I took down the old XG91 today, and replaced it with a new unit that was sent by AD.

The balun box was allowing water inside via the rivet holding the top right active element connection to the box. Water was then pooling on the clear backside of the PCB layer, and dripping around to the underside, where it was causing electrical interference.

http://img822.imageshack.us/img822/2089/img3005b.jpg (http://img822.imageshack.us/i/img3005b.jpg/)

This is the underside of the PCB, showing signs of corrosion near where the active elements are joined (corrosion is near the tip of the screwdriver).

The installation of the new unit went reasonably well. However, one side of an alumimum director fluttered off after installation. These aluminum directors are a joke. They're snapped into either side of a plastic clip, which is then clipped into the boom. The quality is somewhat poor. The net result is that I was left without one director at the very front of the antenna. Though performance doesn't appear to be impacted negatively as far as I can tell.

I could have grabbed a director from the old antenna. The logistics of doing so would have been difficult, however, given that my "helper" wandered off elsewhere. ;)

thanks for posting the pics Jase.
I seen your tower pic too. You brave soul.

No problem!
The message here is that you should always seal up your stuff well before mounting it.

I just Finished Evaluating C1,C2,C4 .They are amazing ,small and power full
UHF Antenna, good CH9 on C4 high VHF channel as well.:p

I like my CS2. Mounted in an attic in the north end of Toronto, I have no problem pulling in virtually all Toronto and Buffalo stations (this is with a CM7778 hooked up). I've no doubt it would do it without the amp if it wasn't in an attic, and it sure is a compact antenna. I can also get 11.1 out of Hamilton with it pointed at Buffalo, which is a bonus.

UHF Corner Reflector Yagi: Antennas Direct 91XG Hardware Hacks (http://www.digitalhome.ca/forum/showthread.php?t=111398)
UHF Bowtie Reflector: Antennas Direct DB8 Hardware Hacks (http://www.digitalhome.ca/forum/showthread.php?t=124306)
VHF-HI Antenna: Antennas Direct's C5 VHF-HI Antenna - Models? (http://www.digitalhome.ca/forum/showthread.php?t=107428)
UHF/VHF-HI Bowtie Reflector: Redesigned DB-2 & DB-4 for UHF & VHF-HI (http://www.digitalhome.ca/forum/showthread.php?t=131236)

thanks for the info and pics Jase

I took my XG91 down and sealed all over this past weekend

as others have said, I'd also like to say the performance of the XG91 is a fantastic - a vast improvement over my old setup (stacked CM4221s)

I get all Buffalo & Toronto stations consistently and still get ION most evenings (thought it might go away after Summer)

Hi all,

Depite loving my SBGH (thanks 300, OTAcanuk and everyone else for your help and tips), am going to pick up a commercial antenna this week.
Judging by experience and TVfool, I could get all my channels w/ a CM4221 or an AD DB4; however, would a bigger antenna be beneficial (AD db8 or Cm4228)?

My thinking is at the Canadian conversion deadline, and when smaller US stations go digital, I will be all set (ie- there are still about half a dozen smaller US stations that havent converted yet). Or is just getting somethibng bigger just overkill?

I'm purchasing a new antenna this week locally. 2 different stores offer the bellow:

Option #1 CM4228HD (119$), CM7777 PreAMP (99$) and mount kit (30$)
Option #2 Antennas Direct DB8 (84$), PA-18 Pre-amp (43$) and mount kit (17$)
Difference of 102$ not including taxes

Does Channel Master's quality justify paying up the difference? Or would AD be just as good?

I'm leaning towards buying an Antennas Direct today. My options are: DB4, Db8 or a CS 2.

Is a CS2 similar in performance compared to a DB4? Also, how well does a Db8 do for VHF-high channels?

I'm somewhat leaning towards a DB8, depsite a DB4 doing the job, due to fuure conversion channels (both US and Canada)

TVfool: http://www.tvfool.com/?option=com_wrapper&Itemid=29&q=id%3dcef3b76346918e

Cheers, K!

Is a CS2 similar in performance compared to a DB4?

The C2 is most similar to the DB2. I like the C2 better as my personal preference of the two. The DB4 has the same horizontal beam width as the DB2 but has greater gain due to the effect of stacking vertically.

Also, how well does a Db8 do for VHF-high channels?

Short-range, at best, on high VHF.

Is a CS2 similar in performance compared to a DB4?

No, I would say the CS-2 is more comparable to the DB-2 (between the two I would recommend the CS-2 though). The CS-4 is more comparable to the DB-4 (though I would say the CS-4 is probably a bit better).

Also, how well does a Db8 do for VHF-high channels?

Not that well (the same as or worse than tuned rabbit ears). Might be good enough for strong stations, but you will want a separate VHF-HI antenna if you want a chance of pulling in WVNY.

Personally, I would avoid the DB-8. There are better options out there if you want a high gain UHF antenna.

Hey Roger, I've heard the DB-8 is not bad- second only to the 91xg.

Must be a sale on the Antenna Craft stuff. According to their website, the DB8 is going for $119 (same price as a 4228). Or is what your buying a refurb one...even that is still cheaper than what they indicate on their site ($89.25).

The pre-amp differences is that the CM has separate UHF and VHF inputs if you decided to go that route, and may want to dedicate specific inputs for your antenna setup. It also incorporates a FM trap, which I didn't see defined in the PA18 specs. It is also rated at over 20dB for either UHF (26dB) or VHF (23dB), though its noise figure is slightly higher at 2.2dB compared to the PA18 1.8dB. Does that justify the cost increase...only you can decide for your specific location/setup as to which amp would work better.

