Tuner problem

[918Oklahoma]

I run an IC-7200 coupled with a LDG IT-100 tuner. Lately I have been having a problem... When I tune up on a frequency, the tuner has no problem loading up. However, when I begin to transmit or enter a QSO, the tuning light will flash red 3 times and it loses tune, swr goes back up and output is reduced. What could be the cause of this? I tried running a brand new station ground thinking it could be RF getting into the tuner, but this didn't fix the problem. Keep in mind this is a fan dipole that i am tuning and for the most part it is tuned to frequency, I am simply using the tuner to trim up my match, so it is well within the tuners range. When I first got everything set up, I was not having this issue. Any ideas as to what the problem could be would be appreciated, thanks.

 

[222DBFL]

Check all your connections and refer to the owners manual as well. I would venture to say there is a trouble shooting tips page or some form or trouble shooting help in the manual. But other than that, check all your coax connections, and coax as well for pinches, loose fittings, and such. I've seen a connector come completely apart from moving around in the wind and weather. I know it sounds weird but it happens. The back end loose and the actual connector outer shell that tightens the connector to the SO239 was unscrewed all the way as well. And they were put on with pliers. At any rate, check your coax first. If you have a dummy load place it after the tuner at the antenna feedpoint and see what happens when you tune. If all else fails they do have a 2yr warranty. Might have to send it in. At any rate check all your coax, jumpers included, and at the feedpoint. Could be an issue that is not present until a load is present like when you modulate. Also could be too much of an impedance match, even though they state 800ohm cap. they also state to purchase the balun for certain long wire or random wires and ladder fed line. Hope you get it resolved. Good luck and hopefully someone has had this issue and can help as well. Hope all is well there.
73 and God Bless,
Sean

 

[RatsoW8]

I've noticed the same thing with my AT-600Pro. A close match seems to confuse the tuner. It will do what you described or kick into bypass mode. I start to transmit while it's showing bypass and it will start to tune again...some of the time. I'm not sure what the solution is.

 

[w9cll]

Had that same issue with my IT-100 and found it was a dead short in the antenna that was the problem. The balun went bad and once I replaced that everything worked as normal. Check the antenna first...

 

[wavrider]

1:1 current balun at the feed point??
Maybe CMC on coax,

 

[Road Squawker]

I run an IC-7200 coupled with a LDG IT-100 tuner... the tuning light will flash red 3 times and it loses tune, swr goes back up and output is reduced.... this is a fan dipole that i am tuning and for the most part it is tuned to frequency, I am simply using the tuner to trim up my match,....

something doesn't sound right, if the antenna actually is resonant, then why does the VSWR "go back up"??

before we go any further,... are you POSITIVE the BYPASS LED is not lighting up?


assuming you are using an ICOM cable,......

are you saying the RADIO is "folding back" the output power or the tuner is reducing the radios power during a tuning cycle?

if it is the radio, then the tuner can not find a setting to lower the VSWR to the setpoint,... check the antenna and feed line...... put the tuner in manual (bypass) , operate the rig and watch the VSWR

if you have an extra meter , put it after the tuner and observe it. it almost sounds like you have an intermittent/loose connection.

after you check a few items, then we can get into details about the quirks of these tuners.

 

[Road Squawker]

... A close match seems to confuse the tuner.. I start to transmit while it's showing bypass and it will start to tune again...some of the time. I'm not sure what the solution is.

these tuner actually have MORE that one "automatic" mode

"FULL" auto... tunes EVERY time RF is present AND swr exceeds the setpoint.

"SEMI" auto... tunes only when TUNE button is cycled. (to me , this sounds like "manual" , but the LDG manual is poorly written).

you can adjust the VSWR "setpoint" so the tuner doesn't try to tune as often.

 

[RatsoW8]

Good info RS. Admittedly I only skimmed through the manual when I got the tuner and then hooked the tuner back up after 6 months of non use without re-reading it. Goes to prove once again..If all else fails, read the manual.

 

[918Oklahoma]

these tuner actually have MORE that one "automatic" mode

"FULL" auto... tunes EVERY time RF is present AND swr exceeds the setpoint.

"SEMI" auto... tunes only when TUNE button is cycled. (to me , this sounds like "manual" , but the LDG manual is poorly written).

you can adjust the VSWR "setpoint" so the tuner doesn't try to tune as often.

It's a bit confusing determining what mode is in, that's one of my complaints about it.... I've read the manual front to back several times, nothing in it addresses my issue... Any idea how to adjust the swr thresh hold? The manual doesn't mention it.


It has done this with 2 different Antennas now. Towards the end of the time I had my g5rv jr. Up, it started having this issue.

What I mean about the swr going back up... In my operating range on 40m I get a reading of 1.8-2.0 before a tuning cycle... After hitting the tune button on the radio, it will drop to 1.1 on the frequency I tune for. Then when I transmit i can watch my Smeter showing I have a strong signal until the tuner makes a clicking sound and then the red tuning light flashes a few times and my S meter shows a weaker transmitting signal and when I check the swr again, it's gone back up to 1.8 like before the tuning cycle.

When it happens during a QSO my contact complains about my signal dropping off and I lose them usually. So I assume it is the radio reducing power after the tuner loses match.

Unfortunately I have no test gear, only the swr meter built into the radio.

 

[Mudfoot]

I've noticed this problem with a couple autotuners in the past, both MFJ and LDG models. I can't recall, but I remember reading an article somewhere where the issue was explained in detail. I believe LDG posted an response as well.

Call LDG, they'll give u the exact poop as to why, along with a resolution.

 

[w9cll]

To further clarify what the issue was with mine, because the balun was shorting out I was getting an extreme amount of RF on the coax back into the shack. This was getting into the tuner, if I kept the rf under 20w all was good, over that and the tuner would kick out of tune just as your indicated here.

 

[Road Squawker]

... when I begin to transmit or enter a QSO, the tuning light will flash red 3 times and it loses tune, swr goes back up and output is reduced. What could be the cause of this?.

3 flashes from the tuning led means the tuner has shifted to BYPASS mode,(swr led should not be lit. ( yeah, that seems backwards, but,... the swr led is lit when there is an acceptable vswr.)

...hitting the tune button on the radio, it will drop to 1.1 on the frequency I tune for. Then when I transmit i can watch my Smeter showing I have a strong signal until the tuner makes a clicking sound and then the red tuning light flashes a few times and my S meter shows a weaker transmitting signal and when I check the swr again, it's gone back up to 1.8 like before the tuning cycle...
Unfortunately I have no test gear, only the swr meter built into the radio.

Bottom line: the tuner can not find an acceptable VSWR so it is defaulting to the safe mode (bypass).

at first I suspected RF affecting the tuner,....... but,...... because the radio is folding back the output power AFTER the tuner is in bypass, that tells me that you actually DO have an unacceptable VSWR being presented to the radio.

the question is, does the radio return to, and remain at, full output power after the tuner is bypassed?

if yes, then the tuner is the problem. (actual tuner malfunction/RF affecting the tuner)
if no, then the feedline/antenna is the problem

take the tuner out of the circuit and investigate.

BTW, LDG clearly mentions limitations on input power levels for this model,..... 35 watts MAX continuous duty.

 

[918Oklahoma]

I think im just going to take it down and tune it. It's resonant lower in the bands on both 20 and 40 so i think i'll trim it up and just not use the tuner.

 

[Mudfoot]

MFJ had me send mine back for repair. I cannot remember what was wrong, but it worked fine afterwards.