DIGIWAVE ANT-7288 Super HDTV Digital 8-Bay Antenna UHF

[be236]

Anyone know about this antenna?

http://www.summitsource.com/digiwave...le-p-9544.html

Specifications:

DIGIWAVE ANT-7288
Digital UHF Outdoor HDTV Antenna
8 Active Element
Frequency Range: 470 - 862 MHz
Channels: 21 - 69
Antenna Gain: 20 - 36 dB
Beam Width H/V: H 60/ V32
Front-back Ratio: 22 dB
Output Impedance: 75 Ohm
Antenna Length: 820 mm

20-36dB antenna gain! Too good to be true?

[ADTech]

http://forum.tvfool.com/showthread.php?t=1559

[Dave Loudin]

Dude, you need to focus on the antennas we recommended or consult the antenna chart at digital home. Don't go chasing after clones of dubious quality and dubious claims.

[be236]

Originally Posted by Dave Loudin

Dude, you need to focus on the antennas we recommended or consult the antenna chart at digital home. Don't go chasing after clones of dubious quality and dubious claims.

Yeah, I know... It's just that I'm on the deepest fringe edge of reception here that I find the highest gain UHF as possible and been reading on the various sites and just stumbled on that one. Hence I'm just asking a lot of questions right now.. The claimed gain was just too good to pass up and ask.

Yes, I need to look at the antenna chart at digital home (if I can find its link again).

[oldjake135]

i have installed one , i think it works well , i live in Beaverton ont canada we are in the boon docks , i get all can stations pluse pbs bufflo and other american stations i also was told they are not any good.

[be236]

What channels can you get that show negative NM dB value?

[oldjake135]

ill check it out to morrow and let you no , all canadian cnal. are around 100, percent that i get.

[be236]

Yeah, I'm interested to know... I want to get some channels with NM -8dB to -15dB which are about 130km away...

Also, another question.. the gain listed seems way too high (too good)... so does this antenna come with its own power pre-amplifier? If so, that would make sense for them to claim this "high amp gain," and not "antenna gain."

[No static at all]

With such bloated gain figures, I would personally stay away from this product. They must have been smoking some pretty good stuff to come up with those huge numbers. Don't see any mention of amplification.

[MisterMe]

Originally Posted by oldjake135

i have installed one , i think it works well , i live in Beaverton ont canada we are in the boon docks , i get all can stations pluse pbs bufflo and other american stations i also was told they are not any good.

The DigiWave ANT-7288 is constructed using two 4-bay antennas mounted side-by-side with each side independently adjustable. To say that it does not work would have been a gross overstatement. I am sure that it is no worse than any other 4-bay antenna, but no better than any other 8-bay antenna. Those who are unfamiliar with TV antennas may be impressed with its performance. By way of comparison, a ChannelMaster CM-4221HD 4-bay has average UHF gain of 10.2 dB. Its larger sibling, the ChannelMaster CM-4228HD 8-bay has average gain of 12.0 dB. The DigiWave claims a gain over Channels 21-69 of 20-36 dB. I can see only two possibilities for such dramatic gain figures for the DigiWave. One is that the laws of physics are different for DigiWave. The other is that they are simply adding the dB levels of the two 4-bay sections. Suffice it to say, you can't do that [correctly].

Even though DigiWave's gain claims are false, it probably still does a decent job of pulling in UHF channels. It is the Ginsu knife phenomenon. For those old enough to remember the Ginsu knife infomercials, the Ginsu miracle knives could cut though tin cans and then cut tissue-thin tomato slices. The secret of the Ginsu knife is that it was stainless steel. Any decent stainless steel kitchen knife could do what the Ginsu knife did.

In a like manner, any decent 8-bay antenna will be as good or better than the DigiWave ANT-7288.

[oldjake135]

mine is a 8 bay antt. i get cblt sinal strengh 45, vall. 100, global sg. 56 val. 100 percent , tvo sig. 40 , val. 100, 23 buffalo sig .35, val., 100 , ckvr sig., 60 , val 100., chch sig 39., val 100 ctv sig., 60 val.,100 pbs only at night sig., 50,. val 80 percent most come off cn tower wich is about 70 miles away

[claudeM]

I agree that 36 db does not make sense. They must be quoting the front to back gain ratio.
Someone in marketing must have mixed up the engineering data in the translation.

