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Reviews Categories | Antennas: HF: Vertical, Wire, Loop | G2DYM Trap Dipole Help


Reviews Summary for G2DYM Trap Dipole
Reviews: 6 Average rating: 4.5/5 MSRP: $220 GBP (312 US Dollars)
Description: Anti-Interference, Anti-TVI, 2 KW power handling, trap dipole with 75 Ohm balanced line feeder plus optional 1:1 air-cored balun
Product is in production.
More info: http://
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G0YAP Rating: 2/5 May 10, 2012 10:38 Send this review to a friend
Over Priced, Needs time to get to work.  Time owned: 0 to 3 months
Wanted a multi band dipole for my home, made quite a few over the years. In a moment of madness, thought I,d look at this antenna. Liked the idea of low noise (always been a problem here). Contacted Spectrum Communications who now sell this antenna. Cost me £200 with balun!! Anyway..spoke to Tony at Spectrum, ordered it. Waited...waited..waited..chased..received phone call saying my credit card was not ok..turns out he took the number down wrong, promised it the next Wednesday, arrived following Saturday..(4 weeks from order)Anyhow, got it up..wouldn't tune up. I run a Yaesu FT450 with an auto atu. Contacted Spectrum, he blamed the rain, my tree, the ground, the russians.. mucked about with it for hours. After numerous e mails..got one asking me to check the wire lengths..all different. One was 18" over..Tony at Spectrums complained he was so busy and he must have made a mistake when building it, told me how difficult it was to measure wire!!. He offered to sent me a lug and shrink wrap to trim it(whoopee) Not great after spending £200.00!!! To cut a long story short, Spectrum customer service sucks. The antenna now works after I put an analyser on it and trimmed 4ft of each leg. The antenna does work very well but hind sight, I should have saved my money and just bought the traps and made it myself. Buy one if you want but be prepared for lousy customer service and allow time to muck about to get it to work.
 
M0AZE Rating: 5/5 Aug 8, 2010 01:14 Send this review to a friend
Check it out - it works  Time owned: 0 to 3 months
The antenna is a trap dipole and resonant on 80/40/20/10 and the original G2DYM antenna has seen some changes since Tony, G4CFY, took over the company in 2006. Traps and a newly developed feeder are the main enhancements. For more detail refer to the manufacturer website http://www.spectrumcomms.co.uk/G2DYM.htm

Before I offer my observations on this product the main stay antenna at my QTH have been G5RV’s with over 30 years reliable service. Issues feeding the G5 with coax, inherent noise ingress that raises the noise floor in the receiver by an inordinate amount at times was making 80 meters almost unusable. RF in the shack, despite deploying a choke in the feeder

A replacement for my G5RV has been somewhat of a sojourn for 2 years now and I have experimented with ‘doublets’, modifying the G5RV and all sorts of experiments. Some people say ‘ you get out of a mono band what you put in’ and good mono band antenna’s maybe the way, if only I had the space! Inverted ‘V’ meant more hardware for my neighbours and me. The ultimate being a tower and HF beam but I’ve decided that divorce is too expensive ☺

The G5RV has served me well for over 30 years. I suggest that if any modification is done; then change to balanced feeder if you can. Really makes a difference and the ‘old timers’ knew what they were on about.

The antenna:

Supplied unit is fully assembled complete with traps; wire and you need to specify the length of feeder (additional charge). The high quality balanced feeder is very slim, flexible and is ideal for my QTH where it is run underground in duct and requires a small hole to find its way into the shack. Benefit is that it has nowhere near the inherent issue ‘open wire’ has. A 1:1 balun for connection into a modern rig/tuner is required – which can be supplied at additional cost.

Respectful that every QTH is different and this is a multi-band antenna, I could only compare the new with the old with my ‘ears’ as no A/B switching tests were possible. No detrimental aesthetic effect of seeing the traps; the sag due to the additional weight is minimal. The slim line feeder is much better in the air than the 600 Ohm ladder line I used previously and the weight in the centre equally benefits, thus negating the need for a centre support mechanism. I continue to deploy the same counter balance weight.

To cope with the G5RV I deployed an LDG auto tuner (AT-200) as the Icom 756 PROIII would struggle on some bands. This antenna is well within the range of the tuner within the PROIII but the LDG remains, please remember this antenna is resonant on many of the main bands. A tree at one end of my property supports the dipole at approx 45 feet, sloping down to 30 feet at the chimney on the house. Very little stress on the supports is apparent which allowed me to ‘lower’ the profile of the support on the chimney (pleasing my tolerant neighbours).

