I can I tell if there is garbage on the input when there is garbage all around? My Chip Angle should kill much of the noise right off the bat. Splitting the antennas and duplexer should cover the cavities, right?

This is an older thread but timely for me.

I am moving my 2 meter machine from my home at 6,400 feet in the mountains to Heap's Peak. Heap's Peak is DIRTY. I am told that the only way to get a decent system is split antennas and a duplexer. 3 cavities on RX and 3 cavities on TX. Because of 74kW FM transmitter next to my tower the TX antenna would be up top and the RX antenna would be below. I don't know the spacing that is required but both antennas are DB224e's.

Respectfully, could you tell me what is so difficult in this? I must be missing something. As far as a balanced system turn the TX power down?

Heap's is gonna be a sonna-mo-beach but besides covering all of So. Calif. on the metropolitan side it covers all of the desert as well. Advice on this particular site are welcomed. I plan on using a WaCom WP-642 BpBr. I currently have the repeater on a Sinclair Res-Lok but the cable harness doesn't use a T at the end. Besides, I think the 8" cavities will be better suited on such a noisy site. I am one mile away listening to another repeater and my 5 watt HT can barely be heard. I don't want that! I'll stay here and give up 1/2 of the desert if I have to.

Can you tell me what I need to do to make split antennas and a duplexer work? I also have a two cavity Chip Angle with a 17dB preamp. Does it go in front of the duplexer or behind? It's 1MHz window would put a cleaner signal into the duplexers.

@Steve, I haven't heard you on HF in awhile.

Bob - AF6D
147.705 ( - ) 167.9

Did you use the basic model or the premium? I looked at the basic model and wasn't impresed with its quality.

It's pretty loose. About 1/4" or less. But loose. That's why I was looking at galvanzied. If I have to I'll put these in stock and get some crossover plates that use u-bolts. I'd rather not.

It might be but it looks close -- like right at 1.5". I measured the diameter of the tower leg and divided by Pi and thought I was right on the money. See what happens when I think?

I bought some heavy duty galvamized steel crossover clamps that were supposed to go down to 1 1/2" and actually they won't. They are loosy, goosy. I thought of taking the next larger size glavanized pipe to a band saw and splitting it into two halves to make shims.  But I'm not a pipe guy.

What size galvanzied pipe will a 1 1/2" O.D. pipe slide into? Without threads...

I've heard of a bacon stretcher but not a wire stretcher. Do they sell them at HRO? 

Well, I think I've decided on THREE 50 gallon drums filled with sand. That will be about 1300 lbs. of vertical weight and a horizontal footprint or base. The winds do kick up pretty good up here. I will have a steel plate welded connecting the three drums together top and bottom. A 3" hole at the top for a mast and a 3" flange mount at the bottom to attach the mast. Up 15 feet or so to a 3" to 2" reducer and then up anther 30 feet onto which the 28 foot vertical will be afixed. I'll have to have the top of the 2" mast lathed down to 1 7/8" to accomdate the mounting of the ZeroFive. I will then have to figure out how to guy it at the mid point since it won't be on the roof of the house.

Another option would be a 20 foot triangular tower section with a bottom plate onto which steel drums could be welded. I like this approach, too. This would allow me to push it up against the 12" beams of my upper balcony and afix it with minimal disturbance to the structure. There are already bolt holes and a cap could be made to go over the 12" x 4" beam and line up with the bolt holes at the 10 foot mark. I could still do the same with the 3" mast and saddle clamps.

This is the odd part. It has worked since 2008 when I moved down here to Running Springs. I dropped the antenna yesterday and inspoected the coils -- fine as expected because 75/80m operation is fine. But the antenna is low across the board. It is just more noticable at 20m and above. The only change is the large tree next to it has grown quite large. There has always been a 2m and 6m vertical on my upper balcony. We don't have rain cutters up here in snow country and there is minimal wiring in the attic. I chnaged the coax to a new shorter run of LMR-400 just "because" and it of course had no effect. You still heard me on 20m 100 miles away

Thank you. I appreciate your replies. I am familiar with the purpose of a tuner but was really asking about reeiver performance as a result of resonance. This isn't VHF where an inch would make a difference. I suppose the question is how much loss in power I have through the tuner. I'll try an experiment after my nap with a dummy load and measure PO. I'll maure the output at the amp into a dummy load and then I'll attach another SWR meter and measure PO to the antenna and compare notes. I've notcied that the meters in a LDG often read differently than stand-alone meters.