[claudeM]

Back of the envelope antenna-gain calculation for an 8-Bay antenna compared to a single dipole:
Each time we double the number of dipoles we get 3 dB more gain.
Two dipoles = 3 dB more gain
Four dipoles = 3+3 dB more gain
Eight dipoles = 3+3+3dB more gain
Add an other 3dB when we add the reflector then the total 8-bay antenna with reflector = 12 dB better than a single dipole. (this is assuming all dipoles are adding in phase)

[Emu25]

I hav'nt tried the ANT-7288 but here's where you may be able to get it at a cheaper price,
http://www.homevisiontech.com/hdtv/o...v-antenna.html

[Pete Higgins]

Solid Signal had what appears to be this same antenna advertised this weekend as a “Solid Signal Xtreme Signal HDB8X High Definition Blade 8 Bay Xtreme Antenna (HDB8X)” for $59.99 with $0.05 shipping.

I don't believe their dB claims either, but for $60.04 delivered, I ordered one to try. Depending on how well engineered their matching harness is, I expect it to be in the ball park with any other 8-Bay.

I have a 40 year old Channel Master CM-4228 8-Bay Bow Tie up right now on a push-up mast and a 9 month old 91XG up on a 40' tower. Solid Signal expects to ship around the 1st of June (2013?) so when I get it I'll swap out the 4228 & (unscientifically) compare performance.

I can’t tell much difference between the 4228 & the 91XG with two notable exceptions; the 91XG reliably receives channel 43 (2.1 CBS) but has a hard time with channel 36 (4.1 NBC) and the 4228 reliably receives channel 36 (4.1 NBC) but has a hard time with channel 43 (2.1 CBS). The SNR for the rest of my UHF stations is usually within 1-2 dB with slightly over half favoring the 91XG.

[Pete Higgins]

As promised by Solid Signal, my $60.04 delivered HDB8X 8-Bay Bow Tie Antenna arrived this afternoon. It was double boxed in a heavy duty brown corrugated cardboard outer box and a thiner white corrugated cardboard inner box. The two 4-Bay panels were stored back-to-back in the white box with the cross beams loosely assembled and tie wrapped to them. There was also an assembly & installation manual and one rubber boot in a plastic bag.

The assembly & installation manual “What's Included” section lists:
(2) Mast Clamp Braces
(2) Regular Braces
(2) Sections of Antenna
(3) Weather Boots
(I only received one boot but that is all that is needed. Each length of 4-bay panel BALUN to combiner coax came (loosely) attached to their respective panel's BALUM and had a boot installed on each end.)

If you know how the antenna goes together assembly is straight forward, tool-less and easy. As with a lot of assembly manuals, however, the three listed steps (A, B & C) were not intuitively obvious. Fortunately, the manual listed a link to an assembly video: http://www.xtremesignal.com/hdb8x.html that can also be found on YouTube @ http://www.youtube.com/watch?feature...&v=BWfW1ncmOr4 (Thank you Mike!). I would strongly suggest that anybody assembling this antenna for the first time watch the video. FYI, to make mine look like the one in the manual & video I had to unscrew the combiner, rotate it 180 deg. and reattach it. Also, to have all the wing nuts on the back side of the antenna I had to reverse a number of the lower brace bolts. Fortunately, both sides of the metal mounting brackets (square tube clamps) have square cutouts to keep the plated carriage bolts from turning.

I am impressed with the way this antenna is designed. First off, the 16 individual 8” elements appear to be stamped from 1.66 mm (~0.065”) sheet aluminum. The matching harness inter-connecting the 16 elements appear to be formed from a relatively heavy 3.88 mm (~.153”) aluminum wire. Each element is held in place and in contact with the matching harness by a Phillips head screw into the plastic stand-off. This means that after a few years service when oxidation forms, unlike my Channel Master 4228 that has the wire elements riveted to plastic brackets, I should be able to remove the screws and clean all the contact areas. The element to harness contact area is a generous 11.12 mm (0.437”) wide. The BALUN is also bolted to the harness making all pressure contact areas accessible for cleaning. The 32 round through boom reflector tubes are 8.18 mm (0.322”) thick X ~19 ½ long. They are capped at the outer ends by a curved plastic extrusion that may mask progressively longer (~1”) rods at the center of each 2-Bay panel. The square supporting tubes measure 18.38 mm (0.723”). There is a lot of hardware provided to build this antenna that appears to result in a relatively robust design.

