High SWR

Jim

Im looking for ideas or suggestions. I am running a 6400 connected to an Ameritron AL-80B amp connected to an LDG AT-1000 Pro 2 tuner connected to a Daiwa CN-901HP power/swr meter, which connects to a Hygain AV680 vertical antenna.  My 6400 does not have the internal tuner. My issue is that the 6400 shows the swr pegged, but the swr at the power/swr meter shows almost 1 to 1.5 after the tuner goes through its gyrations. Everytime I transmit, the tuner wants to go through a tuning cycle. I have eliminated (one at a time) all of the devices listed above, and Ive replaced all of the coax jumpers. Nothing changes. This same condition exists on all bands except 40 meters, which the radio shows a 1.75 to 1 swr and the tuner acts normally. Im at a loss as to what to try next. I would appreciate any ideas as to what to try next. Thanks in advance KC3KRZ

KD0RC

Neil D Friedman N3DF

Shouldn't the SWR meter go between the amp and the tuner rather than between the antenna and the tuner?

Homer1952

Bill -VA3WTB

Neil has a point. Your SWR meter right now is seeing the antenna SWR. But if you put the SWR meter behind the tuner, it will tell you the SWR that the tuner provides.

RoyS

Neil, unless Jim's post is a typo, I think you nailed it.

Bill -VA3WTB

So I would do this.

Radio> SWR meter> Amp> Tuner.

Geoff AB6BT

That will only tell you the SWR from the radio to the amp, not how well the amp is matched to the antenna.

Yes?

KD0RC

Yes, but that might be the problem.  If the amp is not providing a 50 ohm load to the exciter, Bill's set up will detect that issue.  Once resolved, I agree, the final point should be:
Radio - amp - SWR meter (assuming it can handle the power...) - tuner - antenna

Len

Bill -VA3WTB

KD0C, that would be correct, now he can see how everything is behind the tuner. But for tuning the in puts you use a dummy load on the amp and tune for max power. I don't think his amp has them,,but my AL 811 does for all bands.

Doug

Geoff AB6BT

I think this is the correct approach as well.

Perhaps the first step would be connect the radio directly to a 50 Ohm dummy load ave verify that there is a good match. 

If that looks good then proceed to the next step.

There may well be a problem with the amp input. If the SWR, measured between the radio and the amp with the amp connected to a dummy load of 50 Ohms, is high then you will have isolated the problem and can look a bit deeper as to the cause.

Jim

Thanks for the tips.  I will investigate and report back

N8AUM

RoyS

Jim

Bill -VA3WTB

What SWR do you have going directly to the Flex, bypassing everything,,work backwords till you find were the high SWR begins 

KI4P

at a 1.3 the flex should have never folded back on that, there usually good to upwards above 2 from what ive read.jmo!

RoyS

KI4P.
The threshold for SWR power foldback was set at 1.2 several years ago. After many complaints, the newer radios are able to handle a higher SWR so the software was changed to take advantage of the improvement. (at least that is what I understand)

Roy - W5TKZ 

KI4P

Wow! 1.2! That's crazy. Hadn't heard that one

Neil D Friedman N3DF

The 6400M/6600M manual says that software folds back the transmitter power if the reflected power exceeds 25 watts.  That's an SWR a lot higher than 1.3:1.

RoyS

Neil, you will get no argument from me on that one. I just referenced the original post from Jim that states "the 6400 shows the swr pegged" so no telling what the actual SWR is.

Cono A DelRosso

I have the exact same setup 6400M LDG AT1000PROII With the M-1000 Meter and the AL-80B AMP on 20m 14.290 the FLEX SWR shows 2.5 but the tuner shows me 1.5 but if I tune the AMP on the FLEX is a perfect match.

Bob Needleman