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Message |
    
Bob_p
Advanced Member
Username: Bob_p
Post Number: 550
Registered: 7-2004
| | Posted on Thursday, December 02, 2004 - 8:36 pm: | 
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Tech 833 I just bought a Kenwood TS 480HX and have been planning on buying a G5RV to use for awhile until I can afford a decent muti-band HF antenna.
My Question is after playing around with the I-Max and a MFJ-949E antenna tuner and can tune 17 to 40 meters with a flat 1.1.1 SWR. It doesn't even need the tuner on 15 meters, and at 17 meters I get a usable SWR without the tuner. But just to be safe I've used the tuner just to be sure.
Now I've talked on 15 and 17 meters and the I-Max seems to do pretty well but I have to wonder if it's safe to use the antenna on 17, 20 and 40 meters?
Your help will be greatly appreciated as always
Bob
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Tech833
Moderator
Username: Tech833
Post Number: 903
Registered: 8-2002
| | Posted on Friday, December 03, 2004 - 3:14 pm: |
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Hi Bob.
If your tuner tunes it and your power does not exceed 100 watts or so, then it is perfectly safe.
On 40 meters, the Imax will have a VERY low feedpoint impedance, so a tuner is vital. The performance will be poor but useable. |
Bob_p
Advanced Member
Username: Bob_p
Post Number: 551
Registered: 7-2004
| | Posted on Friday, December 03, 2004 - 3:47 pm: |
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Thanks Paul, my radio does 200 watts so would it be safe to use the 200 watts on 17 and 20 meters? or should I keep it down to 100 watts on those two as well?
I actually get a moderate but usable SWR on 17 meters, but have been using the tuner just to be sure it's not going to cause any problems.
Thank you very much and I doubt that you really know how much help you've been to myself and others on the board.
Thanks again
Bob |
Bob_p
Advanced Member
Username: Bob_p
Post Number: 552
Registered: 7-2004
| | Posted on Friday, December 03, 2004 - 6:24 pm: |
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I'm sorry I need to clarify something. When I said a moderate SWR on 17 meters. I'm getting a 1.5.1 or under without the tuner, so I guess that's actually a good SWR, but of course with the tuner I can get it flat. In this case on 17 meters with an SWR of 1.5.1 I am guessing that I could run all 200 watts without the tuner, but I am being cautious.
By the way the MFJ 949 shows an SWR of 1.3.1 without the tuner and the radio shows just a hair under 1.5.1.
On 20 meters I need the tuner to get a usable SWR but I can still get a 1.1.1 with no problem, but there is a lot of white noise. So I guess I need to keeep it at or under 100 watts on 20 meters.
Sorry to drag this out, but after I looked at my last posts I realized I didn't make myself clear, and the Kenwood being my first HF rig, I want to know that I'm not going to create any problems or hurt the radio.
Again thank you in advance
Bob
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Tech833
Moderator
Username: Tech833
Post Number: 906
Registered: 8-2002
| | Posted on Saturday, December 04, 2004 - 2:50 pm: |
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Hi Bob.
Running 200 watts PEP will not be a problem either. Especially on 17m. You should be able to run up to full legal power on 17 with no trouble.
What you are trying to avoid is getting a voltage potential in the tuning network high enough to arc across windings or connections and leave a carbon trace. |
Bob_p
Advanced Member
Username: Bob_p
Post Number: 553
Registered: 7-2004
| | Posted on Saturday, December 04, 2004 - 7:02 pm: |
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Thanks Paul I'll plan on using up to 200 watts on 10 through 17 meters, and will probably run less on 20 and 40 meters. I'm not sure if I want to even run the radio on 40 meters because I've heard that even though the I-Max will tune on 40 meters it is not very effective.
Thank you very much for your patience and assistance
Bob
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