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eHam Forums / Antennas and Towers and more / RE: What is the OD of Buddipole mast?
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on: May 10, 2013, 08:32:26 PM
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I just measured it, it is only 1 and 1/8 inches OD at the base so it looks like you are out of luck. Cheers Michael VE3WMB P.S. What is the inside diameter of the surplus military mast. Could you put a 1 1/8 in pipe into the Buddipole mast and then slide your aluminum mast over the top ? I'm wondering if anyone knows (or could measure) the outside diameter of the Buddipole mast. I'm thinking about buying the tripod to use with some military surplus aluminum masts I bought which are 1.785". Not sure if they will fit in the Buddipole tripod or not.
73!
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eHam Forums / Antennas and Towers and more / RE: Length of ground mounted radials for 20 - 10m fan vertical?
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on: April 18, 2013, 07:48:23 AM
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Unless you plan to put down at least 20 radials, making the length of the radials greater that 1/8 wavelength at the lowest operating frequency really doesn't end up buying you much more. This statement is based on a study done a few years ago (I don't have a reference handy). Michael VE3WMB OK so heres the deal - im going back to an idea I had some time back for a fan vertical to provide the extra bands I need for the upcoming special event. An ex-Army Clansman 5.4m fibreglass mast will support the five antenna elements. 20m will be a wire running up the mast (this type of mast is actually designed to be used as a vertical in this way and has holes in the guy rings and tie offs for the purpose), whilst the 17m, 15m, 12m and 10m elements will be supported by horizontal fibreglass rods/tubes mounted in a cross formation at the top of the mast, spacing them a minimum of 1ft/30cm apart, using Dacron line from the element ends to the rods to keep them tight and straight (obviously each element will be a different length, so the line also acts as an insulator and extender), with dacron lines near the bottom to guy pegs to create the necessary bend in the elements so the majority of the element is parallel. Each element will then go to a common feedpoint box where the coax and the radials will connect. A flylead from this box goes to a radial plate, to which a minimum of four, and maximum of about sixteen radials can be connected (i say about, as I cant remember how many it can take!)
Now, the radials will all be laid on the ground, with pegs at the ends to keep them straight and secure. I am aware that in ground proximity they will not be resonant and its a case of the more the merrier. However, will the fact it is a multiband vertical have much influence ont he lengths needed for the radials?
It is my initial thought to make the radials a quarter wave on the lowest operating frequency, which in this case will be 20m, so about 5m.
Will I be fine with radials of this length when operating on the other bands? Also, ive heard that although more is better, up to about 32, that there is an issue with eight radials being of little benefit, even detrimental, over four? Or is this a myth?
How many I can use with it 'on the day' I dont yet know, it will depend on the size of the antenna field I have available to me (probably not huge) and the requirements for other antenna systems and other users.
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eHam Forums / Antennas and Towers and more / RE: above groung vertical with 1 radial
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on: April 08, 2013, 08:54:39 PM
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This antenna idea has been around for a while and it is sometimes referred to an "up and outer", especially if it is non-resonant and fed with parallel feeder. Normally when it is resonant it is called an "L" or L-dipole. It will give you some directivity in the direction that the horizontal leg is pointing and it does have both horizontal and vertical polarization so it can be very useful at times when the band is changing. The key thing is that the horizontal leg needs to be off of the ground, both for safety and to minimize ground losses but it does not have to be too far off of the ground. I have a 30m L up at the moment, fed with Twinlead and it works quite well on 40m through 20m with the horizontal leg about 7 feet off of the ground. This is reasonable alternative to a vertical dipole when you can't get enough height. Older versions of the ARRL antenna book suggest about 30 ft for both legs fed with ladder line for multiband coverage from 40m through 20n (I have a one from the late 1970s that includes this antenna, but it is omitted from later revisions). Like any antenna if you can get it up higher it will perform better and provide a lower takeoff angle for the horizontally polarized component. Cheers Michael VE3WMB P.S. And yes 2 elevated radials will give you an omni-directional pattern. With sloping radials it is sometimes called a "Wye" or inverted Y, for obvious reasons and if you can elevate it, it will most often outperform a ground-mounted vertical (unless you have a lot of ground radials down). From the Stepir site I have read that 2 above ground radials (180 degrees apart) are all that is needed to get a reasonable omni radiation pattern with decent efficiency. http://www.steppir.com/wp-content/uploads/2011/10/radial-systems-for-vertical-antennas.pdfIs this correct? If I have only 1 radial, this article says that I get a null of 12-15 dB in some direction. Is this true? Do I still get the same max gain in some direction? If so what directions? Perhaps one could select a single radial depending upon which direction they want to communicate. I know, lots of questions but good answers come from this forum. tks Dennis |
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eHam Forums / Antennas and Towers and more / RE: What's practical ext tuner for Yeasu ft 1000?
