| N9PL |
Rating:     |
2002-06-09 | |
| Performs Better than Expected |
Time Owned: 0 to 3 months. |
I have had this antenna up for two weeks. I relocated to the Raleigh, NC area last summer. I had been on 5 acres of woods in central Wisconsin for the past 11 years and had a Pro-77A (10-40M) at 67 feet as well as a 160M OCF (80-160M) at 65 feet. I am now in an antenna restricted subdivision and needed an antenna that won't attract a lot of attention. My main interest has been DXing, so with no tower available, a vertical seemed to be the only option. Roof mounting was out because of CC&Rs, so a no radial vertical back in the trees seemed like the best choice. I was also looking hard at the R-8, but the extra 4 feet in height, top heavy design, many poor comments about it's predecessor, the R-7000, and $100 price difference swung the choice to the AV-640.
Some things you need to know if you are thinking about buying this antenna:
1) The counterpoise rods are 72" long, so the base requires a 12' clear circle. These long rods droop about 2'!
2) Hy-Gain recommends you mount the base 8' above ground but says it will work ok at 5'.
3) The capacity hats above each loading coil are not exactly like shown in the pictures. They are just straight spokes. The 40M spokes are 30" long. The top of the antenna requires a 5' open space to clear these spokes.
4) When you are holding a 25' long pole from the end to put it into the mast brackets (up 5-8') it doesn't take much wind to get it tipping over. It takes 2 people to put this antenna up!
My antenna assembled without incident. The directions were clear enough. Read the directions a couple of times and you will probably decide to do a few things in different order, like putting the counterpoise and matching network on after the antenna is on the mast, and pre-assembling some of the parts that have dozens of 6-32 screws and nuts.
I rated this antenna a 4 because of manufacturing quality problems. Some of the parts assembled at the factory were not square (capacity hat rings on the coil assembly), holes in the bottom tubing sections did not align well with the base insulator, the plastic insulators that hold the 1/4 wave resonators were very ragged, holes in the coil assembly tubing are larger than the heads of the 6-32 screws that go in them (I added SS washers). But with a little patience (and a ball peen hammer) everything went together.
The lower sections up through the coil assembly are double wall tubing. The hose clamps that hold the sections together are just strong enough to compress these double wall sections to tighten them.
My antenna is mounted on a 2" heavy wall aluminum mast (3' in the ground; 5' above). Mounted on this large mast, the much maligned base mounting plate seems to be holding the antenna straight.
My antenna is surrounded by pine trees of about the same height. The counterpoise rods go between a few of them. The top of the antenna has branches within a few feet (but clearing the 30" 40M capacity hat spokes). With everything assembled to nominal dimensions, I had 1:1 SWRs at the bottom of all bands except 30M. Using the information in the Assembly Manual, I moved the resonant point on several bands to give under 2:1 SWRs across all HF bands except 40M (under 2:1 from 7.000 to 7.160). This antenna is better than its BW and SWR specs as I have it installed.
Performance wise, this is not a 7 element beam on a 20 meter tower. EZNEC told me that it would be at least 2 to 3 S-units down from the antenna I had back in WI, so I wasn't expecting miracles. But I have been pleasantly surprised. In the 2 weeks that the antenna has been up, I have worked 80 countries (evenings and weekends...I work days), CW & SSB, mostly running 50 watts (I have been keeping the power down until I am certain I am not creating any local RFI). I have been able to work just about everything I can hear, but there have been a few times I couldn't crack a pile-up before the DX QRTed. These contacts have been on all HF bands from 40 to 10M. I haven't tried the antenna on 6M.
This antenna has an 80M resonance with a 1:1 SWR at 3.5 MHz. Not sure where this resonance is coming from, but it's there with 2 different feedline lengths. Hy-Gain doesn't advertise it. I haven't tried the antenna on 80, so don't know how well it will work there.
Bottom line is this antenna is performing better than I expected. Performance wise, I rate it a 5. Quality wise, a 3. Overall, a 4. |
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| W9CW |
Rating:      |
2002-05-06 | |
| Excellent Electrical Design |
Time Owned: more than 12 months. |
I replaced an old Cushcraft R4 with the AV-640. The AV-640 is mounted on the gable-end of the lower roof of my split-level home. Its mounting height is around 18 feet.
