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Author Topic: Problem with MFJ-5124Y interface betw 993B tuner and FT-897D  (Read 4412 times)
N5BLP
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Posts: 13




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« on: February 01, 2011, 02:46:17 PM »

With the MFJ993B tuner connected to my FT-897D using the MFJ-5124Y interface, everything on the HF side of the radio works just fine and the tuner works great.  The problem is that if you try to operate using the VHF/UHF side of the radio (i.e. on 2m or 70cm using either VFO) the radio won't transmit but a watt or two no matter what you have set.

I've gone back and forth with MFJ on this.  First they tried to say is was bad grounding.  Then one of their beta testers suggested grounding one of the pins that was apparently not being used.  As far as I know nothing came of that, and they are now in the process of sending me a replacement cable for the interface, which I have little hope will solve the problem since they still haven't told me what the cause is.

Does anyone out there operate this particular configuration, and if so, have you experienced the same problem?  I suspect when they designed this interface, they tested the heck out of the HF side and never checked to see if the VHF side of the radio still worked.

Bart/N5BLP
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AD5X
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Posts: 1426




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« Reply #1 on: February 01, 2011, 05:14:31 PM »

Since they're sending you a new cable, I bet they figured it out.  I had an FT-990 and a FT-1000MKV and it looks like the same type interface is used on the FT897.  On the big radios, there is a microswitch on the Band Data connector that grounds the TX Inhibit input unless a connector is plugged in.  The FT-897 connector also has a TX Inhibit pin and I bet it works the same way.  I see in the MFJ instruction manual that the tuner grounds this TX Inhibit piin, which permits the FT-897 to transmit (this input is normally used with amplifiers that have an output that inhibits the transceiver until the amplifier relays have operated).  Anyway, when you are using VHF or UHF outputs on the FT-897 and the autotuner isn't used (since it is HF only), the autotuner won't ground the TX Inhibit pin so the transmitter won't transmit.  I bet that MFJ just shorted this pin all the time in their new cable rather then let the tuner control it.

Phil - AD5X
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N5BLP
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Posts: 13




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« Reply #2 on: February 04, 2011, 01:37:32 PM »

Since they're sending you a new cable, I bet they figured it out.  I had an FT-990 and a FT-1000MKV and it looks like the same type interface is used on the FT897.  On the big radios, there is a microswitch on the Band Data connector that grounds the TX Inhibit input unless a connector is plugged in.  The FT-897 connector also has a TX Inhibit pin and I bet it works the same way.  I see in the MFJ instruction manual that the tuner grounds this TX Inhibit piin, which permits the FT-897 to transmit (this input is normally used with amplifiers that have an output that inhibits the transceiver until the amplifier relays have operated).  Anyway, when you are using VHF or UHF outputs on the FT-897 and the autotuner isn't used (since it is HF only), the autotuner won't ground the TX Inhibit pin so the transmitter won't transmit.  I bet that MFJ just shorted this pin all the time in their new cable rather then let the tuner control it.

Phil - AD5X

Phil:

I follow what your saying, and it sounds like what their beta tester was saying.  One thing that doesn't quite connect is that the VHF side IS transmitting, it's just putting out almost no power.  The power meter (what there is of one) doesn't deflect, but nearby stations can still get me, just very poorly.  So something's going out, just at very low power, like one or two watts.  Maybe the TX inhibit circuit in the radio just inhibits the final stage amp.

If that's the fix, it would be nice if they admitted it.  They didn't say this new cable was any different than the one I have.

Bart/N5BLP
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N5BLP
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Posts: 13




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« Reply #3 on: February 13, 2011, 01:56:48 PM »

Since they're sending you a new cable, I bet they figured it out....... 

Phil - AD5X

Update.  They didn't figure it out.  They just sent me another of the same old interface, new in the box.  I sent in my 8th or 9th trouble ticket informing them.  This is getting old.  I don't think they'll get too much business from me in the future.
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AD5X
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Posts: 1426




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« Reply #4 on: February 14, 2011, 04:09:08 AM »

I don't have an FT-897, but I've used MFJ autotuners with a FT-990 and MKV, and IC-706/7000.  All work great.  I see that the FT-897 has a menu (20) that sets the type of port to CAT, LINEAR or TUNER.  I'm guessing it should be set to CAT, but maybe it should be set to TUNER.  Have you tried both?  And is this a setting per band?  Can't tell from the manual.  I.e., if you are on VHF or UHF or HF, does Menu 20 change when you change bands?  If so, then you need to set it for whatever works on the particular band.

Phil - AD5X
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N5BLP
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Posts: 13




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« Reply #5 on: February 14, 2011, 06:14:47 AM »

I don't have an FT-897, but I've used MFJ autotuners with a FT-990 and MKV, and IC-706/7000.  All work great.  I see that the FT-897 has a menu (20) that sets the type of port to CAT, LINEAR or TUNER.  I'm guessing it should be set to CAT, but maybe it should be set to TUNER.  Have you tried both?  And is this a setting per band?  Can't tell from the manual.  I.e., if you are on VHF or UHF or HF, does Menu 20 change when you change bands?  If so, then you need to set it for whatever works on the particular band.

