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Author Topic: 60 meter transmission problem using FT-950, MFJ-998 Tuner shows freq of 2.666mhz  (Read 2045 times)
K2CMH
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Posts: 278




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« on: December 19, 2011, 06:00:32 AM »

I have an FT-950 and MFJ-998 tuner. I was attempting to transmit on 60m with a dial frequency of 5.3665. When I started the tuning cycle, the tuner displayed a frequency of 2.6666, not the expected 5.3665, of course it did not attempt to tune since that freq is outside of the amateur bands.  The 998 showed a power output of 20 watts which was also confirmed by looking at the power out meter on the rig.  I tested the tuner on the other bands and it worked fine, just like it has been since I have owned it.  I have check the firmware revision on both the tuner and the rig and they are both up to date.  Has anyone seen this behavior before or have any ideas on what I can check to help troubleshoot.  I am going to call mfj, but I figured I would get some feedback here before wasting an hour of my life on hold that I will never get back.

Thanks,
Carlton
K2CMH
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KG4RUL
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« Reply #1 on: December 19, 2011, 08:50:14 AM »

How much power are you using while tuning?
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AD5X
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« Reply #2 on: December 19, 2011, 08:53:44 AM »

What antenna are you trying to tune?  And what is the untuned SWR?  If the untuned SWR is real high, the tuner may not be getting enough power to reliably detect frequency. 

Phil - AD5X
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K2CMH
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Posts: 278




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« Reply #3 on: December 19, 2011, 10:00:17 AM »

That particular tuner recommends around 20 watts or so, I tried both 20 and 25.  The tuner will tell you if you are not using enough power to tune, likewise, it will also tell you if you are using too much, which I believe is around 125 watts.  However, I want to reiterate, the problem is not that the tuner won't tune, it is that the tuner is reporting a grossly inaccurate frequency reading while trying to tune or just transmitting in general.  The radio is transmitting on 5.3665mhz but the tuner is reporting it as 2.666mhz, and as I mentioned, the tuner works fine on other bands and does not exhibit this bizarre behavior.  The antenna is the DX Engineering 43' vertical, but I fail to see how antenna choice could be causing the tuner to be returning such out of the ball park readings for what it thinks is the frequency given that enough power is being applied for the tuner to 'see' it.
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WA3SKN
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« Reply #4 on: December 19, 2011, 10:43:33 AM »

What happens when you use a dummy load?

-Mike.
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K2CMH
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Posts: 278




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« Reply #5 on: December 19, 2011, 11:03:06 AM »

>What happens when you use a dummy load?

Good question, I will try that tonight and post the results.  Someone else also asked what the swr was,  I will make a note of that and post that as well tonight.

Carlton
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NR4C
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« Reply #6 on: December 19, 2011, 11:16:18 AM »

It's odd that the tuner is reporting half the frequency.  Try more power, like 30-40 watts.

...bill   nr4c
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AA4HA
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« Reply #7 on: December 20, 2011, 06:41:41 AM »

It's odd that the tuner is reporting half the frequency.  Try more power, like 30-40 watts.

...bill   nr4c

I picked up on that as well. When you multiply the frequency by 2 you get really close to his actual transmitting frequency.

I bet the tuner found a resonant spot and is happy with it. Maybe the tuner is not used to the idea of the 60 meter band.

You are probably in some form or state of being tuned, again, it depends upon the antenna type as some types may be resonant at 60,30,15 and 120 meters. Just like how we have a relationship with 160,80,40,20,10 meters.
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Ms. Tisha Hayes, AA4HA
Lookout Mountain, Alabama
K2CMH
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Posts: 278




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« Reply #8 on: December 20, 2011, 02:05:43 PM »

Well it turns out the problem was not enough power to the tuner.  However, this particular tuner is supposed to give you a warning message when it needs more power to tune (I have seen it do this, so I know it does), but for some reason in this case it did not, it just gave the erroneous readings.

Thank you all for your suggestions and have a Merry Christmas.

Carlton
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