Rather than using the standard mounting arrangement with the plate and U-bolts and brackets supplied by Hy-Gain (MFJ), I mounted it as the R4 had been mounted. For the R4 installation, I made up a triangular-shaped mounting block from a piece of 2 x 8 stock to conform with the gable's facia and roof angle. This section of 2 x 8 was lag bolted into the structure of the house and created a very strong basis for an antenna mount. In the vertical centerline of this 2 x 8 piece, I routed an angled V-channel (depression) so that the 2" OD mounting section of the R4 would rest, and then lag bolted three (3) large clamps around the base section of the R4 and to the 2 x 8 piece at the gable-end of the house.
Since the base section (just below the insulated rod) on the AV-640 is only 1.5" OD, I purchased some 6061-T6 extruded aluminum tubing (2"OD with 0.25" wall = 1.5" ID). This was placed over and bolted to the stock 1.5" base section of the AV-640. And, this was then mounted to the 2 x 8 piece at the gable-end of the house as was the Cushcraft R4.
The point to this story is this . . . with this rigid mounting point and the routed V-channel in the 2 x 8 piece, the antenna stands perfectly vertical. I also placed a small length of the 2" OD extruded aluminum above the insulated section for the mounting of the matching network. Otherwise, I would have had to use a 0.25" spacer for mounting the top attachment for the matching network (difference between the 1.5" OD upper section and the 2.0" OD of the new base section). This short additional 2" OD section above the insulated rod adds a bit more structural rigidity to the lower section of the AV-640.
As to performance . . . it is an improvement over the R4 on the bands it covered (20, 15, 12, and 10). And, it works quite well on the other bands. VSWR meets or exceeds published specs, but more importantly, the antenna's efficiency is an improvement over the trapped Cushcraft R4. I have confirmed this with a "before and after" field intensity test.
The instruction manual is well written, but I noted a few areas where improvements could be made, i.e. change in the order of some assembly steps and a few typos. Otherwise, it was excellent.
Overall, I am very pleased with the AV-640. It seems very well constructed with high-quality components and all stainless steel hardware. The only weak link is the mounting plate system, but I eliminated that problem with the installtion configuration used at my QTH. |
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| K2WU |
Rating:      |
2002-05-01 | |
| works for me! |
Time Owned: more than 12 months. |
| I have to disagree with the previous post. I have the AV-640 ground mounted 15' from my house (totally blocked to the south) and 15' from a hill with a line of trees (totally blocked to the north). Is Mellish, Afghanistan, Ducie, Cocos, San Felix, South Sandwich, South Georgia, Baker good enough evidence? Worked all these, and a lot more, with ease with the AV-640. I've only compared it to a Butternut HF9, which I thought was a piece of junk. I highly recommend the AV-640. |
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| KC5TJG |
Rating:   |
2002-05-01 | |
| It ain't no R7... |
Time Owned: 0 to 3 months. |
I reviewed this antenna previously and noted the problem with the inadequate mounting system. I've now used the antenna enough to have formed an opinion on its operation. I'll compare it here, indirectly, to the Cushcraft R7.
I bought this AV640 to replace a Cushcraft R7. I also have several other antennas, both vertical (the Gap Voyager) and wire configurations. My old R7 often used to give a better signal on 10, 12, and 17 meters than my various wires (not always, but sometimes, depending on propagation) and was definitely superior to the Gap Voyager on 20 meters. On 40 meters, the Voyager was usually slightly superior to the R7.
I'm disappointed with the performance of the AV640. It gives a poorer signal on every band on which I can compare it to my other antennas. In other words, the AV640 is clearly inferior to the R7 in terms of performance. If you need a multi-band antenna with a small "footprint", this will get you on the air, but that's about all that can be said for it.
Why didn't I buy another Cushcraft? I was always pleasantly surprised with the performanced of the R7, but Cushcraft doesn't seem to be able to stick with one vertical. They frequently "upgrade" their multi-band vertical, and they don't keep replacement parts for their old models. And replacement parts were a must for the R7: the traps were constantly burning up. The antenna just couldn't take power.
I've been pretty happy with my Gap Voyager. I think my next multi-band vertical will be a Gap.
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|
| KH6AP |
Rating:      |
2002-03-23 | |
| Excellent |
Time Owned: 3 to 6 months. |
I was using an AV-620 for the past year and have worked over 200 countries with that antenna. The AV-620 even worked well on 30 meters with an antenna tuner. Big surprise!
I decided to put up the AV-640 due to the waning sun spot cycle. The antenna works equally as well as the AV-620 and it beats my expectations on 30 and 40 meter operation.
All of the comments that I wrote about the 620 apply to the 640.
