Yaesu 891, MFJ-939Y and grounding questions

[CB590]

So got my new rig all setup here in the house and tied the radio to the tuner with nice 12awg wire on the rear per norm. Then attached via wire to ground rod outside (via wire with wire nut). Cuts the RX noise and all good.

End fed on a slope about 16 feet on one end and about 12 feet on other and 17 foot of counterpoise and 25 feet of coax feedline.

I just noticed with the ground wire (wire nut to undo) the auto tuner won't tune some stations. I undo the ground wire (with wire but under shelf) and it tunes. Keep in mind the tuner and radio are still grounded together on the back of the rigs and I just disconnect the wire nut.

With ground wire on.



Ground wire disconnected at the "nut". Radio and tuner still bonded with ground wire.

 

[CB590]

Sample of noise level. With ground off (4-5) then on (1-2). About 3-4db difference.

 

[CB590]

Here's the endfed (9:1). It's about 50 feet of 12THHN and from 14' up on house end and slopes to like 12' on other end to post in yard. Both ends have standoffs. Counterpoise is the green wire (12THHN) and is 17' long.

Maybe the counterpoise since it passes by shack feed point when coupled with ground wire at antenna mast point is causing RF loop??

 

[Shadetree Mechanic]

The tuner likes the floating ground and uses it as a counterpoise. The counterpoise goes away when grounded? or Sounds like grounding it causes a ground loop?

 

[CB590]

The tuner likes the floating ground and uses it as a counterpoise. The counterpoise goes away when grounded? or Sounds like grounding it causes a ground loop?

That's what I'm thinking.

I do notice a previously tuned freq without ground wire does not like the ground wire reattached for TXing. It goes right into Tune mode on the auto tuner and kicks me out so to speak of the previous tune and gives me the 3 beep thing.

I also notice the TUNE SWR is better without the ground wire vs with ground wire. Like 1.5 with ground and 1.2 (guess) without ground

 

[Shadetree Mechanic]

Might try some ferrite beads on the coax between radio and tuner if you have any handy. Ferrite after the tuner might be good too. This will make your ground wire the only path for RF.

 

[CB590]

Might try some ferrite beads on the coax between radio and tuner if you have any handy. Ferrite after the tuner might be good too. This will make your ground wire the only path for RF.

only 6" of coax. I think it's RG316 or RG400 (as shown in this pic from yesterday's case post). Maybe I will try RG8x jumper I got here.

 

[CB590]

Swapped the RG400 (looked up the code on the coax) for RG8x jumper. No change.