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on: March 21, 2013, 08:38:55 PM
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I have a double-sized G5RV (204 ft long) and I tune it with a LDG AT-100 PRO. I have no trouble matching the antenna on 160m through 10m. I have been using LDG autotuners since they produced their first tuners and they work well and they are quite reliable. Michael VE3WMB Last week I bought a like new Yaesu FT1000-D and it won't tune to 80/40 meters with the built-in tuner. What tuner should I buy? My antenna is a G5RV and it has worked great with my Kenwood TS450 and tunes on 80/40 meters with the Kenwood built-in tuner.
Would appreciate suggestions.
Don
WB4RG
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eHam Forums / Antennas and Towers and more / RE: Best 30 Meter Antenna
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on: March 21, 2013, 08:26:32 PM
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You might also look at a half square as an option. This would be equivalent to having phased verticals for 30m and will give you some gain and a bit of directivity over a single vertical. Try this article for starters : http://rudys.typepad.com/ant/files/antenna_halfsquare_array.pdfMichael VE3WMB Hi,
I have a largish lot, some RFI, and a need to operate 30 Meters... Been thinking of a full sized vertical, (with radial field), but the RFI issue slows me down there... Also been thinking of a loop... I have zero experience with loops... Has anyone used both, and if so how are they for DX?
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eHam Forums / Antennas and Towers and more / RE: Antennas for Cruise Ship Operation
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on: February 24, 2013, 01:39:28 PM
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if you were planning QRP operation I would suggest using an AlexLoop WalkHam Small Magnetic loop mounted on a camera tripod : http://www.alexloop.com/The WalkHam model packs up into a case the size of a small laptop bag, but it is only rated at 10w. Michael VE3WMB If you have experience operating from a cruise ship balcony please let me know what you used for an HF antenna.
I have an ICOM 706 rig and a power supply but I'm stumped as to what kind of an antenna to use. Length and weight are important considerations as I am confined to a wheelchair and hauling a long antenna on board the ship would be difficult.
I was thinking about maybe a ham stick mounted on the railing and grounded to the ship. Perhaps a manual screwdriver could be used?
What was your experience?
Rick
KB6GZ
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eHam Forums / Station Building / RE: High Balcony, dense RF urban environment QTH
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on: February 18, 2013, 09:46:54 PM
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D : I would suggest going with the KX3. The FT-897 / 857 have a more robust receiver than the the FT-817 but my experiences with these DC-to-Daylight rigs (I own an FT-817 and used to own an FT-897D) is that they are quite noisy in an RF Dense area. The combination of the AlexLoop and KX3 should allow you to make many QSOs and is portable enough that you can easily take it with you on trips or on an outing to a local park (lower noise levels). The latest KX3 firmware release (free) has introduced a DSP noise reduction feature and I have been told by a friend who has a KX3 that it works very well. The K2 is a great rig (I have one) but if I was given the choice between the K2 and a KX3 I would go for the KX3 as it has a better receiver and it is newer technology (the K2 was released back in 1998). Best of luck with your decision. I think that you will have a lot of fun with a KX3 and an AlexLoop. Michael VE3WMB / VA2NB Hi everyone,
So I will be moving into the 15th floor of a tall co-op in the next few weeks. The QTH is in Brooklyn, NY facing Manhattan to the North/West with exposure to the N, E and W. My station will have to be temporary, used on the balcony or inside the apartment near window. I will be operating below 20 watts so as not to interfere with anyone in the building. I have narrowed my antenna choice down to the Alex Loop. My concern is with the radio itself in such a high RF dense area. Would a Yaesu FT-817, 857, 897 or Icom 703 be absolutely rendered useless by RF or would they work fine with the loop? Or will I need a radio with better selectivity like an Elecraft K2 or KX3? I also don't want a large radio for operation.