This antenna has worked great for several years. I miss my SteppIR but a guy has to do what he can do when leasing. The SWR was never an issue but I have a Live Oak tree that has grown within feet of the feed point. This antenna has always been close the roof of the house (20 feet or so at the feed point, but most of the wire isn't.) Conclusion: a bushy tree! I can either wait for fall or get the tree saw out. Other antennas now nearby are probably a factor as well. I spend most of my time on 80/40 where the SWR without the tuner is 1.6:1 so this isn't a big deal. It really is only because now I know the antenna performs poorly on 20 and above.

It appears that my commercially made multi-band fan dipole antenna is low in frequency across the board. The SWR at 14.200 for example is 5:1. It is relatively good at 1.6:1 on 80 and 40 where I work anyway. It was recommend that I cut the elements to get closer to resonance. I have an excellent LDG AT-1000 autotuner that handles the SWR and I wonder:

Does cutting the dipoles closer to resonance actually have an affect on receive, am I being nicer to my tuner by being resonant, both? or it just doesn't matter so much?

I am not a contester but I think the practice is just wrong. But hey... on contest days I don't turn the rig on. I don't turn it on much these days anyway. I am very disappointed with the receive on the Yaesu FT-2000, but that is another post probably never to be started. One day my daughter's cancer will be gone for good, I'll own a home again and put the SteppIR back up with a DX-5000 or something current and better.

One question I don't recall seeing answered was that if one was running one exciter into two amplifiers each feeding a yagi one over the other but not phased as far as cable goes, am I correct that the ERP would increase but that the pattern wouldn't change nor would the gain?

This has become a fascinating topic to me!

It seems to me that if one were running two phased antennas they are either narrowing the H field or the E field. Unless the amplifier was inserted into the 75 ohm feeder for each antenna they wouldn't really be in phase as we think of with stacking, right? One would just have two antennas with separate amplifiers pointed in the same direction. I can easily see remoting U/VHF amps on the tower making stacking possible like this but not from the shack. But then again I'm a complete stacking rookie Otherwise I guess one would have very long 75 ohm cable runs.

I find it fascinating and revealing that contesters would actually use this technique

My Opal GT has the 5 foot tall Egg Beater center mounted in the roof! I looked like something out of the freakin' Jetsons! LOL. With a Cobra 148GTL with all the modifications and a 400 watt amp I worked the world. That's when I got bitten as a ham. I loved my Opal GT and it was a chic magnet no less! When not mobile I'd sit on my base station modified for extended range and I'd stay up until the sun would come up as I worked the grey line on 10 meters that I didn't know about yet.

My first radio was a National Radio with 18 tubes. Knowing nothing about loading coils or traps I fashioned a loaded folded dipole and strung it between the trees. I used red/white striped bell wire and wound "coils" over wooden dowels. It worked damn good and I'd DX AM broadcast stations with it. By using the main tuner and the sub-tuner I could actually get up to 50MHz and regularly used it to listen to Los Angeles County Sheriff back when they were on 39MHz. I used slope detection in the AM mode.

My love of antenna design was born back then as well. Seeing what I had done my neighbor, a SK now, gave me a block of wood and 5 metal rods from which I made my first quarter wave ground plane by drilling into the block of would at 45's and epoxy gluing them in place. I connected the radials and direct soldered the coax. It worked okay but I found that I could take a CD radio antenna and shorten the 5/8 wave vertical element and get killer low band reception. Back then, in the 70's, low band was still really popular.

This past brings me here wondering about phased Yagi's pointed either in one direction or bi-directional. Does one amp running through a power divider have more or less punch than phased antennas each with their own amp.

The Zero Five is a 28 foot tall groundplane antenna with 6 100" radials attached. It wants to be a least 6 feet off the ground. http://www.zerofive-antennas.com/content/groundplane-10-40-meter-high-performance-multiband-vertical-antenna Otherwise your suggestion makes perfect sense. When ground mounted it is slightly less effective than my Alpha Delta DXCC wire dipole at 60-80 feet. My friend has a ZeroFive atop an 8,000 foot mountain at a repeater site and he kicks my butt. I have a FT-2000 with current PEP firmware and a 1KW amp. He has a a Kendwood TS-430 and 100 watts and works the world. I'm at 6,300 feet also at a repeater site and cannot compete. It really tixkws me off to have better equipment and hear less (although the FT-2000 is questionable.) The solution according to ZeroFive is to get the antenna as high as possible.

Thanks for the input. I'd love more feedback on the roof mount I have designed.