CM4228HD vs HD7698P - Bow-tie vs Yaggi?

[kenj66]

I live in an area with almost exclusive 2Edge signals. I'm not happy with my present system so I am likely replacing my 91XG with a Wineguard HD7698P which is a deep fringe yaggi. I'll pick up additional Seattle channels 9 and 11 on Hi-vhf and use the 91XG to pick up the local channel 7 repeater since channel 7 out of Seattle never really worked well for me.

I recall reading an experienced poster here on the forum who recently claimed that these deep fringe antennas need more surface area to overcome signal dropout problems. Is that true? I have lots of dropout problems!

If so perhaps I should consider the change to an 8 bay bow-tie such as the Channel Master CM4228HD that 'teleview' recommended to me or a DB8.

Ken

[ADTech]

You will find that the 91XG will outperform the 7698 on UHF (it has no expectation of VHF performance, use a separate VHF antenna for that). The 91XG has higher gain, greater F/B ratio, and a narrower beamwidth bay almost half.

You do realize the 7698 is 14' long, don't you?

Is that true? I have lots of dropout problems!

It's a lot more complicated than that. Perhaps it would be best if the reason for the dropouts was identified so that an solution might be investigated.

[kenj66]

Hey, ADTech, I can always count on a healthy dose of reality coming from you! Thanks for weighing in.

Originally Posted by ADTech

the 7698 on UHF (it has no expectation of VHF performance).

You do realize the 7698 is 14' long, don't you?

Perhaps it would be best if the reason for the dropouts was identified so that an solution might be investigated.

An antenna with a 14 foot boom has little expectation of gain? Really?

Since I removed the PCT preamp the random stuttering on 100 percent signals has stopped. And channel 7 (39) has completely dropped out.

It is difficult to assess the relative performance of various antennas. Some have claimed/measured performance figures; some don't. I was very surprised to find the DB8 has a claimed gain of around 17 dBi. Having some background in antenna theory it is hard to believe that 8 wideband dipoles mounted on a simple reflector could have that much performance. They used to call those "bedspring antennas." I know they have a very wide beamwidth so I was wondering about the claims for more signal stability due to the larger reflector capture area.

I had thought about getting a combined vhf-hi/uhf to pick up Seattle 9 and 11 since they transmit from the same area on Queen Anne Hill and it was clear that I needed a second antenna anyway. If the CM4228HD or DB8 is not the appropriate antenna for my situation then I suppose I could forget 9 and 11 and get a 42XG to pick up the channel 7 (26) repeater which is nearly 180 degrees from from the Seattle heading.

I appreciate your experience in these matters.

Ken

[ADTech]

An antenna with a 14 foot boom has little expectation of gain? Really?

You cannot fully compare a UHF-only antenna with a U/V combo antenna. The 7698 is, in reality, two antennas that are assembled nose-to-tail. Only the front end of the 7698 is comparable to the 91XG and that's on UHF only. The back part of the 7698 is for high-VHF which is not a part of the 91XG's design. Combo antennas, by their very nature, represent a set of compromises while a single band antenna does not.

a combined vhf-hi/uhf to pick up Seattle 9 and 11

You're usually better off using a separate high-VHF antenna combine with a UHF antenna. That allows you the flexibility of putting each antenna where it really works best, locations which may not be in the same place for UHF or VHF.

I was very surprised to find the DB8 has a claimed gain of around 17 dBi

That would be the re-scaled DB8e, not the older DB8. The older antenna's gain peaked up in what is now the cellular bands. By rescaling the antenna, the peak gain moved down into the current UHF band and bumped those numbers up by an average of 2-3 dB gain improvement.

I know they have a very wide beamwidth

Actually, they are the opposite (very narrow beamwidth), not much different from UHF Yagi antennas as far as half-power beam widths go. Nulls and the side/back lobes tend to be quite different, though, from a comparable Yagi.

[kenj66]

Originally Posted by ADTech

You cannot fully compare a UHF-only antenna with a U/V combo antenna. The 7698 is, in reality, two antennas that are assembled nose-to-tail. Only the front end of the 7698 is comparable to the 91XG and that's on UHF only. The back part of the 7698 is for high-VHF which is not a part of the 91XG's design. Combo antennas, by their very nature, represent a set of compromises while a single band antenna does not.

You're usually better off using a separate high-VHF antenna combine with a UHF antenna. That allows you the flexibility of putting each antenna where it really works best, locations which may not be in the same place for UHF or VHF.

Yes, I understand the nature of the compromise in that design. However, with a 14 foot boom, by all observation it would appear to overcome that compromise. What I hear you saying is apparently not, at least not enough to make it worthwhile.

