Stupid Question from Someone Who Should Know the Answer But Doesn't.

[WX7P]

My computer keyboard ALWAYS locks up whenever I operate HF.

It doesn't matter if I use the tower or a laptop. Makes it kind of hard to use a logging program. Everytime I transmit, the keyboard locks up and I have to unplug the usb and replug it into the compter for the keyboard to work.

Everything is grounded, I think. I have a 6' ground rod with braid hooked up to all the radios and tuner. I even have the keyboard cord wrapped with a toroid.

I'm willing to rip everything out and start over. I had to keep a paper log for ARRL DX which really limited my time on the air. I want to get this straightened out before CQWW WPX at the end of the month, so I can make a semi-serious effort in that contest.

This is a free-fire zone. I'm prepared for the W9GB/KM1H style of vitriol for not being a real ham. :lol:

Give it to me straight, Doctor, I can take it!

14519

[KJ3N]

Type(s) of antenna, distance from operating position, and is it all bands, or just a few?

[WX7P]

Type(s) of antenna, distance from operating position, and is it all bands, or just a few?

Good questions.

The antenna is an ocf dipole that's fed with 100' rg-8 45 feet into a tree.
The tower is about 2 feet from the transceiver. When I use the laptop, it's right in front of the radio. I tried moving the laptop further away but I still had problems.

The lockups occur always on 15m and sometimes on 20m.

[KJ3N]

The antenna is an ocf dipole that's fed with 100' rg-8 45 feet into a tree.

OCFs are notorious for feedline radiation. In most designs, that's on purpose. Addition of a choke balun where the coax attaches to the OCF might help.


The tower is about 2 feet from the transceiver. When I use the laptop, it's right in front of the radio. I tried moving the laptop further away but I still had problems.

I'm referring to the distance from the antenna to the operating position. I'll have to assume a minimum of 45 feet. Not the worst I've seen.


The lockups occur always on 15m and sometimes on 20m.

Do you use an external keyboard with the laptop? On the tower, have you tried the usual toroid fixes (wrap keyboard cord on toroid)?

[NQ6U]

Are you using a mouse or other external USB device with the laptop? Those skinny cables that they use on mouses are notoriously poor when it comes to shielding.

[W3WN]

Does it happen with all keyboards or only one?
Have you tried wrapping some of the keyboard's cord around a torrid?
Have you tried a wireless keyboard?

[n0iu]

I know this doesn't help you at all whatsoever, but here is my "shack" --

http://i676.photobucket.com/albums/vv124/scottaschultz/shack_2_zps79403277.jpg
(Ignore the red arrow. I used this picture for something else. The arrow is pointing to my USB hub)

I can (and do) operate at 100 watts with no interference to my computer (which is right behind the monitor) or any of the peripheral devices. And as you can see, my router and cable modem are sitting right on top of the computer and my radio causes no issues with either of them.

Since I am not there to actually see your station, I can not give you a specific place to look but obviously you have a significant amount of stray RF in your shack.

In an ideal world, all of your grounds should come to one common point. Torroids might cure the symptoms, but they are not curing the disease. I don't have any torroids on any cables and for some crazy reason everything in the shack plays nice together.

[W2NAP]

had the same issue on a keyboard here, swapped it for a old school PS2 keyboard, problem went away.

for the most part, these made in china keyboard have 0 shielding on them. the one I had problems with, a cb'er going down the 4 lane highway 1/2 block from me would cause it to lock up, hell the little 4 watt DMR ht would cause it to lock.

[VE7DCW]

I know this doesn't help you at all whatsoever, but here is my "shack" --

http://i676.photobucket.com/albums/vv124/scottaschultz/shack_2_zps79403277.jpg
(Ignore the red arrow. I used this picture for something else. The arrow is pointing to my USB hub)

I can (and do) operate at 100 watts with no interference to my computer (which is right behind the monitor) or any of the peripheral devices. And as you can see, my router and cable modem are sitting right on top of the computer and my radio causes no issues with either of them.

