Thanks for confirmation, sounds promising. I have 70-75° or 95° if I try for ION, will have to check the contour vs tvfool and see how well it might work.
As the expected dB counts suggested, excellent results with the DB4e. Receiving everything nicely except the weaker VHF stations.

Kinda wish I had a CM4221HD to do direct comparison.
I can say it performs better than the no name 4-bay, though that doesn't mean much with the terrible build quality that was.

missing 1 out of 4 screws for the combiner bars.

The empty hole in the back of the balun box is normal. Every one I've seen has been like that and a check with AD's tech support a while back confirmed it.

Solid Signal's website even has a photo that highlights this. See http://www.solidsignal.com/pview.asp?p=DB8&d=Antennas-Direct-DB8-UHF-HDTV-TV-Bowtie-Antenna-%28DB8%29&sku=853748001088

Rearanged my antenna. Now I'm picking up MeTV (12.1) and CoolTV (12.2) in addition to everything else. The antenna is pointed straight north. All the stations except physical 35 virtual 12.x are picked up by the rear of the antenna via the two lobes on the left and right on the gain graph:
http://leszek.smugmug.com/Electronics/Satellite/Satellilte/i-wnZksp8/0/O/db4es.jpg

http://leszek.smugmug.com/Electronics/Satellite/Satellilte/i-4Nc2ktp/0/O/TVFOOL.jpg

So remember, sometimes it's better to use the rear instead of the front of an antenna. ;)

@ProjectSHO89:

thanks for the reply! i'm a bit more reassured now, though i wonder why:

(1) solidsignal's image for the balun did not come up in all my googling for such an image, and

(2) why they are pointing out the "missing" screw... without any explanation that i can see.

all of this being said, the hoped-for improvement in getting wcfe pbs did not materialize and confirmed that there is only so much you can "get" from an attic mount. as soon as it warms up, my new antenna is going on a j-mount on the roof!

cheers!

I have a question for AD Tech. In a previous post, you mentioned that the CV2E VHF kit could be used with other Antenna's. Can I expect any improvement in VHF performance if I mount it to A DB8? Or is it even doable? Thanks. F.T.

I have a question for AD Tech. In a previous post, you mentioned that the CV2E VHF kit could be used with other Antenna's. Can I expect any improvement in VHF performance if I mount it to A DB8? Or is it even doable? Thanks. F.T.

Sure, it's doable. I've installed the dipole on all of our loop and bowtie antennas.

On a DB8, an easy location is to put in on one of the half-panels similar to the way it was installed on the DB4e in post # 371. However, this placement is far from optimal as half the dipole will be in there with the combiner assembly and the cross-bar. It's a poor location but it will perform better than the stock DB8 on high-VHF. A better location for the dipole is to put it above the reflector screen on one side or the other. You'd need to do some basic cutting and drilling to make a more universal add-on as shown in post 294. You'd also need a coax cable that's a bit longer, perhaps 24" or so. I suppose you could also just remove the reflector and use the included mast clamp to attach the dipole to the mast. You'd probably have to get longer coax jumper cables.

Keep in mind that adding a simple VHF dipole to a "long range" UHF antenna is often like putting a 14" wheel on a pickup truck along with three 17" wheels - something isn't going to match well. Usually, if you need the gain and directionality of a DB8, you will also need a more substantial antenna for VHF reception than a simple dipole will offer.

Cheers!

Usually, if you need the gain and directionality of a DB8, you will also need a more substantial antenna for VHF reception than a simple dipole will offer.

I certainly agree that you need to properly evaluate what you need before buying any antenna. Things are a bit different for many people here in Canada than it is in the US though, as those in/near big cities can easily pick up all the locals with a low gain antenna, but there is a strong desire to also receive distant US stations. As a result people will buy a high gain antenna, point it "south" and hope it will also receive all the locals on the side/back.

This can work for local UHF channels, but often won't work for local VHF stations. Adding a dipole can fix the problem, but in that case, mast mounting the dipole would likely be best so that it can be aimed towards the local transmitter for optimal reception.

Having said that, if there are distant VHF stations, a better VHF antenna will certainly be necessary to receive them.

balm, it all depends the channel and how strong the transmitter is. The C2 has a gain of between -40 and -60 dBd on VHF-HI (depending on the channel) so unless it is very strong, your results won't be very good. The C4 ranges from 0 to -20dBd, so you might be more successful with it, but it has a much narrower beamwidth. Either way you would be better off adding the VHF kit.

Hello Balm,

my C2 picks up CTV 12.1 and TV 10.1 at about 60-70% from Pointe-Claire (outdoor chimney mount about 30ft off the ground). It did not pick up the signal when I tested it from the interior of my house. TVA was harder to get than CTV.