When fully assembled, the overall antenna is 32 1/2” tall X 47 7/8” wide X ~5 1/4” deep.

Hopefully, this weekend I'll have time to get it mounted and on the air.

[tripelo]

Originally Posted by Pete Higgins

...I am impressed with the way this antenna is designed. First off, the 16 individual 8” elements appear to be stamped from 1.66 mm (~0.065”) sheet aluminum...

Thanks Pete, for your assessment of the 8-bay construction.

The length of the elements seems encouraging. That 8 inch length is comparable to the 'original' CM-4228, so the antenna should have better low UHF response than say the DB-8 (6.5 inches as reported here). Also, the stamped flat element may have slightly better bandwidth (less SWR across the band) than the commonly used wire elements.

...Hopefully, this weekend I'll have time to get it mounted and on the air.

Yes, looking forward to your findings.

[Pete Higgins]

OK, I got the HDB8X together last night & couldn’t resist trying it.

By holding it up @ ~4’ AGL in my downstairs dining room, hooked to my computer’s Hauppauge HVR-1800 tuner I am able to watch two UHF channels from San Diego, channel 19 (69.1 KSWB) and channel 40 (39.1 NBC). These channels are both 88 miles @ ~166 deg. which means the signal is coming through the whole house. Pointed it towards LA (51 miles away) and got channel 36 (4.1 KNBC) with a SNR of 22.1, channel 31 (5.1 KTLA CW) with a SNR of 15.6 and the few others that I tried until my arm got tired. Maybe tonight’s just a fluke, but truthfully from down here, I didn’t expect to get anything other than channel 26 (24.1 KVCR) the PBS station 3.5 miles away.

[Pete Higgins]

I do not claim to “scientifically” test or even fairly compare multiple antennas. I can, however, report my real world results, recognizing the constraints I’m faced with. Make what you will of the information. I can confirm that lugging antennas and climbing ladders was a lot easier 50 years ago. It must be something in the water?

Since I can’t raise or lower my pushup mast by myself, I fixed mounted the new Solid Signal HDB8X on it below the rotor. The bottom of the HDB8X is @ 21’ 7” AGL, 5’ 9” below the bottom of the 40 year old Channel Master CM-4228 (not a new “HD” model). For the last several weeks, the CM-4228 has been connected through a new white 17’ RG-6 cable to the base of the pushup mast, an F-81 F-F barrel, 50’ of new white Magnavox M61210 RG-6 to a coax switch in the garage. My Winegard YA 1713 was similarly connected through a new black 17’ RG-6 cable, an F-81 F-F barrel to a 32 year old piece of RG-6 that also ran to the coax switch in the garage. During amplifier testing I verified there was no SNR variance @ UHF frequencies between using the new white vs using the old black garage coax runs.

I disconnected the black garage RG-6 cable from my YA 1713 and used that piece for testing the new HDB8X. The garage coax switch was used to switch between the CM-4228 & the HDB8X. The single output of the garage coax switch is connected to a new ~75’ thru-wall RG-6, run to my office computer and Hauppauge HVR-1800 tuner card used for this comparison. In other words, everything from the coax switch in the garage to the point of measurement was common for both antennas.

Using the rotor, I “bump” aligned the CM-4228 for maximum SNR on LA channel 36 (4.1 KNBC) and then, by eyeball, “fix” aligned the HDB8X to match. I purposely did not try to introduce the variance of two separate amplifiers although looking at my TV Fool report amplification is certainly called for: http://www.tvfool.com/?option=com_wr...1dda169109ca5c

The HVR-1800 was tuned to a channel & the SNR recorded, I then ran to the garage to throw the switch, returnd and record the new reading, tuned to the next channel, record it and repeated the process. Measurements were alternated between antennas so that each antennas value was recorded 20~30 seconds apart.

I also included measurements from my <1 year old Antennas Direct 91XG/Antennacraft Y10-7-13. These antennas are tower mounted @ ~40’ AGL and have individual +15 dB PCT MA2-M drop amplifiers connected via either an F-71 M-M barrel for the 91XG or a 300 ohm to 75 ohm BALUM and short piece of RG-6 for the Y10-7-13. The output of each amplifier connects to a UVSJ feeding ~125’ of new RG-6 that connects in my garage to a PCT MA2-4P +8dB/output per leg distribution amplifier one leg of which feeds a separate new run of RG-6 into my office. A different HVR-1800 tuner card & computer were used to take these readings. This is clearly an apple to oranges comparison, but is in-part justified by the fact that when I swapped the 91XG & CM-4228 last summer there wasn’t a significant difference in amplified performance. If nothing else it should be predictive of what I might achieve by adding a +23 dB amplification chain to the HDB8X and mounting it on the tower.