I cannot support three antennas. Seattle and the Silverdale repeater are opposite one another in my location so I will have to forgo the hi-vhf channels. The 91XG is a very impressive performer and I will keep it. Thank you for helping me make this decision.

[ADTech]

However, with a 14 foot boom, by all observation it would appear to overcome that compromise.

You're basically taking a 7' UHF antenna and placing it on the end of a 7+' VHF antenna. The length that comprises only the VHF antenna section is irrelevant for the UHF antenna section. Note that some of the UHF section does double duty by including VHF elements, otherwise the VHF section would approach 8-10' in length.

Adding a high-V antenna to the 91XG would be your best bet for the VHF stations.

I find it's helpful to think in real estate terms for a rough analogy. A 2000 sq ft ranch has the same square footage as a two-story house with 1000 sq ft on each floor. One big floor vs two smaller floors vertically stacked, about the same square footage.

[kenj66]

Originally Posted by ADTech

Adding a high-V antenna to the 91XG would be your best bet for the VHF stations.

High-V I'm not familiar with that term.

Ken

Oh, perhaps you meant high-vhf. How could I support three antennas?

[Flint Ridge]

Hi- VHF (Ch 7-13) does not cover Lo-VHF (Ch. 2-6)

The 91XG is tiny compared to the 14' Winegard. Very impressive for its size.

[kenj66]

You will find additional discussion in another topic Difficult location 15 miles west of Seattle The 91XG is over 7 and a half feet long!

My priority for picking up additional stations is first channel 7, then 9 and then 11. Channels 9 and 11 are holding their original channel assignments in the high-vhf band. Since they have transmitter/towers in the same area on Queen Anne Hill in Seattle it seemed like it would be easy to add them with a bigger antenna covering both high-vhf and uhf.

However, I have still been plagued with occasional stuttering on most other stations. It was difficult to pin down the culprit since our commercial TVs are known to have questionable signal handling quality because manufacturers know that 95 percent (or more) people now use cable TV. I have been using a PCT TV preamp and yesterday I removed it from the system. I lost channel 7 but - the stuttering stopped! So, I fine tuned the position of the 91XG and found I could occasionally pick channel 7 but it was not watchable.

Thinking some more, I remembered I had tweaked the PCT MA-B1015-1A-VG preamp for maximum gain. Could this be the problem? So, I replaced the PCT and reduce the gain to its minimum. Channel 7 was stuttering but more watchable. With the PCT back in the system almost all the other channels now had the occasional stuttering again which means this preamp is likely suffering from some sort of intermodulation distortion.

My conclusion is that either I got a bad PCT or channel 13 is just too close and will saturate the front end of any preamp I use. I do have an article that tells how to make a tuned stub filter and I am thinking of making one just for channel 13

For now I will be content to forgo 7, 9 and 11. I still have 4, 5, 13, 16, 20 and 22. Not so bad. Peace!

Ken

[ADTech]

For an inexpensive ch 13 attenuator, get one of these: http://www.channelmasterstore.com/JO..._p/cm-0583.htm Put a terminator on the ch 13 input and run the signal trough the Jointenna.

You also have a very strong UHF 14 coming in off the back of the antenna. If you can find one, a Channel Plus NF-469 will cool it off a lot.

The gain control on that amp is irrelevant. It's only for the active return path which is not used in an OTA application. It's actually a drop or distribution amp intended for cable TV applications, it's not a preamp.

[kenj66]

Originally Posted by ADTech

The gain control on that amp is irrelevant. It's only for the active return path which is not used in an OTA application. It's actually a drop or distribution amp intended for cable TV applications, it's not a preamp.

I reread the spec sheet on the PCT. They want to make sure you don't have unrealistic expectations for what it can do. If it is not really a preamp then why does it have a remote power inserter? Also, this model has gain adjustments for both forward and reverse gain.

I am considering the TVPRAMP1R and 42XG to pick up the channel 7 (26) repeater.

Originally Posted by ADTech

For an inexpensive ch 13 attenuator, get one of these: http://www.channelmasterstore.com/JO..._p/cm-0583.htm Put a terminator on the ch 13 input and run the signal trough the Jointenna.

You also have a very strong UHF 14 coming in off the back of the antenna. If you can find one, a Channel Plus NF-469 will cool it off a lot.

Thanks. Ordered both. Fifteen years ago when I tried setting up an antenna system in my former location I found single channel inline traps available on line. They have disappeared from the marketplace. The two items you recommended are marked as closeout and seem to be in short supply. This seems shortsighted since more people now are cutting the cord, as they say. I would expect more demand for such items to help solve these problems.

Ken