DX-100B and RF Ground

[WO4K]

New to this group and the world of tube radios. I am putting together a second station. My receiver will be an HQ-129 that has been in the family for years. My xmtr will be a DX-100B I just acquired.

First let me say I have searched this forum and other on line sources, reading up on station grounding, including Bob McGraw's informative articles. Second, l think I have a pretty decent grounding system for my modern rig: each piece of equipment has a 1" tinned copper braid connecting to a 2"x10"Georgia Copper buss bar, then outside to four 8' bonded rods each about 16' apart, and the system bonded to the house electrical ground rod. The bus is located below the window, and my longest ground braid is about 6'. Each of the three antennas' coaxial lines are connected to Polyphasers.

The location of my new tube station in the shack will require two 12 foot long lengths of braid to connect transmitter and receiver to the common ground bus. My concern is for RF in the shack on 10 meters due to the length of the ground braid. In fact, the DX-100 manual cautions against 10' or longer lengths due to the possibility of introducing RF into the shack. I would like to hear some feedback and advice on this from you guys who have at this a while.

I am thinking I need to dump the GA Copper buss bar and run something like a  half-inch copper pipe behind my operating desk.  It would be about 10' long with a 90 degree bend qt 4'. But then I wonder if, especially because it will be round, it, too, will be subject to RF radiation.

Or am I over-thinking this whole thing?

Thoughts? Opinions? Advice?

Frank W4FLN

[KA2DZT]

You can reduce the inductance in the ground line by running multiple lengths of the ground buzz to the station main ground point.

Fred

[Pete, WA2CWA]

The DX-100 series is a fairly well shielded piece of equipment. Unless you plan on running open frame unshielded transmitters with unusual feedlines or unshielded tuners, your inside ground system sounds adequate. My ground buss consists of 1/2 inch copper braid that runs the length of my operating position (roughly 15 feet). 1/4 inch braid then connects between the 1/2 inch braid and each piece of equipment. All the feedlines are coax. For fun and giggles several years ago when I connected my Flex 5000 and SB-200 linear into the operating position, I used a 6 foot clip lead as my ground connection. It's still that way and no RF issues. I can't recall any RF issues with this overall arrangement in the many years of operating on HF or VHF/UHF frequencies.

Now, if you have something like this, you might have issues with RF:

[W2VW]

What are you using for an antenna and on what bands?

[N1BCG]

You might not be able to get a short run to your ground system, but do what you can to build an "immediate area" ground as Fred suggested. You can never have too much grounding. Bond every nearby metal objects together... water pipes, electrical conduit, air ducts, steel beams, etc. Their individual effectiveness will vary, but together, they'll help reduce RF hotspots by distributing the currents.

Do you have a copper water pipe coming into your house? That's a great ground point.

[WO4K]

What are you using for an antenna and on what bands?

Hex beam for 20, 15, 10 and dipoles for 80 and 40, all through an LDG AT-200ProII...although the use of the tuner is a bit of overkill since my SWR on each band is less than 1.6:1.

Frank, W4FLN

[WO4K]

Do you have a copper water pipe coming into your house? That's a great ground point.

Newer Florida house...no copper in the plumbing. 

[DMOD]

Do you have a copper water pipe coming into your house? That's a great ground point.

Newer Florida house...no copper in the plumbing. 

What about the water pipe at its source of entrance.

Up here, it hs to be at least 1" copper.

Phil

[WO4K]

Up here, it has to be at least 1" copper.

Steel pipe for the coldwater line up to, but not into, the house. After the house shutoff valve it is PVC into and throughout the house, for both hot and cold water. The water supply pipe is close to the electrical service into the house, about 40' from the shack. I have the coldwater supply pipe bonded to the station ground rods, as well as the house ground rod.

Frank W4FLN

[KA0HCP]

Why does your radio need an "RF" ground?  A: It doesn't.

There are at least five types of grounds, each with a purpose.  

Unfortunately the ARRL continues to perpetuate the idea that every station needs a ground rod outside the window and a wire to the radio, and then many other other items in the shack.

1.  Provide a modern 3 wire power cord to the radio.   This is your safety ground through house service ground.

2.  Build good antennas with good designs and ensure they have proper isolation with Baluns and chokes to eliminate Common Mode Current on the feedline.  If they are verticals or on towers, provide lightning grounds at the base.

