I see the new DB4-E is for sale from the DHC sponsor- SnR, which provides performance figures. Similar to the 91XG, the gain seems to increase linearly from low to high channels, with a peak gain of 14.3 dbi at channel 51, the gain of the 91XG is about 15.5 at channel 51, and the F/B ratio is excellent.

Seems like the 91XG is still top dog, but if the DB4-E was stacked, could we expect an increase in gain of at least 2 dbi (beam width probably narrower, F/B increase maybe) then it might beat the 91XG...?

Using the RAW gain figures for DEB4e from our sponsors wesbite and the RAW gain for 91XG and DB4 from HDTV Primer

RAW Gain Comparison (DB4, DB4e, DB4eM, DB8e, DB8eM, 91XG)

DB4 = Stock
DB4e = Stock
DB4eM = Modified DB4e (swept forward whiskers & curved reflector)
DB8e = Stock DB4e x 2 vertical stack
DB8eM = DB4eM x 2 vertical stack
91XG = Stock

Channel / DB4 / DB4e / DB4eM / DB8e / DB8eM / 91XG

Channel 14 / 8.5 / 11.68 / 12.7 / 14.2 / 15.2 / 11.2

Channel 26 / 11.8 / 12.59 / 13.6 / 15.2 / 16.2 / 13.0

Channel 39 / 12.8 / 13.78 / 14.8 / 16.3 / 17.3 / 15.0

Channel 51 / 13.5 / 14.36 / 15.5 / 16.9 / 17.9 / 16.7


* Assuming ideal 2.5db gain from vertical stacking

* Assuming average 1db extra gain from 2" swept forward whiskers and placing matching curve on reflector screen. The actual gain will vary according to channel frequency???. The good news is that this mod can be done quickly by hand - without tools or additional parts and is easily reversible.

Assuming ideal stacking and mod performance:

DB4e vs 91XG:

UHF low end 14-26 - both are about equal
UHF mid end 27-39 - aprox 0.5db to 1.2db advantage to 91XG
UHF high end 40-51 - aprox 1.2db to 2.3db advantage to 91XG

DB4eM vs 91XG:

UHF low end 14-26 - aprox 0.5db to 1.5db advantage to DB4e
UHF mid end 27-39 - aprox equal to 0.5db advantage to DB4e
UHF high end 40-51 - aprox equal to 1db advantage to 91XG

DB8e vs 91XG:

UHF low end 14-26 - aprox 2-3db advantage to DB8e
UHF mid end 27-39 - aprox 1-2db advantage to DB8e
UHF high end 40-51 - aprox equal to 1db advantage to DB8e

DB8eM vs 91XG:

UHF low end 14-26 - aprox 3-4db advantage to DB8e
UHF mid end 27-39 - aprox 2-3db advantage to DB8e
UHF high end 40-51 - aprox 1-2db advantage to DB8e

Note: Stacking seems to be hit and miss as some people claim no improvement in signal strength for stack versus a single antenna. Your mileage may vary

* Assuming average 1db extra gain from 2" swept forward whiskers and placing matching curve on reflector screen.

MoreDB, What evidence do you have that this modification will have this effect on the DB4e? Don't forget this antenna has been re-designed so you can't extrapolate results from hacks to the DB4. My assumption is this hack won't work for the DB4e and will actually decrease the gain.

But maybe a simple stack would improve gain...

Solid Signal has the AD DB2e and DB4e up on their website now, with free shipping to the States. And they are a lot cheaper than on AD's site- $73 for the DB4e, and $56 for the DB2e.
If one of you folks from north of the border orders from them, how much duty do you have to pay?

i put one up yesterday,very happy with it . lots of gain with wide beam with here in Mississauga.citytv on the left and far right for Hamilton on the right side
no problem with this new db4e. i got it from our sponsor save and replay.

for DEB4e from our sponsors wesbite and theRAW gain for 91XG and DB4 from HDTV Primer

Our data sheet for the 91XG is now on our website. http://www.antennasdirect.com/store/91XG_HDTV_Antenna.html

Links to the DB2e and DB4e datasheets on our website were given in an earlier post.

swept forward whiskers and placing matching curve on reflector screen.

For commercial purposes, it has to be flat for packing and shipping. We'd certainly be interested in hearing of any "field improvements", especially if they can be well modeled.

But maybe a simple stack would improve gain...

Sure would, if executed properly. 2-3 dB additional gain would be anticipated. Horizontal beam-width would be roughly reduced in half.

guess i should have asked if anyone at AD has experimented making a pseudo DB8e out
of 2 - DB4e :P

Just got stock in this week, except for pre-production prototypes. Haven't had time yet to play around.

Solid Signal has the AD DB2e and DB4e up on their website now, with free shipping to the States. And they are a lot cheaper than on AD's site-

Solid Signal orders stuff by the truckload and gets a huge discount off list. It's their choice as to how much margin to add to their wholesale cost to come up with a selling price. If we get into pricing competition with business partners who buy in large quantity, they won't bother continuing to buy in quantity. Business decisions...


