Digitenna DUV-DF First Impressions

[lithOTA]

I've been curious about these Digitennas for some time now, but there was no way I was going to spend $200-plus for one. When a new-in-box DUV-DF (the second-largest model) showed up on Ebay for $35, I jumped at the chance.
The packaging is pretty impressive- there is an outer carton, and inside is a cardboard "drawer" that holds the antenna parts. The "drawer" has slots and folds that hold the pieces securely, unlike other brands that just throw the antenna into a box and call it good.
The construction seems about average, but some of the materials are a little weak. The directors, reflector elements, and long VHF element are all made from the same wimpy channeled aluminium. It's very light weight, but I can see how they could be broken by snow, ice, or bird loads. There are a lot of sharp edges that can (and did) draw blood, so wear gloves if you're squeamish.
While this is not a particularly long antenna, there are two items that stand out as being much larger than other Yagis. The funky-looking driven element dipole (called the "DUV Module") is a full 22 inches wide (!) and the corner reflector, while not unusually wide, is very tall- four elements per side, and a total height of about 3 feet.
There is a second mast clamp on the lower reflector boom, but it is just an off-the-shelf hardware store u-clamp that is not actually attached to the boom. Seems like a tacked-on afterthought to me.
I only had time to set it up in my attic, and it works very well, but there was some mild tropo enhancement last night. I will wait until I have more nominal conditions before making any performance judgements.
One thing that I'd like to try are some swap comparisons with my 91XG. Since the 91XG's stellar performance comes from the wicked directors and the huge corner reflector, and the Digitenna's claimed advantage is because of the funky dipole and balun module, I want to try putting the DUV module on the 91XG's boom, and vice-versa. It will be interesting to see how the cross-bred rigs perform compared to each other, and to the stock configurations.

[holl_ands]

It could be modeled if you provided dimensions and photos, esp details for the Bowtie....

[Jase88]

I've never heard of them before. The design looks reminiscent of Antennacraft.

It's obviously optimized for UHF. The gain on VHF is pretty anemic: Only 2.5dBd on channel 7, and 3.2dBd on channel 13. Peak UHF gain appears to be on channel 39, with 12.8dBd.

There is another model, the DUV-XF (extreme fringe) that has somewhat better gain.

[lithOTA]

Originally Posted by holl_ands

It could be modeled if you provided dimensions and photos, esp details for the Bowtie....

I'll try to get some dims and photos posted. I would be interested to see what the models say.

[insider22]

An engineer (broadcasting specialist) at my workplace was saying very good things about this company.

I am curious about your review.

[lithOTA]

Last night, I crawled up into the attic and repositioned the DUV-DF slightly. I had originally mounted it where I had another UHF Yagi (the front portion of an old CM 3016), but in this location there was a 2X4 truss running diagonally right in front of the dipole. So I moved it about 2 feet over, to a spot with a little more breathing room. This helped with the UHF stations that I'm trying to get, but I still want to reserve judgements until after this weekend. It should be tropo-free, and I'll be parked in front of the tube all weekend watching the Wild Card round of the playoffs.
The new location did allow me to install the DUV-DF's long VHF element that attaches to the back end of the boom. I can report that there definitely is some high-VHF gain, as it is grabbing an RF13 that is about 30 degrees left of center. So far, it is not quite as good as my homebuilt K6STI Yagi, but there is usable gain- last night, it was 17:1 SNR with 100% signal level. The K6STI usually runs 19 or 20:1 in the same location.

[re_nelson]

...the Digitenna's claimed advantage is because of the funky dipole and balun module,

Could you please describe the balun module in more detail? Is it like the 91XG design in that the elements "go into" the balun or does it appear attached to the Digitenna's dipole? Or something else?

[Trip]

I have the DUV-XF and the DUV Vii.

I am very impressed with the Vii's VHF performance for its size and it has replaced the generic rabbit ears I used to carry around for that purpose. I'm currently using it in conjunction with a metal garbage can as my local reception solution down here in Chattanooga, Tennessee.

https://fbcdn-sphotos-a.akamaihd.net...40439332_n.jpg

https://fbcdn-sphotos-a.akamaihd.net...24945758_n.jpg

The DUV-XF is what I'm using for reception of Atlanta, 100 miles away. I have nothing to compare it to, but it seems to be doing okay. Its VHF performance leaves something to be desired, but on UHF it seems to be pretty decent. I'm having a lot of co-channel interference problems which make a straight performance evaluation difficult. I'm having to carefully balance the desired Atlanta digital signals with undesired nearby analogs to get something usable out of it. I now have it mounted on a pole and will be uploading photos in the near future, but for now... https://fbcdn-sphotos-a.akamaihd.net...61119630_n.jpg

http://www.rabbitears.info/dxlocation.php?id=265

EDIT: New photos, taken last weekend.

https://fbcdn-sphotos-a.akamaihd.net...49735536_n.jpg

https://fbcdn-sphotos-a.akamaihd.net...28530776_n.jpg

- Trip

[lithOTA]

I got tired of trying to fool around with this thing in my attic- it's just too cramped, and like the 91Xg, I can set it up but can't adjust it's position or azimuth. So since it was warm on Saturday, I put it outside on the mast at 23 ft AGL, through the Kitztech KT-200 coax preamp.

