Home station ground loop issue?

[scrotumola]

After reincarnating my super duper RF station, it is the best of all renditions. 25 years ago it was a Cobra 2000GTL and Ranger 2950 with footwarmer feeding a Super Scanner at 58' via 3 schedule 40 drilling pipe mast working 10/11 meters; a Kenwood 2m/440 at 35' on its own vent pipe mount and numerous pre trunk tracking era scanners. Later I added a Kenwood TS 430s on a horizontal dipole at 15'. One of the legs was actually secured to an eyelet on my utility pole! None of the antennas had any sort of bonding or lightning protection. All of them stayed up after I moved away and until my parents remodeled their home.

I recently purchased a new home and took some of the components of my old station out of storage and began construction of a new station/antenna farm. When I did this, I had one goal in mind: Do it right the first time, no matter what. No jerry-rigging or shade tree mechnics. (You get the gist) I had enjoyed 18+ years of unprotected sex with mother nature and she never once zapped me. Now I am paranoid as my investment is so much more substantial and I have much more to lose. Height above average terrain/treecover and general environment are similar to my parents except there are more 2 story homes in my neighborhood than my parents (both ours are single story)

Surge protector power strips were kept to a minimum. A multicoupler was added, every antenna feed into an entry bulkhead had to go through a lightning arrestor. All arrestors had feedlines to a common bonding post, that post was then routed to the ground rod, which was bonded with the mast's ground rod. All bonds consist of 1/2" copper braid.

You with me so far?

All Amateur gear (HF tranceivers, Amp, Tuners)with the exception of the 2m/400 (which is a mobile) have their chassis ground lugs bonded daisy chain to the interior bulkhead ground point. Even the Astron Power supply's ground lug is daisy chained to the ground lug.

When operating 150 watts HF, I don't really don't have any issues. However, when I turn the amp on, beginning at ~500 watts on up, I am getting RF into the station, even though my SWRs are relatively low. The RF was so bad, I had to disconnect my fire alarm sensors from my burglar alarm panel after RF chokes applied to their feedlines didn't work (ADT wasn't happy when I told them I pulled it)

Here is my setup, as revised:

TM731a(via astron power supply)->MFF Diplexer->interior bulkhead-><-exterior bulkhead<-lightning arrestor<-LMR-400 feedline<-Discone @ 42'

Pro2006->Stridsberg 4 Port->interior bulkhead-><-exterior bulkhead<-lightning arrestor<-feedline<-ST-2 antenna @ 38.5'
PSR-600-> " "
R2500-> " "
R2500-> " "

Ts940s->Heathkit Sb200->MFJ tuner->interiorbulkhead-><exterior bulkhead<-lightning arrestor<-LMR-400 feedline<-Dipole at 34.5' inverted v

All lightning arrestors have their ground lugs tied together at the exterior bulkhead rally point. From this point, a short run (less than 3') to the ground rod.

The below radio's chassis and power supply are daisy chained to the above, but not on the same mast as above.

TS430s (Via Kenwood Ps-430)->Vectron Tuner->interior bulkhead-><-exterior bulkhead<-lightning arrestor<-RG8<-separate horizontal dipole @ 14' in other remote part of yard


Is this a ground loop issue, or am I missing something?

Thanks.

Signed-One currently contributing to bald spot with no previous history of baldness.

 

[jack103]

All arrestors had feedlines to a common bonding post, that post was then routed to the ground rod, which was bonded with the mast's ground rod. All bonds consist of 1/2" copper braid.

Are the above ground rods tied into the main rod at the electrical service??

 

[jim202]

Not sure that I am clear what your using for the HF antenna. You made mention of a couple of
dipoles, but not if they were being used on the 500 watt HF amp.

I guess the first question is at what frequencies are you getting the HF problems at? I would
expect that your having the problem at some bands, but not all. You need to narrow this down
some for the rest of us mind readers trying to help.

By any chance have you looked at the output spectrum of your HF configuration? There always
is the slight chance you have some spurs and don't know it. A spectrum scope would let you
see just how clean your signal really is.

Do you get the RF problem when you have the mic gain low, or average, or cranked up and
are getting splatter several KHz away?

You didn't say what mode your operating, so I am guessing that it is SSB.

Jim

 

[scrotumola]

My apologies for not being more specific, I was attempting not to be too verbose in the original post.

To answer some questions... the two HF rigs are on totally separate feedlines to separate dipoles in isolated parts of the backyard, done to eliminate parasitic coupling.

Interference to the fire alarm was seen on 80m ~3.810, 3.830, 3.852 and I have reports of TVI (actually on neighbor's shielded computer speakers) on 20 meters.

I do not appear to have any issues operating 80 thru 20 on the 430, which is not used with the HF amp.

Intermittent instances of RF or a ground loop phenomenon in my signal have been evident on the 940-more pronounced when using the amp, but on rare occasion without it.

I have not been told I am splattering and at times have worked as net control in crowded conditions.

Mic gain has been watched closely, I am careful to avoid over-driving.

I've only been working SSB.

I do not have a spectrum analyzer/scope yet, but it is on the list (waiting for the right SM-220 with pan adapter to come around)

The antenna array and bulkhead grounds/rod are NOT bonded with the house's electrical main service ground. Their locations are diametrically opposed and would be approximately approx 140 feet of braid around the convoluted perimeter of the house, (sunroom, large patio) via most direct path. I have not ruled out doing this, but I am open to suggestion or alternative ideas. I had contemplated grounding to an outside water faucet, which would reduce the run by 80 feet, but haven't done so.