On the air:

Main bands I use being 80, 20, 17 and 10. Conditions on 17 and 10 prevent any real comparison at this moment in time but remember this is non resonant on 17 the LDG will get it down to 1.3:1 but as it’s performance? 10 looks to be okay but alas lack of conditions prevents any real constructive comparison other than the noise is lower and not so sensitive to electrical impulse type interference. Of the few QSO’s on 10 they are ‘bigger’ by 1 to 2 ‘S’ points. My main comparison is on 80/40/20. On 80 I had to check the pre-amp was off as it is a louder signal and the terrible noise on 80 is 1 to 2 ‘S’ points down over the G5RV, signals generally at least 2 ‘S’ points up. It feels that the capture ratio has been increased and there is much more signal…

On 40 meters it equals the G5RV with an improvement on 20. Overall noise reduction across all bands is better which I do put down, in part, to the balanced feeder and the fact I am using a resonant antenna. I can see more power going out via the LDG AT-200 than the G5RV across all bands except 40.

Overall:

I cannot offer a computerised model together with frequency and SWR plots to verify my observations. But the advantages it gives me at my location both aesthetically and performance wise makes it a good choice. Overall I am very satisfied and it meets the criteria I had laid down during my search for a replacement antenna. I am not saying it’s perfect (what is?).

The company owner, Tony, is a regular columnist in a ham radio journal here in the UK called Practical Wireless and writes articles for those of us who are not in the ‘Radio Design’ profession. He has great experience and knowledge coupled with a great way of simplifying the most technical of topics. Relying on good design and well-engineered components he makes no false claims that his product is a miracle antenna. This is a trap dipole of W3DZZ origin and it works for me.

Best 73’s

Mike
 
G0EML Rating: 5/5 Oct 13, 2008 12:09 Send this review to a friend
great antenna, No TVI  Time owned: more than 12 months
Having used the G2DYM antenna now for over 7 years i can say that this antenna is realy great, and it still looks as good as the day i purchased it from Richard
Firstly i have the antenna in a Inverted V configeration and bent somewhat to fit into my garden, at about 25 feet in the centre
I have worked into the USA on 80 Meters and Canada on 40 meters a good number of times, it is 1 to 1 swr on 40 and 15 meters,But the swr is higher on other bands, but i over come this with the use of an ATU but have not had a great deal of use on the 20, 15, 10 bands as i have got a 3 el yagi for these bands

with my other antennas of the past i used coaxal cable, but i came over the telephone in my house, and other naughbours, also there sterio radio, but can say that after putting up the original G2DYM made by Richard i no longer have a problem, Richard is now retired but you can still buy a copy made by some company so if TVI is your problem go for this antenna 73 G0EML
 
G6CNQ Rating: 5/5 Jan 13, 2005 03:39 Send this review to a friend
Great results in a difficult QTH  Time owned: 0 to 3 months
Hi all
I am delighted with this aerial see below

Delivery time
The aerial arrive in double quick time on the Tuesday morning having only posted my cheque and order to Richard G2DYM on the previous Friday – Very fast service!

Build quality
I have been a short wave listener since 1949 and licensed amateur since 1981; in all of those years I have never purchased an aerial of such a high build quality. The aerial is strong and is clearly manufactured with care using the highest quality components. – Full marks!

Operation
Previously I have used - single band dipoles fed with coax, parallel dipoles coax fed, Carolina Windom 80 special, half size G5RV with 80 meter traps and latterly a full size G5RV – My location is close to an industrial estate and the QRM from that estate combined with QRM from our housing estate is intolerable.

You will have gathered from the above comments and the fact that I can only get about 60 ft of the aerial in a straight line with the ends dog legged! that I have a less than an ideal situation for erecting any form of aerial, especially being located in a housing estate! However with Richards kind and patient assistance on the telephone I have now modified the installation as Richard suggested and can report the following results.

