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G’day all,
I have been a reader and lurker in this group for a while and this is my debut post!

After a good few years of use and abuse my 817 has decided to give me a high VSWR reading on the 2m band.?

I have searched through the group posts for ideas and tried a few suggestions including a full reset to no avail.?

I have tried the rig on both front and rear antenna jacks and on 3 different antennas (all dual/tri band and all work fine on 70cm and 6m) with the same result.
It is not only indicating a high VSWR on the meter (occasionally displays text “high VSWR”) but is folding back the tx power so I can’t even trigger the local (60 over 9 normally) repeater.
When I did the reset I did disconnect all power and battery prior to the reset (home+power) as this was one of the suggestions I found.?

Does anyone have an insight into the problem?
Any quick fixes?
Any pointers on where to start trouble shooting? ?I had a quick read of the circuit description and have one area to check which is the 2 diodes off the directional coupler for 2M as it seems to be the only point that is not common to the other bands. Any thoughts?

I have not had time to rip the covers off yet so have not done any actual testing under the bonnet so to speak.
Oh and just to be clear it still receives as well as always on 2M on all antennas tested.
I am seeking the technical wisdom of the 817 hive to guide me

Cheers
Col
VK6ACT

On 2022-03-04 19:57, Colin Trueman wrote:

G'day all,
I have been a reader and lurker in this group for a while and this is
my debut post!
After a good few years of use and abuse my 817 has decided to give me
a high VSWR reading on the 2m band.

snips

Any pointers on where to start trouble shooting?

Cheers
Col
VK6ACT

Hullo Col,

Sri to hear this.

I re-read to ensure antennas were used for all tests.

Useful to hear it appears there is fold back/protection going on. The PA is essentially all-band, so no mysteries with respect to it. (I have the replacement board. Must put in. sigh.)

My limited offer is based on issues with weird antenna effects on my apt./flat balcony, and while mobile. In my tests I've sometimes remembered the get the antennas out of the equation by using a dummy load and to try it at each antenna connection on the radio.

I don't think it was mentioned which modes were used. CW for all tests? FM? Tone on SSB, a data mode signal?

I noted your choice to remove cables for the reset. FB.

Do you use any data modes? Was the cabling for that reconnected at test time?

Perhaps try testing, with a dummy load, without the mic., and data/control cables (if any.)

Has the power lead any protection against RFI? Is it the "right" length to be so affected?

I've a crap 6m in-the-window set-up with my FT-857D. In spite of a (mutter mutter, sort of) counterpoise for the back-of-set vertical, I've noted the mic cable, if horizontal and I'm holding it between overs, "improves" the RX signal. Hmm. This does not bode well for possible RFI which I think is causing issues related to yours.

All the best. Looking forward to your discoveries and solution.

Cheers, John
--
J. D. Erskine
VA7OTC CN88hk
Victoria, BC

Col,
You have done everything I would suggest except to use a dummy load instead of the antenna.? I have read a few issues where it appeared the antenna select acted opposite.? That is when the front antenna was selected, it was actually the rear that was connected.? I assume the 440 band works OK.? The UHF and VHF sections of this radio are a different path than the lower bands but the PA? is the same as I remember.? There is a calibration that may have drifted that is factory set for VSWR on the different bands.? I never had any issues with my 817 but my 818 gets stupid sometimes and gives the same indication as you have described.? I need to perform a factory reset to clear the condition.
--
Al Skierkiewicz
WB9UVJ