6300 Antenna Tuner Problems

Randall Steffens II

Hi Everyone,

I have the Flex 6300, and am experiencing problems with the internal tuner being unable to tune my antenna on any band.  I have a center fed dipole, both arms 30 feet long (the largest I could fit in my yard) about about 30 feet above ground, fed with with 450 ohm ladder line.  I do not have a balun attached yet. I'm also using the dogparkSDR client for MacOS.

What would be your suggestions for getting this thing to tune my antenna?  It won't tune on any band period!

Thanks,
Randy Steffens

Bill -VA3WTB

Try and delete the tune memorys...  right click on MEM and delete.

Jay Nation

Randall
How long is your 450 ohm feedline?

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Bill -VA3WTB

I am making the assumption your antenna is tunable? it already has a good SWR?

Mike-VA3MW

2 things Make sure your tune power is not set to Zero Can you test into a dummy load ? Mike

Jim Gilliam

An investment in an antenna analyzer would help. It will tell you what the impedance of the antenna is at various frequencies. It could be the impedance is out of range than what the antenna tuner is capable of tuning. One can change the impedance looking into the antenna by varying the feed line length but what might mitigate one band could easily aggravate another. Non resonant antennas can be tricky for a tuner that is only capable of tuning in a range no greater than a 3:1 SWR.


Jim, K6QE

Jay Nation

Randall

You might also need a 1:1 current balun at the radio end of the feedline.

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Randall Steffens II

Thank you!  Feed line length is about 40 feet.  I'll be ordering a balun shortly, and plan to re-test with it.  I would have thought the antenna would be tunable on *some* band without a balun!  But this is my first multi-band dipole, so I'm inexperienced with how these things perform.  I've only ever used verticals previously. 

Randall Steffens II

Thanks!  I'll try clearing the memories. I thought the 6300 didn't have memories, but I was probably wrong!  I just put up as much wire as my yard could fit and didn't try to prune to any specific frequency since I wanted to use it as a multi band and let the tuner do the work!

Randall Steffens II

Tune power is 10 watts.  I don't have a dummy load yet unfortunately...

Randall Steffens II

Interesting. That's probably the issue I'm having since I didn't prune my antenna to any particular frequency. I just put up as much wire as I could fit in my yard and planned to let the tuner deal with matching.  I didn't realize the internal tuner couldn't handle anything about 3:1.  My SWR is above that on every band. 

I really need an antenna analyzer. The RigExpert AA-30.ZERO on Amazon is a DIY solution I've been eyeing for a few months.  Inexpensive, but with a little rigging it seems to perform pretty well!

Jim Gilliam

Since the antenna is inherently balanced one does not need a BALUN at the junctions of the antenna and the balanced feed line. The output of the transmitter has to be balanced. The Flex is unbalanced. I would highly recommend that an external balanced tuner be connected between the feedline and the Flex. Also, one could try hooking the BALUN at the output of the transmitter and connecting the balanced end to the feedline.

Randall Steffens II

Thanks Jim.  Would you suggest a manual balanced tuner in this case or an autotuner like the MFJ 993B? 
Randy

K8AC

Balanced feedline, how are you connecting it to the Flex??  I'd be amazed if the internal tuner (ANY internal tuner on ANY rig) were able to provide a match for that antenna.  You didn't mention which band(s) you were operating on, but you can pretty much forget using the antenna on 80 meters.  You really need to be thinking about an external tuner even if you were to use a balun to allow you to provide a coax connection to the 6300.  It may be possible by playing with the feedline length to achieve a match on one band with the internal tuner, but chances of achieving a match on other bands is just about zero.  External tuners generally have an impedance matching range far, far greater than any internal tuner. 

73, K8AC 

Bill W2PKY

Look up G5RV and ZS6BKW antenna projects. The length of the arms and open wire line are critical to having a SWR low enough for the 6300 to tune. The length of the coax may need adjustment as well. GL

Jay Nation

Randall

Check out https://www.w5dxp.com/ for some ideas for space limited antenna possibilities.

and

http://www.w5dxp.com/goodbad/goodbad.htm

Read over his webpage above about how to figure out the proper feedline length for a 60' doublet. If you have MS Office you can download and run the Excel spreadsheet version of  IMAXGRAF.xlsx  and it will calculate workable feedline lengths you can try.

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Randall Steffens II

I see.  Very interesting.  Thank you gentlemen.  It looks like I had completely unrealistic expectations for what the internal tuner could do with the antenna. I will look into an external tuner and/or modify my antenna.

Randall Steffens II

Thanks it looks like I had completely unrealistic expectations for what the internal tuner could do.  I just soldered the end of the balanced feed line to an SO-239 and used a foot of coax with PL259's on both ends to connect to the radio.

Randall Steffens II

Thank you very much!  I'll check that site out now.

Jay Nation

Randall 

I use a ZS6BKW as my primary antenna, its @ 93 feet long though, so may not work at your QTH. 
It works most bands 40m and up, using the internal tuner, with a better than 1.5:1 match. however "most bands" doesn't include, 30m and 15m. 

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bahillen

If you have the dipole configuration you can make it longer by just adding wire to the ends and dropping down or to another direction. If you tie the two ends of the ladder line together that will give you a configuration that is like a vertical. Find a friend with an antenna bridge and see where you are starting from. Look up information on a fan dipole as it is feed with 50 ohm coax. I have a fan dipole your size that covers 40-10m. If you need a few feet for 40 let the wire hang straight down. Resonance was not good on 15m but added two drooping wires on 40m element at 10 ft from center and 20 inches long. 73 Bill W9JJB

Mike-VA3MW

Good morning Randall

I think that every ham needs to add a dummy load to their Christmas list.     Seriously, if you are just getting into HF it is one of the best tools for helping to eliminate HF problems.  

Like other have mentioned, the next thing to add to your tool box is some sort of antenna analyzer like the Rigexpert AA-30 which is great value.   

The antenna tuner in the radio is good for about a 3:1 SWR (sometimes better).  

Let us know how you make out.

Mike

Randall Steffens II

Thank you Jay!  I'll look into that antenna.  Sounds promising!

Randall Steffens II

Thanks Bill,
Very interesting regarding the fan dipole.  I'll look into that.  I'm not experienced in the HF frequencies so all this advice has been so useful!

Thank you very much everyone!