Subject: Using a long wire john@neknetwork.com Date: Mon Mar 27 2000 - 22:07:35 EST Hello QRP'ers, I may have a chance to do some traveling on business during the year, and would love to spend some time operating my QRP rigs from a hotel. Right now I've got an SW80+ and FB40. I've got a RS shortwave that makes for a fairly decent receiver for the FB40 - I may build a DSW 40 real soon though, so perhaps I won't need the FB40. Anyway, I don't have a QRP antenna tuner per se, but my regular tuner is an MFJ949E that isn't too big and has a switch that shows QRP levels (sort of). I don't think using a dipole for 80 or 40 meters will be practical from a hotel room, so I'm wondering about dangling a longwire out a window and using the MFJ tuner. The docs for the tuner say that a good ground is essential when tuning a longwire, but I seriously doubt a good ground will be available on the 10'th floor of a hotel (or the first floor for that matter). So how essential is a good ground under these circumstances? What do others usually do? I really think operating on the road would be a gas. 72, John, KB1ENS -- John Wagner - john@neknetwork.com Web page: http://www.neknetwork.com Affordable web site hosting under your domain name! C/C++, Perl, CGI, RDBMS, Web site creation and Network Administration Subject: Re: Using a long wire BenNW7DX@aol.com Date: Mon Mar 27 2000 - 22:47:45 EST Hi John, Something that I do is just attach a half wavelength piece of wire to the ground. This will not substitute for earth ground, but will give you a good counterpoise to work off of. The counterpoise doesn't need to be straight either... you can run it all over the place and still have good results. Good luck, and I hope you decide to build a DSW-40... it is worth every penny!! 73, Ben - NW7DX Subject: Re: Using a long wire From: Steve Yates, AA5TB (aa5tb@swbell.net) Date: Mon Mar 27 2000 - 23:23:21 EST If you're going to use a single wire for the return current ("counterpoise"), a 1/4 wavelength wire is desired. A 1/2 wavelength wire will present a high impedance to the tuner and will be as effective as no wire. I would suggest an antenna that doesn't require a "counterpoise", such a continous loop, center fed dipole, or an end fed 1/2 wavelength wire. A hotel room is tough since many of the structures are constructed of steel. As mentioned, an antenna near or out the window will probably be required. 73, Steve Yates - AA5TB Fort Worth, TX - EM12gs http://home.swbell.net/aa5tb Subject: Re: Using a long wire From: Al Patrick (arp@inet4u.com) Date: Mon Mar 27 2000 - 23:08:48 EST john@neknetwork.com wrote: > good ground is essential when tuning a longwire, but I seriously doubt a > good ground will be available on the 10'th floor of a hotel (or the > first floor for that matter). > > So how essential is a good ground under these circumstances? What do > others usually do? I really think operating on the road would be a gas. > > John, KB1ENS John, Any 3-wire receptacle in the room should provide a groundING screw and / or terminal -- the center terminal somewhat U shaped is the groundING terminal as opposed to the larger of the two slotted terminals being the groundED conductor or current carrying conductor. The groundING conductor is for grounding the frames of equipment and should go to earth back at the main service equipment. Therefore, It should provide a very good EARTH ground - and should be available in EVERY motel or hotel room. Admitted, Some of the older units still may have the older 2-wire plugs but they should be few and far between and you probably wouldn't want to stay in those rooms anyway. It may pay to test them first to be sure. Al -- "The Truth is Hate, to Those Who Hate the Truth" Subject: Re: Using a long wire From: Pastor-kc1di (ELBC@PIVOT.NET) Date: Tue Mar 28 2000 - 06:14:36 EST Hi John, Cut a peice of wire 1/4 wave long for each band you plan to operate. This should be attached to the ground post of the Antenna tuner. it will work ok and put you on the air. some have said to use a 1/2wave wire.. but unless a 1/2 wave wire is attached to a very good earth ground it will show high impedence at the tuner and do little or no good at all.. 73 good luck Dave KC1DI PS one poster said to use the hotel power ground this is not a good saftey Idea, and water pipes may be all plastic with just a little metal going to fixtures so they are unreliable also.. Subject: Re: Using a long wire Wb8siw@aol.com Date: Tue Mar 28 2000 - 07:23:50 EST In a message dated 03/27/2000 10:14:06 PM Eastern Standard Time, john@neknetwork.com writes: << So how essential is a good ground under these circumstances? What do others usually do? I really think operating on the road would be a gas. >> Hi John: I travel quite a bit, and usually take a QRP rig along, so perhaps a few of my experiences will help. I usually take along a random wire for antenna. It's just No. 26 stranded on a chalk-line reel (disassemble the reel, replace the chalk line with the stranded No. 26, and reassemble). For a ground, I typically use either of two options: 1) I have a short length (about 15 feet) of tinned copper braid ground conductor with a large alligator clip on one end. 2) A second random wire of No. 26 stranded on a reel. The former allows me to take advantage of a suitable ground if one is available, such as a cold water pipe in the bathroom, steam heating device, and so forth. This is quite rare in the newer hotels, with todays plastic plumbing and so forth, but it can be advantageous in older facilities. The later option allows me to create a counterpoise using a random length of wire in the event that the building offers few grounding opportunities. I just connect the wire reel to the ground post and then run it out to a suitable length. I also use this later option during portable operation in the field. I'm not much for "messing" with ground rods and similar labor intensive devices during portable ops. Hope that helps. 73, Jim WB8SIW Subject: Re: Using a long wire Wb8siw@aol.com Date: Tue Mar 28 2000 - 07:34:07 EST In a message dated 03/27/2000 11:09:34 PM Eastern Standard Time, arp@inet4u.com writes: << John, Any 3-wire receptacle in the room should provide a groundING screw and / or terminal -- the center terminal somewhat U shaped is the groundING terminal as opposed to the larger of the two slotted terminals being the groundED conductor or current carrying conductor. The groundING conductor is for grounding the frames of equipment and should go to earth back at the main service equipment. Therefore, It should provide a very good EARTH ground - and should be available in EVERY motel or hotel room. Admitted, Some of the older units still may have the older 2-wire plugs but they should be few and far between and you probably wouldn't want to stay in those rooms anyway. It may pay to test them first to be sure. >> ------------------------------------------------------------------------------ -------------------------------- Hi Al: I just have to add a comment. This idea is probably OK under many circumstances, but potentially problematic, particularly for any higher power level. RF can develop significant voltages at points along a conductor. I would be uncomfortable under some circumstances because one can not be familiar with the condition of the AC ground, it's route, or what type of device(s) may be connected along it's length. Likewise, a fault in the safety ground combined with a defective device interconnected with it, while unlikely, could cause significant problems. An AC Mains ground is designed to work at 60 Hz, not High Frequencies, and therefore, it's a slightly different "animal." 73, Jim WB8SIW ----Switch to Safety----