What type of mounting kit? A "J" mount, tripod, chimney?

Personally, either antenna would most likely work just as well as the other. I think the gain specs of the DB8 are a little bit better, but gain does not paint the whole picture for your particular setup.

As for the amps, the CM7777 is a tested and reviewed pre-amp. Many have written about it here on DHC and back up its capabilities. Not to sure about the PA18...not knocking it in the least. Boils down to if you need the extra amplification in your particular setup, your ultimate goals, and what exactly is being broadcasted in your area.

*EDIT*
Interesting, Antenna Direct website indicates their PA-18 has a noise figure of 1.8dB, but reading on this site and others are indicating a NF of 2.8dB. Wonder which version the store is selling?

Hey Roger, I've heard the DB-8 is not bad- second only to the 91xg.

Where did you hear that? According to Ken Nist of HDTV Primer, when redesigning the DB-8, Antenna's Direct killed its performance and he says that unlike the redesign of the CM4228, there isn't much you can do to fix it. As a result, for most channels, both the HD-8800 and the CM4228 (even unhacked) outperform the DB-8.

Where did you hear that? According to Ken Nist of HDTV Primer, when redesigning the DB-8, Antenna's Direct killed its performance and he says that unlike the redesign of the CM4228, there isn't much you can do to fix it. As a result, for most channels, both the HD-8800 and the CM4228 (even unhacked) outperform the DB-8.

Sigh.. Mr. Nist's opinions certainly get a lot of replay with little critical scrutiny... Our own simulations and lab tests from that time suggest quite the contrary. In any event, it will likely soon become a moot point as the market progresses. BTW, since Mr Nist hasn't updated his site in almost a year, one wonders if he's doing okay...

Live comparative field testing by enthusiast Tom Ballister (antennahacks) also provides a different viewpoint.

We can "lab-test" the efficiency of an antenna by performing "return loss" (S11) measurements with a VNA and a return loss bridge. In general, the more negative the return loss value measured, the greater the efficiency of the antenna. The S11 measurements of the "New" vs the "Old" DB8 does show a marked improvement in S11. S11 values can easily be translated into the more commonly used units of a VSWR ratio. I can supply the test plot if you'd like to see it, by I don't have attachment posting privileges.

*EDIT*
Interesting, Antenna Direct website indicates their PA-18 has a noise figure of 1.8dB, but reading on this site and others are indicating a NF of 2.8dB. Wonder which version the store is selling?

The NF is printed right on the label of the amplifier module (slide the cover open). Older ones say "2.8 dB NF", newer ones say "1.8 dB NF". Performance enhancements were made back last winter.

The NF is printed right on the label of the amplifier module (slide the cover open). Older ones say "2.8 dB NF", newer ones say "1.8 dB NF". Performance enhancements were made back last winter.
Exactly, I wonder if the store he's been looking at are selling the older version...which in his case, he may as well spend the extra money on a new one from your site, or fund for the CM. Also depends on the rest of his install...of course.

Sigh.. Mr. Nist's opinions certainly get a lot of replay with little critical scrutiny... Our own simulations and lab tests from that time suggest quite the contrary. In any event, it will likely soon become a moot point as the market progresses. BTW, since Mr Nist hasn't updated his site in almost a year, one wonders if he's doing okay...

Live comparative field testing by enthusiast Tom Ballister (antennahacks) also provides a different viewpoint.

We can "lab-test" the efficiency of an antenna by performing "return loss" (S11) measurements with a VNA and a return loss bridge. In general, the more negative the return loss value measured, the greater the efficiency of the antenna. The S11 measurements of the "New" vs the "Old" DB8 does show a marked improvement in S11. S11 values can easily be translated into the more commonly used units of a VSWR ratio. I can supply the test plot if you'd like to see it, by I don't have attachment posting privileges.
I've installed quite a few DB-8's, once, I even took a 4228HD down and replaced it with a DB-8. Out of the box, the DB-8 definatley beats the 4228HD. I've only done the hack once, at a clients request, with 2 RCA baluns and a CM 3212 combiner. It worked good, but i didn't have anything to compare it to at the time.
One item to note on the DB-8, I've never seen one correctly assembled by a client. About 5 times the client took it home to 'try it out', before i get there to install it. I always have to turn the screws around, fix the clamps, straighten it out, etc. I've even see some with the cossover connector cables touching the vertical support bar. I always bend them out a bit for clearance.
And the old boots were awfully useless. The newest ones come with a much better connector boot.

I have a question for 91XG owners. On the back segment of the antenna there is a stationary element that is pre-installed. (Right in front of the balun) Out of the 3 that I have used, 2 of them had that element bent in a way that looked like it was done that way on purpose, so I left them that way. I got a new one & that element is perfectly straight. I'm now wondering which is correct & if it really makes much difference either way since it already works so well bent?

Thanks in advance!!
Glen

I'm now wondering which is correct & if it really makes much difference either way since it already works so well bent?

It really doesn't matter...

My understanding, is that the 91XG has the higher rated gain- 15.7db, compared to the single CS4 (12.2), but what about a stack of CS4s?

1) The 15.7 number for the 91XG is for the high UHF range (> 40); low to mid UHF, the dbs would be lower (12ish?).

2) When stacking the CS4s there should be a net gain of about 2.5 dbs, for a total 14+ dbs, no?

3) AD says the 12.2 number for the CS4 is across the entire UHF band. So at low to mid UHF the stack of CS4s might be better than the single 91XG?