Thanks,
D
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eHam Forums / CW / RE: I need a new keyer with 8 memories: suggestions?
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on: February 12, 2013, 06:42:04 PM
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I am assuming that you use a computer for logging ? If so I highly recommend the K1EL WKUSB keyer ( http://www.k1el.com/). The keyer itself has only 4 memory buttons if used in standalone mode but when it is connected to your computer via USB, it can be setup to send from your logging program using the Function keys on your keyboard which is very handy. Also while connected to the computer you can still use the paddles for input and vary the speed with the speed pot on the front of the keyer. The advantage of using the WKUSB vs keying your rig directly from the computer is the the WKUSB handles all of the CW timing and will always send perfect code. Many logging programs now support it. Michael VE3WMB
The memory buttons on my old keyer keep sticking. This is a problem--as I'm aging, I don't have the strength and coordination I used to have in my arms and hands, and the memory buttons are a big help, especially for contesting and DXing.
It's been many many years since I shopped for a keyer; I want at least 8 memory buttons (I have 4 now and it's not quite enough) and a speed control on the front panel for quick access. That's about all the requirements I can think of. :-)
I'd welcome hearing opinions on what keyer you use or would recommend. Thanks! --ken
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eHam Forums / Antenna Restrictions / RE: indoor antenna
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on: January 13, 2013, 08:33:38 PM
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Have you considered operating portable from a local park? You would probably do better with a temporary portable antenna than an indoor antenna at your office. I would recommend building something like a segmented dipole for the bands of interest and erecting it as an inverted vee, either using a line over a tree as a center support or a 30 ft fiberglass mast such as the DK9SK, MFJ or Jackkite. Here is a link to a typical segmented dipole design which can be modified to cover other bands. I build mine using spade lugs and alligator clips to connect the segments together. http://wa3wsj.homestead.com/iditarod_mini__dipole.pdfBest of luck Michael VE3WMB Help. My station is located in my business office. The office is located on the ground floor of a concrete block 2 story building that has no windows. My operating preferences are pretty much whatever my tech licenses priveledges are. Any help would be greatly appreciated, and I know I'll get it because I always get good advice from you guys out there.
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eHam Forums / Station Building / RE: Yaesu FT-817ND and BHI DSP (W4RT)
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on: January 12, 2013, 09:21:56 PM
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Audio filtering (DSP or otherwise) is no substitute for a reasonably narrow IF filter. If you want to operate CW on the FT-817 I suggest the 500 HZ IF filter. From what I have seen the BHI DSP doesn't work all that great on CW. If you are looking for DSP noise reduction for SSB and CW I recommend that you visit the West Mountain Radio site and look at the external CLRDSP or DSPspeaker (same DSP functionality for both). Both are external audio DSP solutions but seem to work well (I have a CLRDSP on my birthday wish-list) and because they are external they can be used on another rig, if you have one. Michael VE3WMB P.S. I suggest you listen to the sample files that West Mountain has on their website .. it features audio recordings along with the same audio (SSB and CW signals) pumped through the CLRDSP as well a couple of their competitors audio DSP solutions. I'm planning on getting an FT 817 with accessories.
Can the BHI DSP unit be used with headphones? Can it be used for CW or
is it for SSB only?
Is it worth getting the DSP AND the filters?
