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Latest Posts

Topic Author Posted On
RF Grounds, when a ground and when a Antenna? 1200bruce 2 days, 22 hours ago
Any wire that carries RF current that is not balanced (with equal and opposite currents) or shielded is going to be part of your antenna system. It will radiate to some extent, causing interference in your shack and changing the antenna's radiation pattern. Shortening the ground connections helps, but the way to eliminate RF currents where they shouldn't be is to make sure your antenna is properly balanced -- so that no currents flow on the outside of your coax, and minimal currents flow in the ground system. (You might also use a current mode 1:1 "unun" in your coax run to stop currents outside the shield.) From the RF point of view, when the antenna is just right, there is no ground current -- and you don't need an RF ground at all. You still do need a good ground for AC and lightning protection.

73 Martin AA6E
Cell Phone Site and Repeater Site K7IHI 4 days, 11 hours ago
One opinion FWIW: Technically possible, although some cell services are in the high UHF range, so I can't be 100% sure. Getting physical access to the tower or a support building might be very difficult however -- at a price you could afford. Risk for the tower operator, insurance issues, etc.

73 Martin AA6E
Accessing ARRL Handbook CD ROM on IPAD niemoell 1 week, 2 days ago
Any PDF reader app on iTunes should do the job, not only Acrobat. However, your problem may be how to transfer a CDROM to the iPad. For this, you will probably need to use a PC (or even better, a Macintosh) that can mount the disk and share it over the network. You may need to consult an iPad / iOS expert about the details of the transfer of the PDF files - using WiFi most likely. Alternatively, there might be an option to mount a USB-interfaced CDROM drive directly on the iPad. Again, you may need an iPad expert to help. (Not me, sorry!)

73 Martin AA6E
New Tranceiver, Old Electric K7RMA 1 week, 2 days ago
The AC load of your radio gear will peak at 200 Watts, give or take, averaging less than probably 50W. Your AC circuits are probably fused for at least 10 Amps, way more than you will need. So you should be fine for your radio, as far as the basic wiring size goes.

The main worry I would have in your situation is AC safety. This is an issue for radio work, but also for lots of modern appliances that have 3-wire plugs. Running with 2-wire adapters and a dangling ground wire is dangerous. (A proper ground ensures that any AC fault in your gear is shorted to ground, blowing your fuse or breaker and saving your bacon!) I would seriously look at rewiring the house to modern standards.

Yes, you can provide your own ground for the radio, but be sure it's a good ground for AC (not over a couple of ohms resistance). Secondarily, it probably wants to serve as an RF ground and a lightning ground. Doing a good job for all 3 types of ground means low resistance (at 60 Hz), low inductance (at RF), and short runs (less than ~ 0.1 wavelength at RF is best). It can be difficult to satisfy all those conditions, but do the best you can.

For more, check the ARRL Web on Grounding.

73 Martin AA6E
Any truth to this rumor? W0SJF 3 weeks ago
Many of us have a ham badge that gives our callsign and name. It's useful at club meetings, conventions, or other activities.

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