a. The G2DYM with Richards feeder matching unit is far quieter than any other aerial I have ever installed at this QTH with the noise floor down by at least 4 ‘S’ points on the full size G5RV, thus enabling me to hear stations that would normally be buried in the noise.
b. It matches across the full bandwidth of all bands from 40 meters to 10 meters using my SGC MAC200 automatic ATU and on most bands using the built in ATU in my Kenwood TS2000 (I have not yet tried it on 160 meters) There appears to be no power loss as measured with my Bird meter, indicated output is 100 watts plus across all bands.
c. I have no TVI on any band, including 10 meters, and my RF sniffer detects zero RF in the shack and although the 75-ohm feeder runs alongside my telephone cables there is no interference caused to my telephones.
d. I am receiving signal reports several DB higher than with the full size G5RV
e. Dx contacts are far easier to make

The cost may seem a bit high but I can assure readers of this review that I consider it money well spent. We spend a lot of money on our equipment and to get the best results we should not begrudge spending a few pounds on getting the best aerial for our particular situation and therefore obtain the best results from our station.

So in summary I am absolutely delighted with all aspects of your excellent aerial and would not hesitate in recommending it to my friends

Regards Terry - G6CNQ
 
M1SOM Rating: 5/5 Mar 14, 2004 18:59 Send this review to a friend
worth the money  Time owned: 6 to 12 months
After using the g2dym trap dipole for the last 11
months I can confirm what an excellent aerial it
is .. I have it set at 20ft in a rectangle around
my small back garden and can work all round the
UK and Europe with ease and have also worked
Japan and New Zealand with just 100w from
my Kenwood TS50 .. I have made many contacts
on all the bands 80-10 using an MFJ989 atu ..
I am unable to run with a beam ... so feel I made
the right choice for a wire aerial .. details
108ft long fed with 75ohm twin feeder into a 1.1
balun .. then 1.5ft coax to the atu
 
GW3NCT Rating: 5/5 Jul 26, 2002 09:07 Send this review to a friend
First Class product and service  Time owned: 0 to 3 months
I was getting awful reports from my QTH. So bad I nearly packed it in. In fact I did go QRT for 3 years. Then I tried again and discovered an advert in the classifieds of Radcom. A phone call and he sent me full particulars. There is an option to upgrade to a heavy duty version, which I chose. G2DYM (Richard) is a retired ex-BBC transmitter and Antenna (he would say "aerial") engineer. The quality of build is outstanding. Well insulated flexiwire, consisting of 60 strands of .2 mm copper. The traps are sealed within a hard epoxy or similar compound. They look very rugged and are rated at 2 KW (untested because we are only allowed 400 Watts PEP in the UK). He will help you over the phone with suggestions for the best alignment for your QTH. Sending in a drawing helps here. Very helpful and free personal service. The centre suspended feedwire is well secured to be free of strain at the connections, likewise at the traps and the end insulators. These insulators are a black plastic or similar material. The ends of the wires are totally sealed where it wraps around the end insulators. The only exposed parts are the terminals on the baluns. I suppose these could be covered in PVC tape, but I haven't bothered. Time will tell how well it stands up to our very wet weather.

Performance seems outstanding. The optional balun is almost a requirement as most balanced outputs on ATU's have 4:1 internal baluns, expecting 300 Ohms or higher impedances. The balun is for internal use only and has simple wire terminals at one end and a 6 inch captive tail coax to the usual SO-239 plug.

I am very impressed with its performance, especially considering it is only suspended at the centre at around 34 feet and then slopes down in a 90 degree Vee almost to ground level. Its mounting mast is attached to the house and barely extends above the roof. There are tall trees of at least 50 feet height just 25 feet from the house on the same side as the antenna. I have no idea what the radiation pattern is like, but probably omni-directional judging from received reports.

Obviously any review of an antenna is very dependant on location and installation height. Here at my QTH, I have possibly one of the worst sites around for a wire antenna. However, it is working very well on 80 and 40 metres. I have to confess I have not yet worked 20, but only because condx are pretty poor at the moment. It is my only antenna - there is no way I would get planning approval for a beam mounted above this mast - pity.

My previous antenna was the G5RV. A commercial implementation that was the initial cause of my losing interest. However, I discovered this was caused (in my case anyway) by the 40 feet or so of buried coax. After taking the 450 Ohm feed directly onto the balanced terminals of the ATU it started working great. This suggestion came from G2DYM. However, after his so helpful suggestions I decided to buy his dipole anyway. For its build quality alone, it was worth it.

I cannot hand on my heart say it totally outperforms the 5RV. I was getting excellent reports on the 5RV after removing the coax, but I have confidence that the G2DYM is just as good and will last a lot longer.

73

Richard
GW3NCT
 


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