Edit: Engineer is experimenting with 610 mm center-to-center spacing for a horizontal stack...

And now for something completely different.

Our design engineer, Dr John Ross III , uses an insanely expensive software package (http://www.remcom.com/xf7) to model his designs that often make it into our finished products. One of his earlier data packages included some 3-D modelling of the C2 as it was developed. He did a series of 3-D plots, starting at 400 MHZ and stepping up to 800 MHz (in 50 MHZ increments) that allows visually shows how the forward lobe of the ClearStream 2 loop maintains its almost uniform shape and size across the entire design band.

While his original work was in JPEG format, our web guy pulled them into a PDF file and they're now posted on our website under "Documents" on the C2's product page. While the legend and the labeling needs to be added back in, it's still pretty cool to load up the PDF file, adjust the displayed size so one page fits one monitor screen, then page forward and back and see how the frontal lobe makes very little change while the rear lobes come and go.

Here's the direct link: http://www.antennasdirect.com/cmss_files/attachmentlibrary/ClearStream2_3D_Patterns.pdf

"MoreDB, What evidence do you have that this modification will have this effect on the DB4e?"

Wouldn't the same principal work for all bow ties? by sweeping the whiskers forward and with curved reflector you are narrowing the beam width to focus more gain in the forward direction? I stated aprox 1 DB gain increase as I remember people on this site with much more knowledgable than myself on such things, stating somewhere around the 1db gain figure.

I know that did that same mod on my stock DB4 and it DID make a difference on REAL world peformance on my very weak 1-2 edge channels from 113 miles away. I realize the DB4 and DB4e are two different antenna's (though both are bow tie designs) , I am tempted to purchase a DB4e to compare it stock plus modified versus the 91XG and M4.

Well, I had a few minutes and I just couldn't resist....

http://i1203.photobucket.com/albums/bb390/AntDirect/DB8e.jpg

My own subjective opinion, that is a darn nice looking antenna.

If one of you folks from north of the border orders from them, how much duty do you have to pay?"

I have ordered various items 3-4 times from their main competitor in the US and have never once been charged duty (even when I picked up at Canada Post), though it could have been luck.

Just curious: In California, we pay between 7.25 and 9.25 percent Sales Tax,
depending on which City you live in. And if an Internet purchase did NOT include
Sales Tax, we're SUPPOSED to pay the same amount as a "Use Tax" when filing
our State Tax Return...very loosely enforced...until you get tagged for an audit.

MOST on-line vendors I've used automatically charge the (variable) State Sales Tax,
so it isn't that much of a technical challenge to maintain a changing tax rate database.

California (et. al.) recently reached an "understanding" with Amazon.con to automatically
charge the State Sales Tax, beginning next Summer...unless Congress interveens
to deprive the various cash-starved states of their "rightful" Sales Tax revenue:
http://www.bloomberg.com/news/2011-09-23/amazon-s-california-sales-tax-reprieve-is-approved-by-brown.html

Aren't Canadian Residents immune to the (varying) U.S. State Sales Taxes?
Is this automatically done by vendors or do you have to provide an exemption form?
Or is the mechanism so difficult to obtain a Tax Exemption, it's not worth the hassl?
Like VAT Tax Exemption in European countries with a "special office" at the airport
you have to find with luggage (and kidz) all in tow...sorry, standard business hours.

So what is the Canadian Import Tax Rate???

Aren't Canadian Residents immune to the (varying) U.S. State Sales Taxes?

Yes, but Canadian residents should be charged the aplicable taxes (HST in BC) when picking up the parcel at Canada Post. Just like at the border though, when the Canada customs officer asks you what you are bringing back and you say $30-40 worth of XYZ, they often seerm to just let you through without paying anything. It is totally random and seems to be up to the discretion of the officer, similary Canada Post will randomly flag a postal shipment from the US and charge the full taxes.

This has been my experience and also what a Canada Post exployee told me.
The courier companies (especially UPS) seem to always always collect the taxes.

So what is the Canadian Import Tax Rate???

The current HST tax rate in BC Canada is 12% plus any appicable duties. The rate of duty will vary according to commodity and if it qualifies for NAFTA (a certificate of origin to show where the product was made is typically needed), the duty rate is zero. Duty rates are basically set to protect the businesses of the importing country. If the shipment is coming from outside North America and if no such product is made in the importing country, then the duty rate can be again 0%.

There is also something called "Most Favored Nation" where countries cannot discriminate between their trading partners on the list by charging excessive or lower duties.

Well, I had a few minutes and I just couldn't resist....

Nice! I think I just found my next experiment.

Awsome ADTech ! Will be interesting to see how that performs :)

Milehigh,

Welcome to the forum. More people will be able to give you better advice if you post in the Montreal thread here:

http://www.digitalhome.ca/forum/showthread.php?t=127724

Good luck!

edtrutone,

Have you compared this to a previous antenna? What gains have you seen?

Mine is going up this weekend in Brantford. New install.

the new one is much better it starts 12dbi to 14.25 all the way.
you will be happy with it,plus a bonus wb .no problem for ch 11 chch in
Mississauga.