MFJ-949E Tuner with Comet SBB-5
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| Nov 6th 2014, 17:29 | |
AF9UTotal Topics: 0 Total Posts: 0 |
Hello, I'm brand new to antenna tuners. But I'd like to test this new tuner against a somewhat known result. Right now when I key up on a quiet 2 meter frequency I getting a really high SWR, much higher than I would expect. So I think I have something set wrong and I'm hoping for some help doing this for the first time. So here is what I have: Radio - Yaesu 857-D, I have RF power dialed down to 5 watts for now so I don't blow anything up. Antenna - Comet SBB-5 (mag mount) - antenna is stuck to a metal pan so that it works (it works great when connected directly to the radio) Tuner - MFJ-949E Here is how I have everything connected: Antenna is plugged into Coax 1 on back of antenna tuner. Tuner "transmitter" port is connected to my 2 meter antenna connection on the radio with a short coax antenna tuner cable. On the Antenna Tuner I have: Antenna Selector set to TUNED - COAX 1 Transmitter - variable (I have been try to adjust these to a low SWR) Inductor - Set to I Antenna - variable Meter is set to the 300W setting (button pushed in) And Peak/AVG is set to Peak (button pushed in) Given all that, shouldn't I expect my forward needle to be somewhere close to 5 and my reflected needle to be somewhere between 1 and 1.1? What I am seeing is my power (when Inductor is set to I) is about 5, but my reflected is like 1.4 or 1.5. If I set my meter to 30W my reflected needle is up by infinity. Thoughts? I appreciate any help I can get. 73, Drennen AF9U |
| Nov 7th 2014, 13:44 | |
WB1GCMSuper Moderator Total Topics: 0 Total Posts: 0 |
Dear Drennen, Check the specification of the MFJ-949E. You will see the tuner is designed to operate between 1.8 and 30 MHz. It will not work on 2 meters. A good rule of thumb is to use a resonant antenna, when possible, so no antenna tuner is needed. There is no need to add a tuner if your mag mount antenna works well without one. I used to use the same type of antenna when I lived in an apartment back in the 80's. I had a Larsen mag mount on top of a well seasoned baking pan. The outfit was placed on a flat roof, about 10 feet away from my shack window. It worked great. Have fun, 73, Bob Allison WB1GCM ARRL Senior Test Engineer |
| Nov 11th 2014, 15:43 | |
AF9UTotal Topics: 0 Total Posts: 0 |
Thank you Bob, I appreciate the information. I thought I had read it would tune almost any antenna, but I obviously misunderstood. Thank you for clearing this up for me. Take care, 73, Drennen |
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