If you want a more sturdy reception signal you need to go for the C2 Complete with the VHF dipoles

Thanks guys,


Thats too close to call, the NMs are in 60's, so there wont be much margin left - I think I'll try a simple 2-bay wich will receive these VHF-Hi

do the clearstreams C2, or C4 pick up strong VHF-Hi channels (within 10 miles) ?

The correct answer is "They're highly variable". We get anecdotal reports of varying levels of success. I've done enough field testing to know that predictability is important, though.

The C4 will usually do a bit better than the C2, but I've found that neither offers a level of predictability that would allow me to suggest them for VHF applications with confidence. Some lessons are learned the hard way...

That said, both antennas allow a limited amount of reception using somewhat the same mechanism as a Walkman or a bedside clock radio uses for an FM antenna - the cord. Now, I've "cheated" with a spectrum analyzer first, but I've been able to receive VHF at more than 50 miles with a C2. However, my way of doing it isn't practical for someone without the test equipment.

Therefore, my usual advice is to either make specific plans for VHF or to be prepared to either experiment or to accept whatever VHF happens with the UHF design.


The C2 has a gain of between -40 and -60 dBd on VHF-HI (depending on the channel) so unless it is very strong, your results won't be very good. The C4 ranges from 0 to -20dBd, so you might be more successful with it, but it has a much narrower beamwidth.

Those numbers would appear to be from Nist's modelling. My field testing has shown that those numbers don't (they simply cannot) account for the feedline radiation mechanism by which the antennas pick up VHF.

With an NM in the 60's for VHF, my inclination would be to say that it will most likely work okay anyway.

Does anyone know of a test between the DB4e against the DB8 version? Thanks.

Question for ADTech:

In order to balance better the channel received from the front of the DB4e antenna with the channels received from the rear, I lowered the upper screen exposing the top most element to the rear:
http://leszek.smugmug.com/Electronics/Satellite/Satellilte/i-dQb6pzq/0/O/MG0698.jpg

This seems to balance my weakest station in the front of the antenna RF35 71 miles away with my weakest station in the rear of the antenna RF27 33 miles away:
http://leszek.smugmug.com/Electronics/Satellite/Satellilte/i-3Kg9Bqf/0/S/27-S.jpghttp://leszek.smugmug.com/Electronics/Satellite/Satellilte/i-dCcGmhW/0/S/35-S.jpg

So overall this is working, but I'm very curious what exactly does this do to the gain characteristics of the antenna? And is that a good way of receiving stations that happen to be almost 180 deg away from each other. (as per my TVFool report link in my previous post above)

Thank you!
Leszek

After a couple of months of experimenting with my Digitenna DF and Antennacraft HBU33 on my outdoor mast, I've re-installed the 91XG for DX season.
WOW! I had forgotten how much of a stone-cold killer the 91 is. Co-channels fade away. 120-mile stations show up briefly even with no tropo activity. Super-weak low-powers suddenly roar to life. Signal meters stay pegged at 100 as if they were nailed there with a Paslode.
I'm not sure why I bother fooling around with anything else.

Have you built an M4 or M8 to compare against your 91XG?

I built M4 and it was okay to get 140km stations with NM -8dB or worse on tropo days... then added a 2nd M4 to make it an M8 and I can get those stations locked for a little longer, even on wet days... not reliable, but just a little longer the channel comes in more often on non-tropo days than with just M4.... wondering if I should order 91XG to try out...

lithOTA, your findings aren't surprising since you are comparing medium gain antennas with an ultra high gain antenna. It is kind of like trying to compare fuel efficiency by seeing how far you can drive on a tank of gas when one car has a bigger gas tank.

^^^^
Well, of course, 22 directors is better than 10. I just forgot HOW much better.

Have you built an M4 or M8 to compare against your 91XG?

I built M4 and it was okay to get 140km stations with NM -8dB or worse on tropo days... then added a 2nd M4 to make it an M8 and I can get those stations locked for a little longer, even on wet days... not reliable, but just a little longer the channel comes in more often on non-tropo days than with just M4.... wondering if I should order 91XG to try out...
I have built a few M4s and GHs, but my fabrication skills aren't very good. I have seen specs on the M8 that are stellar, but multi-dipole panel antennas won't work as well at my location (CM4228 included). This is because I have numerous co-channels among my local stations, and there are 10 TV markets within 150 miles, so there is always a co-channel around to ugly up the signal (for example, there are 4 full-power RF 19s). The 91XG has such a laser-beam pattern (especially at higher freqs) that it really locks out those offending co-channels.

Has anyone thought of removing the red plastic from the bowties on the DB4e antenna? I'm wondering if this might increase its gain.

No, it won't. They're just spacers and have zero effect on reception.