If it were still made, I would certainly recommend the Channel Master CM-4228 over the HDB8X if for no other reason than its High VHF capabilities. Within its design frequency range the unamplified HDB8X average UHF SNR of 13.975 compares favorably to the 13.7429 of the unamplified CM-4228. .23 difference is well within my margin of reading error since the tenths digit for both antennas was constantly changing. Had I been able to align the HDB8X with a rotor I may have been able to improve its SNR, especially for the San Diego stations. Last summer when I swapped out my brand new tower mounted 91XG with the CM-4228 I was really surprised when it matched the 91XG SNR’s within 1-2 dB on all channels. The 91XG was better on slightly over half of the channels but the CM-4228 definitely held its own. For that test I replaced the 91XG’s F-71 M-M barrel to PCT MA2-M connector with an ~18” piece of coax to the CM-4228’s 75/300 ohm BALUN keeping the amplifier, UVSJ and coax paths to the measurement computer fundamentally the same for both antennas. Extrapolating those results to today’s tests leads me to conclude that at my location there isn’t a significant UHF performance difference between the three antennas.

[Pete Higgins]

A compelling advertised feature of the HDB8X is its ability to align the 4-Bay panels to receive broadcasts originating from different directions. Since I predominately watch UHF stations coming from San Diego @ ~169 deg. (True) and Los Angeles @~292 deg. (292 – 169 = 123 deg.) I thought I would see how well it performed when configured with the panels orientated at a 123 deg. angle.

Similar to what I did yesterday, using the rotor, I “bump” aligned the CM-4228 for maximum SNR on San Diego channel 30 (15.1 KPBS) and then, by eyeball, “fix” aligned the non-movable HDB8X panel to match. I then “bump” aligned the CM-4228 for maximum SNR on LA channel 36 (4.1 KNBC) and then, by eyeball, “fix” aligned the movable HDB8X panel to match.
FYI, I had to tighten the wing nuts on the mast clamps until they were vertical to align the movable panel. To go more than ~130 deg. you’ll probably have to shorten the mast clamp bolts on the moveable panel side.

While I got my normal 3 San Diego UHF stations, I thought I had a bad panel pointing towards LA. Other than my local channel 26 (24.1 PBS TVFool @ -15.6) I couldn’t receive any LA stations. After several trips to the roof to check connections & alignment I decided to disconnect the LA panel from the combiner and use it like a standalone 4-Bay. I connected the combiner end of the HDB8X harness through an F-81 F-F barrel to the black coax used for testing yesterday. Configured standalone, I got channel 38 (30.1 ION) with an SNR in the 15.x range. Usually anything below 16.x isn’t watchable for very long. Clearly to be useable I was going to have to add an amplifier.

I connected the combiner end of the HDB8X harness through an F-81 F-F barrel to a 15’ section of RG-6 coax. I connected this new length of coax through a Channel Plus NF-471 55dB channel 24-29 notch filter to my Winegard AP-2870 amplifier’s UHF input. Configured this way I got 13 of the 19 channels I had yesterday. As expected, I lost the San Diego channels and all but one (PBS) of those in the NF-471 notch.

Pleased with the amplified single panel results, I reconnected the HDB8X harness to its combiner input and connected the 15’ section of RG-6 coax to the combiner output.



Combining the two antennas resulted in the total loss of 9 LA stations and dramatically reduced the others. Based on today’s testing results, for my location, the HDB8X is a competitive 8-Bay Bow Tie when used in its “flat panel” configuration but is nearly useless for leveraging its advertised multi-direction feature.



I suppose one advantage it still has over a conventional 8-Bay like my CM-4228 would be the ability to use it as 2 separate 4-Bays and run separate cables to a coaxial switch?

I also ran a series of tests substituting a PCT MA2-M +15 dB cable drop amp for the Winegard AP-2870. The Channel Plus NF-471 notch filter was not used with the MA2-M.