Thanks for replying.

~S~

 

[hydrolocked]

The antenna array and bulkhead grounds/rod are NOT bonded with the house's electrical main service ground. Their locations are diametrically opposed and would be approximately approx 140 feet of braid around the convoluted perimeter of the house, (sunroom, large patio) via most direct path. I have not ruled out doing this, but I am open to suggestion or alternative ideas. I had contemplated grounding to an outside water faucet, which would reduce the run by 80 feet, but haven't done so.

ALL GROUNDS MUST be tied TOGETHER, otherwise your protection is good for NOTHING.

If the house takes a hit, your radios are fried.

If an antenna takes a hit, you have the potential for the difference in ground potential to make some funny things happen.

the best grounding scheme you can put in place is a ground "ring" - 8' copper ground rods no more than 15' apart, all the way around the house, bonded together using a large non conductive cable - then tied to your equipment and antenna grounds, as well as the electrical service ground (reference MIL-HDBK-419A)

 

[KE5MC]

hydrolocked:
... using a large non conductive cable - then...

Might be a typo in there someplace.

scrotumola:
Only red flag I noticed was daisy-chained grounds. I recall reading installation recommendation that talked about each chassis grounded to a buss bar and the buss bar grounded to you outside stake.

 

[scrotumola]

I have since performed some additional internal reconfigurations. I have removed the Astron power supply from the station, relying on PS-430 to power the 2m/440, the lighted panel on the tuner, and the 940 amp-keying relay.

It had been suggested by another Ham that the Astron and its close proximity to the 940 may be causing issues. The load capacity of the PS-430 can handle my station's 12 volt requirements.

I still seem to be having issues with occasional RF and am taking steps to bonding the mast/station ground network with the service entrance's ground rod, but it probably won't happen until late next week.

Any other comments/suggestions?

 

[CCHLLM]

Well, as an experienced tower site and water/wastewater instrumentation and controls and telemetry engineer/technician, consultant, underground cable ditch-digger, ground system manual laborer, etc., for 40+ years, I been doing this grounding thing long enough to figure out that there's 1 truth: what lightning wants, lightning gets. However, there are some other truths that can help ward off Thor and his hammer. You seriously need to construct a ground buss and attach all components to that, not daisy chain 'em, and if everything is done right, you might even be rewarded with a significant improvement in performance of all the components.

Just for sh#ts and grins, go to the antenna jacks, leave the feedlines connected, use a multi-meter and take a reading on the resistance scale from the shield side of one HF feedline connector to the other HF feedline. Now do the same in the voltage mode, first on DC, then on AC. Now repeat between the feedline shield and the ground side of the power supply. If you find anything other than a miniscule few milliohms/millivolts, there's a potential for trouble when loaded with RF current. This is especially true if you find anything other than a miniscule AC voltage component between ground points, and to confirm what you're seeing, if your meter can display HZ, check to see if it's 60 HZ you're seeing. That's a real potential hazard for lightning and other hazards because there's no good connection between the house AC ground and your RF gear grounds.

This is where the SINGLE ground point for all the devices comes in. If installed properly, the single ground point should put any potential differentials to zero or near zero. That tends to greatly attenuate undesired radiation from rf-carrying surfaces and reduces the chances of damage in a lesser (dispersed) lightning strike. A full-on strike will get what it gets and then some no matter what you do.

With that being said, I must inject that doing the one point ground thing properly is a pain in the ass, sometimes a major pain in the ass, and if it can't be a true one point ground, then the next best thing is that all the separate ground points must be bonded together.

 

[prcguy]

It sounds like your alarm problem is probably due to high RF fields directly from the antenna, especially if your neighbors computer speakers are being affected. The alarm system equates to a giant antenna system if you consider all the wiring running all over the house in a typical installation. You would want to kill any RF on all the cables leading to the alarm panel including power and ground. Simple snap on RF chokes are not effective at HF, you need many turns through the core to get any affect and 10 turns is typical for type 43 or 61 ferrite mix. You should also place the chokes close to the alarm panel because the wire between the panel and choke is still an antenna. Placing a common mode choke at the antenna feed point (1:1 current balun) will also help keep RF off the coax and lower the possibility of RF getting into the radio area and onto ground lines common to the alarm system. Also check for poor or corroded alarm connections that can act as a diode and rectify RF, placing voltage in the audio range on the wiring in addition to RF.
prcguy

 

[hydrolocked]

hydrolocked:
... using a large non conductive cable - then...

Might be a typo in there someplace.

scrotumola:
Only red flag I noticed was daisy-chained grounds. I recall reading installation recommendation that talked about each chassis grounded to a buss bar and the buss bar grounded to you outside stake.

smartass.

yes - i meant to say large non INDuctive.

 

[scrotumola]

I'm just now reading this after a 36 hour marathon on the road. Lots to do and check out, but I will look into/perform each and every suggestion after sleep-plenty of it. Many many thanks for giving me a starting point to investigate. into. I was hoping to have this resolved for this weekend's Tx QSO party, but too many stars failed to align and I'll have to wait next year.

I hope to wake up in time to catch the Cowboys game later, BBQ and get ready for another week. The forecast doesnt seem to be threatening in the meantime, so I guess I'll continue my run of luck with mother nature until thursday.

Thanks again, and I will update.

~S~