3.  A ground rod with quality lightning arrestors for the feedlines outside the shack entrance is the next level of protection that is wise.  This should not be confused with an RF ground, and there is no need to connect radio and equipment to it.  This rod should be Bonded to the house main service ground.

If you do this you will probably never be electrocuted, nor have RF in the shack and never need any additional grounding in the shack.

Most RF problems are due to poorly designed/built/installed antennas.

[KA2DZT]

Anytime you put additional ground rods into the ground those ground rods, as a group, should be bonded to the electrical service entrance ground.  This is done to reduce voltage gradients between two different locations in the earth.

The OP stated he has done this.  His question was directed to the longer length ground buzz to his main station ground from his new operating position.  Like I stated,  he can reduce the length inductance by using multiple runs of ground cable between the two operating position.  It's like putting two coils in parallel, the inductance divides like two resistors in parallel.

Fred

[W2VW]

Looks like the antennas are the easy to tame variety and you may have no R.F. in the shack to get rid of.

If you said OCF or an ex CB sleeve vertical things might get interesting.

As you probably know, a DX-100 into a 1.6:1 VSWR load will not benefit from an antenna tuner.

All it does is normalize the instrumentation to 50 ohms.

Save the tuner for the newer finals. It probably has some loss near 50 ohm radiation resistances anyway.

Look for you on the air 

[Steve - K4HX]

The ground system you have now is likely good enough. Don't bother doing anything else until you actually experience a problem.

[w1vtp]

The ground system you have now is likely good enough. Don't bother doing anything else until you actually experience a problem.

Agree - but I went ahead and did this anyway. 

GROUND NORTH WALL 1 connects to an 8" wide heavy age copper flashing that goes outside under the sill to my ground system. The shack was literally built around my ground system as well as the tower system.

GROUND NORTH WALL 2 is a continuation to the west wall.

GROUND WEST WALL continues around the corner to complete the ground system.  I connect my equipment using hose clamps and heavy gage braid

Steve says it (and others)- don't look for problems. My I say, just solve them if they occur.  I had the luxury of designing my ham shack

[kb2vxa]

"The ground system you have now is likely good enough. Don't bother doing anything else until you actually experience a problem."

Jezakly, I had a very similar ground set up at my original QTH and never had any problems. Well maybe one, lightning missed everything else and hit an 18ft antenna mounted on a 10ft pipe driven into the ground with 1ft above for the antenna mount. It went through the direct burial type coass underground for 50ft into the shack arcing from the end to the ground bus blowing the PL-259 off the end in the process. NEVER put it past lightning, no matter how well you think your station is protected something's gonna get zorched!

[KB2WIG]

Like a 12 ga loaded with No.4s,  a good ground is nice to have in your house.

Here at wig radio, we have underground feed for the lectricity. The main antenna is run underground for about 70 feet before it comes into the house. The entrance is a Cu sheet with a Polyphaser protection devise. I've driven a 8' ground rod here, and bonded it back with #2 to the lectrical  entrance, where I drove an extra rod. The 10m close line dipole enters the home at a different place. I'm going to have to bond this back to the other entrance(s). I'm lazy.

klc

[WO4K]

Thank you, gentlemen, for the great responses. Alan, I am in awe of your grounding system. Steve, I think you said it well. I will ground the DX 100B to the copper ground buss and see if I get any problems. Thanks, guys.

Frank, W4FLN

[K9DXL]

Just to add another 2 cents worth:  I have a DX-100 (non-B).  If its previous owner has not already done so, you will want to re-cap the power supplies.  This is a good time to add a three wire cord and plug.  This is a good basic first step.  Many fine ways of getting the job done in the above comments.  Have fun with your DX-100B!

[John K5PRO]

W1VTP's grounding system is beautiful.

I have a single bar in my shack, behind the main desk, and all radios have a braid to it. Through the wall this bar is attached to a heavy multistranded conductor to my house electric meter ground. Its not really a good RF ground, but a safety ground for lightning events and for equipment faults - independent of coax shields and AC cord grounds.

Vintage broadcast operations (MW and HF typical) often would have a wide strap from the transmitter to outdoors, and sometimes to studio equipment as well. I don't think this practice is as often regarded as it used to be.

Here are some examples of heavy industrial grounds, for a high power RF system. The large copper pipes beside the copper strap in underfloor trench are amplifier cooling lines, with deionized water. The other two are in the same building.