Thanks
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eHam Forums / QRP / RE: How to question - adding a keyer to the SW+
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on: January 12, 2013, 09:02:08 PM
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I put a K12 into my SW40+. I like the K1EL keyers because unless you care about having a lot of memories you can get by with just one SPST momentary switch. Also they run on 12V and I really like being able to set the speed by directly entering it into the keyer. I didn't bother tapping into the rigs audio chain so I just left the piezo speaker connected and disabled the keyer sidetone, that way I can use the rigs sidetone but I still hear the responses from the keyer when changing settings. Wiring is simple. Stereo jack connects to the paddle inputs on the keyer (dit generally goes to tip, dah to ring and ground to shield) and output of the keyer connects to the key input of the rig (i.e. the wires that originally went to the key jack) ... wire the the keyer power connections and you are ready to go. If you want to have a separate jack for straight key just wire it in parallel to the output of the keyer. I mounted the keyer upside down (ie solder side up) just above the main board at the back of the rig using a small L bracket attached to the rear panel of the enclosure so a screw hole in the back and a small switch on the front panel are the only physical changes to the rig enclosure. Michael VE3WMB There are external keyers like the AA0ZZ http://www.4sqrp.com/EzKeyer.php and chips which can be built into the enclosure. Has anyoen the documentation for adding an internal keyer? Or would you recommend an external one? K1EL's is out of stock. Norcal QRP Club sells one... 72 de Chris KF6VCI |
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eHam Forums / Station Building / RE: Advice for Purchasing Used Amateur Radios
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on: December 20, 2012, 05:46:25 PM
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Stephen : If you don't have any luck finding an elmer I suggest that you consider contacting the NE QRP Club. http://newenglandqrp.org/Much of the activity is around the Boston area and I know a lot of guys in the club who I am sure would be willing to give you a hand ... you might even develop an interest in low power (QRP) operation. Seriously the NE QRP Club has a great bunch of guys .. many I have met in person at LOBSTERCON. Cheers Michael VE3WMB
As for joining a club, I recently went to a local amateur radio club meeting and talk to a few of the members. I inquired about finding an "elmer" to give me some advice and a little knowledge exchange. I found that most of the member were friendly but they didn't seem interested in assisting me. They directed me to go and join the local net. I think I might have to try another club.
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eHam Forums / CW / RE: Compact indoor antenna?
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on: November 06, 2012, 07:00:11 PM
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Joe : You don't mention what bands you want to operate. I recently built a portable magnetic loop out of 10 feet of 3/8 inch copper tubing and I have had good success working DX on 10m through 15m in recent weeks using CW @ 5W. If you can find a decent quality butterfly or split stator capacitor the remaining parts can be purchased at Home Depot. My loop is very similar to K1RSTs at : http://www.kr1st.com/magloop.htmMichael VE3WMB P.S. Efficiency of a well constructed loop of this size can be close to 90% on 10m and dropping to about half that on 20m. Just moved to a new location. Don`t want to drill holes in walls of my new home for outdoor feed lines plus, I do not have attachment points for wire antennas. I am looking for plans for a compact indoor antenna that doesn`t have to be fastened to walls. I operate strictly low power cw. Shack will be on second floor of two storey wood frame house. Any ideas anyone? All replys appreciated.
Joe, VE9OCR
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eHam Forums / Antennas and Towers and more / RE: Doesn't vacuum variable flange resistance hurt magnetic loop performance?
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on: October 21, 2012, 07:46:32 AM
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The simple answer to your question is yes this mechanical connection can be a source of loss in a Mag Loop. However, unlike the wiper connection on an air variable capacitor, the mounting flange for a vacuum variable doesn't have to move. Just yesterday I was reading about a loop constructed by Frank N4SPP ( a very detailed web page BTW : http://www.nonstopsystems.com/radio/frank_radio_antenna_magloop.htm). I noticed that towards the bottom of the page that he used stainless steel hose clamps to make the connections to his vacuum variable, but his later measurements showed that this solution was introducing unacceptable losses. Often these sorts of losses are often not such a big issue on the higher bands (i.e. 10m) because the radiation resistance of the typical 3 foot Mag loop tends be higher there. Where it really kills performance is when you move down in frequency (i.e. 40m) because the typical 3 foot loop is very small for that band. What tends to happen as you move down in frequency to a lower band is that the mechanical losses become proportionally very large as compared to the radiation resistance of the loop. As the radiation resistance gets smaller this causes the efficiency to go down the toilet. I think that practically, if you can size the loop appropriately for the bands of interest, you can tolerate some mechanical losses and still have a very usable loop. BTW if you are not already a member, why not join us on the MagLoop Yahoo group. You will find a lot of like-mind Hams interested in both commercial and home-brew Mag Loops. Cheers Michael VE3WMB It looks like vacuum variable capacitors don't have solderable connections but are mounted with flanges. Doesn't that contact resistance hurt the performance of a magnetic loop? Isn't the contact resistance of the flanges pretty much the same thing as the wiper resistance with a typical air variable? Thanks for any thoughts you may have on this. I know nothing about air variables except what I see in the photos on eBay. (The reason I'm considering a vacuum variable is that the performance of my one-meter-square loop is astonishingly good! These things really work!)  |
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