Excellent Antenna
Aloha....KH6AP....Chip |
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| WA5US |
Rating:      |
2002-03-18 | |
| Great vertical antenna |
Time Owned: 0 to 3 months. |
| Easy to build and works as advertised. Even has a built-in coax choke and is DC-grounded for lightning protection. I have it mounted on a 16 foot pole at the side of the house. Be sure you mount this antenna on a sturdy mast. I had to add a 6 foot piece of galvanized pipe inside my TV mast to keep it from bending! The only negative is that the antenna will tilt slightly due to it's length and weight - doesn't affect the performance however. |
|
| K7JQ |
Rating:      |
2002-02-17 | |
| Very satisfied |
Time Owned: 6 to 12 months. |
| I have had this antenna for 6 months and am extremely happy with its performance. Well constructed and easy to assemble- well written manual. Holds up well under windy conditions here in the Phoenix , AZ area, but as in previous posting, the mounting plate and u-bolts could be a bit heftier- now leans slightly but no big deal. Very broad-banded with SWR under 1.6:1 across every band except 40 meters (to be expected). Minimum SWR on every band less than 1.3:1 at resonance. Mounted on 13 foot pole,well grounded, on side of house. This antenna replaced a Cushcraft R-7000 that had every malady described in the e-ham reviews. Got fed up and bought the AV-640. The antenna is very stable- no SWR fluctuations even in wet weather. No traps- just coils and capacity hats results in great mechanical and electrical strength and stability. Performs the way a vertical should. Highly recommended. |
|
| KR2I |
Rating:      |
2002-02-17 | |
| A Great Antenna |
Time Owned: 0 to 3 months. |
| This antenna is better than its compitition. I always thought that nothing would ever replace my R7 but boy was I wrong. My R7 finaly came down in a pretty bad wind storm that we had here in NJ not too long ago. Not being able to obtain spare parts for it I decided to go with the AV-640 and I am glad I did. All around I have been getting great signal reports with it useing only 40 watts of power. It took me one afternoon to assemble it and the instruction manual is very well written with good diagrams. After I got it up on my roof I quickly ran down to the shack to take some VSWR measurments and I could not believe my eyes. Nothing worse than a 1.3:1 VSWR on all band segments that I operate on 10 through 40. (I set the dementions for CW operation) The antenna is very well made with good quality parts and is very strong. I would recommend this antenna to anyone who has the need for a vertical. I rated the antenna a 5 because of its good quality construction and great performance. Five Stars goes to Hy-Gain for a great antenna. |
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| K5GBT |
Rating:  |
2001-11-14 | |
| The Hy-Gain warranty seems to be worthless! |
Time Owned: 3 to 6 months. |
| Easy to build and the instruction manual is good. I built it in one afternoon and set all tuning measurments in recommened areas. All bands are way out of the tune with totaly unacceptable SWR, typically more than 5:1. This is a well built antenna with sturdy tubing and good Stainless hardware. I put the antenna together last August and mounted it at the end of the house. Upon discovering that it was so baddly out of bands, I called the dealer from who I purchased it. I was told that I could disassemble it and ship it back. Or that I could just call Tom at Hy-Gain and get it fixed a lot quicker. I opted to call Tom. I was instructed to remeasure and recheck everything from ground radial length to the phase of the moon. After numerous calls to Tom, I was finally instructed to disassemble the matching box and try to find and repair the prroblem. Several more phone calls and Tom promising to, "get a new matching unit sent to you this week", the antenna is still an unusable whirlygig at the end of the house. Unfortunately, the Hy-Gain warranty seems to be something of a fairy tale. And I would advise extreme caution in purchasing one of thier products. |
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| KB7XO |
Rating:      |
2000-09-17 | |
| Hy-gain has done a great job |
Time Owned: 0 to 3 months. |
| Easy to build, instruction manual is good, but, there are some sequences in manual that could be done in preliminary set-up rather than get in the way later. Set all tuning in recommened areas, all are fine except 6M, and that can be reset quite easily from ladder or roof top. All other bands are very broad with acceptable SWR accross entire band, typically less than 2:1. This is a well built antenna, double tubing reinforced, good Stainless hardware, only about 20# but 25 ft long. Three of us put it up beside my garage with little effort. No traps, uses tuning stubs and top hats and best of all no ground radials. Put it up and left it up. It seems spendy but the quality is worth it. Not like some of the others I have seen. I recommend it wholeheartedly. |
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