line and 4:1 balun.
I read about limited impedance range of the 6300 internal ATU and I am wondering if it could match my lineard loaded dipole.
I measured the following impedance :

F0=10.120 --- R=7  X=-14   Z=16

F0=7.050 --- R=64  X=35   Z=73

F0=7.150 --- R=60  X=4.4   Z=60

F0=3.550 --- R=13  X=0,5   Z=12

F0=3.650 --- R=10.7  X=21   Z=24 

F0=3.750 --- R=13  X=41   Z=43

Can I go with internal atu or is it better an external one (like LDG or similar)?

 73' Enzo
iw7dmh
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IW7DMH, Enzo

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Posted 3 years ago

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Steve W6SDM

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I would consider an external ATU so that if you want to add an amplifier later, you can do that.  I have used the KAT500 from Elecraft.  When I added my KPA500 amp, it virtually turned the 6300 into a 500  watt transceiver. I very rarely have to do anything when switching bands - even when switching antennas too.

Make sure whatever ATU you buy is rated for whatever amp you would eventually use.

Of course, if you go with the internal amp, you can always bypass it and use an external one behind your amp. 
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KD8TVB

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Interested in the KAT500 from Elecraft - do you use the auto sensing of RF? Any other thoughts? I have a tokyo hy-power 1.2, but has a band switch, kind of a bummer...

Thanks in advance
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Mark Erbaugh

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I use the KAT500 with a Flex 6300. I use the auto RF sense. I use the TUNE button in SSDR.
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Steve W6SDM

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Yes, I use auto RF sensing.  No problems at all with it.  You will find a lot of Flex/Elecraft combinations out there.  The equipment works good together and looks good together.
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KD8TVB

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I have my 6300 in a tripp lite enclosed rack, be good to have all of it together in rack... Any pics Steve?
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Dave - W6OVP

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My old LDG Z-11 Pro works just fine with the 6300. No plans to change, but have a 600W LDG ready if an amp is added.
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IW7DMH, Enzo

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Can you tell me if you use it in full tune mode, and if you have to use some tricks with your Flex?
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Dave - W6OVP

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I accept the FLEX Tune defaults and just click on TUNE each time I change bands. Otherwise it's mostly 'invisible'.
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Norm - W7CK

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I have the KAT500 and KPA500.  Like others, I also use autosensing and it works fairly well.  While I like the combination for general use, I would NOT recommend the KPA500 if your passion includes any of the common digital modes.  The KAP500 gets quite warm fairly fast and the darn fan ramps up in speed to the point it sounds like a jet engine sitting in the shack.  Obnoxious comes to mind.  It becomes so loud, I have moved it as far away as possible.  My wife can hear it from just about any room in the house. For SSB or CW it seems to do a fine job, for anything else it just gets too darn loud.

What's up with all the radio and amplifier manufactures skimping on heat sinks and instead putting in these crappy little fans!  What ever happened to the nice heat sink across the top or back of the rig that actually dissipates heat naturally?  All the fans do is create a bunch of noise and sucks a bunch of dust through the equipment!

Sorry for the rant..... I'll go away now.

P.S.  Go with an external tuner that can give you a good 10:1.  It will have RF sensing and It will be much more versatile than an internal one.  It will have tons of memories that work NOW and you can program it to use a particular antenna port based upon the band in use.  It will even work with your backup rig if you ever decided to put it on the bench.

(Edited)
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Wayne Brown

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Enzo:

I am just getting going with my Flex 6300 so don’t have much experience to draw on yet.  However, here is what I have seen so far:   My primary antenna is a 6-BTV 23 ft trapped vertical that is resonate on 80 meters at 3.525 mhz with the 6300 showing swr at 1.2 to 1.  As I go up in frequency the swr reaches top of the scale, 3 to 1, at 3.573, not unexpected with no tuner.  The ATU tunes it to 1.2 to 1 across the enter 80/75 bands to 4.0 mhz, so the 6300 is happy.  I used it to drive my AL-811H to work K1N on 75 meters SSB .  I am not versed in antenna impedance matching theory, so I hesitate to comment on your specific environment, but I’m glad I purchased the ATU. 

Hope that helps.

73, Wayne, N4FP