On all of my 70-mile Milwaukee and 85-mile Madison UHFs, the DUV-DF beats the HBU-33 and Clearstream 4 by about 2 points of SNR. This is about 3-4 points better than the Winegard 9022 and 4400, and within about 2 points of the mighty 91XG. In fact, the DUV-DF does something that so far, only the 91XG can do- recieve WMSN-47 RF49 during the daytime. It's not quite in the 91XG's league, but it's close.
On the VHFs, it had no response whatsoever to my RF8 in Milwaukee, but that's not a suprise- my Winegard 1713 just barely gets it. On my RF13 at 44 miles (NM +13.7), it was running SNR 20:1/signal 100%, and it didn't sufffer being off-target by 30 degrees. There was occasional impulse noise, and a few times it would drop down to 14 or 15:1, which tanked the picture. I would guess that you need your VHF-high to have an NM of at least 20 for the Digitenna to get it good enough for reliable use.
The cheezy afterthought second clamp for the lower reflector boom works well. It holds the lower boom firmly against the mast, which is a good thing because the DUV-DF's boom sections are only attached to each other by way of the DUV module, which is plastic.
I will get it down and get some nice photos, and I'll take a crack at measurements. I'm not sure how best to measure and draw that crazy origami driven element- the only way to get it accurately might be to pound it flat!

[insider22]

Digitenna seem the only company to produce antenna that were design for the new UHf band. Other antennas still use th 14-69 Channel plan.

[300ohm]

I'm not sure how best to measure and draw that crazy origami driven element- the only way to get it accurately might be to pound it flat!

I dont think you have to do anything that drastic, heh.
Just take close ups of it and measure one half of the driven element since its symmetrical to the other half. Measure the center to each tip point and center to each fold point, and then do the same for the height. Then measure the total length of the driven element as mounted, and the air space in between.

[EdT]

Good review, would be interested to also know how directional these are compare to regular yaghi and bowtie designs !

Here is a news clip for them:


Get to see what is in that little black box ...LoL

[300ohm]

and balun module, I want to try putting the DUV module on the 91XG's boom, and vice-versa. It will be interesting to see how the cross-bred rigs perform compared to each other, and to the stock configurations.

I dont think thats going to work out well at all. The impedance of single bowtie with a 1" gap is typically around 600 ohms. Folding the bowtie up isnt going to change that a lot. It requires a custom 8:1 balun.
The quasi folded dipole on the 91Xg is closer to 300 ohms, needing a common 4:1 balun. So using the 8:1 balun on the 91xg will give it a much higher mismatch loss and vice versa.

The use of the term "booster circuit" for a balun is quite misleading, but not unprecedented as Gavin antennas did the same in the 1960's.
Without the use of a balun on the single bowtie, the mismatch losses would be quite high, so the balun does "boost" the Net Gain over a no balun scenario. But its not boosting anything that wasnt there before, its just decreasing losses.

[holl_ands]

I analyzed 6-Whisker, 4-Whisker, Enclosed and Indented (wire model) Bowties here:
http://imageevent.com/holl_ands/dipoles/uhfbowties
Although 800-ohm impedance had better match over a narrow range of low freqs,
the best overall match was about 300-ohm for all four shapes, presuming
1.5-in Feedpoint separation. [And 1.0-in won't be much different.]

As usual, I included 4nec2 models if you want to vary Feedpoint Gap
and search for the "best" characteristic impedance....

Perhaps you meant SOLID sheet metal bowties????
I haven't run that one....and doubt that it has 800-ohm impedance.
Care to provide supporting info????

[300ohm]

Care to provide supporting info????

Youll have to wait a few days to a week for that, Im still optimizing the 8ft X 8ft KISS antenna for the lower uhf channels and dont want to mess that up, heh.

IIRC, I got the 600 ohm figure from the ARRL antenna book in their discussion of the 2 crossed and 1 parallel design of the 4 bays resulting in 300 ohms. When I was modeling my RS classic bowtie, I got about the same figure if I recall, and it does vary with frequency. Only when the feed point was narrowed to 1.5 mm, as it is in real life, did it match closely to 300 ohms overall.