Since I am not there to actually see your station, I can not give you a specific place to look but obviously you have a significant amount of stray RF in your shack.

In an ideal world, all of your grounds should come to one common point. Torroids might cure the symptoms, but they are not curing the disease. I don't have any torroids on any cables and for some crazy reason everything in the shack plays nice together.

A nice layout Scott.......a more efficient setup then the way mine looks at the moment! :yes:

[PA5COR]

Running the Fritzel FD-4 OCF with AMA 83 balun 1:6,7 and an 1:1 incorporated where the 1:1 should prevent RF on the outside of the coax.
Running anywhere from 10 to 1000 watts in it no problems detected in our or immediate closely lived society around me.

I DID however add ferrite clip on 43 material directly at the antenna coax.
Station is on the ground level and the ground net connected to all stuff including radial net and house Earth is just 7 feet away from the first ground rod.

My inverted L is 30 feet away and the bottom section looks directly into my livingroom/shack... no problems.
Using the former or new laptop nor my son's desktop computer have any probllem, just on 40 his monitor started to get scrambled with 1 KW, easiy solved with clip on ferrite on the cable.

Back to your problem, duno how you feed the OCF and if it has a 1:1 incorporated, but i think your coax might have RF feeding back.

[kb2vxa]

The ham I helped with a similar problem didn't have it with his computer, it was RF feedback into his Drake TR-7, but my solution may help here. It's a broadcast technique called single point grounding, that is all grounds are individual and brought to a single point where they are earthed. In his case it was a bit impractical, so the single point was in the basement below the shack and the tower ground not far away. All shack grounds were 1.5in braided copper ribbon and from the single point at the basement window to the tower was 4in solid copper strap. Eliminating the daisy chain and replacing it with single point solved the problem. That's one reason why it's used at broadcast transmitter plants, cell towers, repeater sites, etc., the other is to eliminate voltage differences that can be in the kilovolt range between equipment cabinets during a lightning strike when they're daisy chained. Just for fun use Ohm's Law to calculate voltage across one milohm with 50KA flowing through it. That if you haven't guessed can save equipment in the shack too.

[n6hcm]

do you connect your usb keyboard through an external hub? those are also often craptacular ...

[NQ6U]

I found that when I connected the case of my computer to the common shack ground, it made RFI issues worse, which was exactly the opposite of what one might expect.

[kb2vxa]

You just learned that only a small portion of RFI is radiated, most is conducted. Additionally, since I'll bet you didn't use a three prong adapter to disconnect the case ground in the power cord you formed a very large ground loop, a loop antenna. That's why on my last job all the test instruments had them to isolate them from each other and I keep them in my tool box, ground loops are insidious little buggers that throw sensitive instruments for a loop (sic or sick pun if you prefer).

I guess after reading this I don't have to tell you guys if you use a shack ground don't use the power cord protective ground or if you use the power cord protective ground don't use a shack ground. In simpler terms it's one ground, not two. This goes in another fashion for audio equipment as I found out during a course at The School Of Hard Knocks. Since my computer is the heart of my home entertainment system and the room layout is such that I had 10ft, more or less professional well shielded large diameter audio cables between the sound card and amplifier I was plagued by an impossible to get rid of low level hum. Connecting and disconnecting grounds, plugging and unplugging cables I finally came up with the right combination, the hum was gone. Just one little problem, I could only record or play only one channel. This would never do, but I had found the problem, I had broken a ground loop. Then my inner small voice whispered "Toslink", a little Google Fu later I discovered fiber optics and what the port with the glowing red light behind it on the back of my computer was for. A few adapters and two damn expensive glass fiber optic cables later there was no more hum. Here I should mention cheaper plastic fiber cables are fine for 1ft jumpers but my first try with 10ft ones went pear shaped, red glow but no signal.