Phil - AD5X
Phil:

Both the Yaesu and MFJ instructions tell you to set it to TUNER.  It's not a setting per band, but for all the HF bands.  It's ignored on the higher bands (when the tuner is active, TUNR is displayed in upper case, when you go to VHF it is displayed as "tunr" in lower case to tell you it's not being used).  I even tried de-selecting it and it doesn't solve the problem.  As long as the CAT cable from the MFJ-5124Y is plugged in, regardless of menu settings, the problem exists.

Here's another tidbit.  Before getting the MFJ tuner, I was using the Yaesu FC-30 bolt-on tuner.  This tuner connects through the CAT plug the same way, and the menu settings are the same.  The problem does not exist when using this tuner (undoubtedly because Yaesu handles the TX inhibit correctly).  I still use this tuner with my Buddipole when operating portable.  It's only problem is that it is a narrow range tuner.  I needed a more broad range tuner at home.

Bart/N5BLP
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AD5X
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Posts: 1426




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« Reply #6 on: February 14, 2011, 06:57:41 AM »

OK - When set to TUNER (or LINEAR) the TX INH input is active.  So grounding this pin all the time really should solve your problem.  In the MFJ tuner instruction book, this line is controlled by the tuner.  I don't think it is ever necessary to control TX INH with the tuner.  I bet you can just open up your tuner and find this line.  Then cut it, and ground it where it leaves the tuner. 

Phil - AD5X
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N5BLP
Member

Posts: 13




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« Reply #7 on: February 14, 2011, 01:58:32 PM »

OK - When set to TUNER (or LINEAR) the TX INH input is active.  So grounding this pin all the time really should solve your problem.  In the MFJ tuner instruction book, this line is controlled by the tuner.  I don't think it is ever necessary to control TX INH with the tuner.  I bet you can just open up your tuner and find this line.  Then cut it, and ground it where it leaves the tuner. 

Phil - AD5X

That would probably work, but would also certainly void the warranty on the tuner.  Plus, it lets MFJ off the hook.  I think it's incumbent upon them to redesign the interface so it works properly.  I will keep that in mind though, if it gets to the point where the tuner is out of warranty and I get tired of disconnecting it to use the VHF side of the radio.  You're a lot more up to speed on this stuff than I am, so I really appreciate all your input.  (Makes me wonder why they seem to be having so much trouble figuring it out.)
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AD5X
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Posts: 1426




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« Reply #8 on: February 15, 2011, 12:07:50 PM »

Menu 85 should also be set for TUNER.  Go ahead and short to ground pin 7 (TX INH) of the RJ45 connector inside the MFJ-5124Y.  It won't hurt anything.  If it doesn't work, you can just remove the short.

Phil - AD5X
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N5BLP
Member

Posts: 13




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« Reply #9 on: February 15, 2011, 02:59:15 PM »

Menu 85 should also be set for TUNER.  Go ahead and short to ground pin 7 (TX INH) of the RJ45 connector inside the MFJ-5124Y.  It won't hurt anything.  If it doesn't work, you can just remove the short.

Phil - AD5X

MFJ finally got back to me today and owned up to the problem.  They sent me instructions for shorting the pins as you described, so off I go.  Mucho thanko again.
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KE5DFK
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Posts: 28




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« Reply #10 on: February 25, 2011, 07:30:16 AM »

When using VHF/ UHF are you turning off the tuner?  When the antenna is connected to ANT 1 on the tuner and turned off it is a direct bypass to the antenna, ANT2 will not bypass to the antenna.  If the tuner is turned on it will send the VHF / UHF signal into an HF tuner.  Probably not a good idea.  Not sure what your interface does.

I run the same tuner on a TS-480HX and I run direct from radio to tuner without any interface.  When set to auto the tuner tunes when you key up.  On the HX model the PF button is configured by menu to be the tuner input at 10w. 

Hope this helps you.

Carlos
KE5DFK
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N5BLP
Member

Posts: 13




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« Reply #11 on: February 25, 2011, 08:18:49 AM »

When using VHF/ UHF are you turning off the tuner?  When the antenna is connected to ANT 1 on the tuner and turned off it is a direct bypass to the antenna, ANT2 will not bypass to the antenna.  If the tuner is turned on it will send the VHF / UHF signal into an HF tuner.  Probably not a good idea.  Not sure what your interface does.

Carlos
KE5DFK

The VHF/UHF antenna and the HF antenna on the radio have different connectors.  The HF connector goes to the tuner and the VHF/UHF is connected directly to the antenna.  Two completely separate systems.  The tuner stays turned on, but when you're on any band above 50 MHz, the radio ignores it and uses the other antenna. 

Grounding pin 7 solves the problem.
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