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post #1 of 39 (permalink) Old 2017-03-18, 03:31 PM Thread Starter
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4 bay antenna question

For some reason with my new Moniker I can't use the Search function. As a result I am going to have to ask for some help on this despite the fact it has probably already been posted here.

In my current home I have been using a Super G 1483 8 bay. Works well. But it is probably overkill for my situation and better suited to receiving Deep Fringe signals.

** TV Fool

I'm receiving every channel down to Ch. 26. Happy with that. Using a RCA pre amp I am getting pretty good signals of about 20 db snr readings on the TV SS meter.

I'd like to use a 4 bay instead because then I will be able to add a Delhi VIP 302 VHF antenna to use for Dxing. Will mount both antennas on a rotor. Have limited space and can't really use a Yagi style antenna or large UNF/VHF either. Have those sitting in the cellar when the day comes that I have a larger property and house.

According to the repack info I am seeing most of the Dayton channels I want to receive (all in red on the report) will be in the 30 to 36 channel range. With that in mind, and using a preamp which 4 bay has the best reception of channels in that range? Ch. 45 likely won't come in right now but maybe after it changes to Ch. 36 in a few years I will have a shot at it.

And, would I be better off trying a different preamp than the RCA? It is not overloading at all but I think I've read there are other preamps available that offer a little more gain in strong signal areas while not prone to overload.

Any suggestions?
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post #2 of 39 (permalink) Old 2017-03-19, 03:12 PM
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YIKES....I'm surprised to see it working at ALL, being only a few miles from your Local Towers. Intermods must not be affecting ALL of your Weak Signals, but I'm sure it's VERY BAD. With EXTREMELY HIGH INPUT SIGNALS (e.g. -12 dBm PLUS Antenna Gain of ~ 16 dB in Super G-1483 = ~ + 4 dBm), the Intermodulation Distortion Noise will overwhelm Weak Signals using RCA TVPRAMP1 [Max Input = -35.4 dBm for 67 dB Max SFDR]. Although expensive A-D Juice Preamp has MUCH higher Overload Resistance (Max Input = -21.3 dBm for 81.7 dB Max SFDR), it ALSO will be Severely Overloaded. [SFDR = Spurious Free Dynamic Range = Difference between Max Output Signal and Max Noise Floor] Per Actual Preamp/DistroAmp Overload Measurements by Calaveras:
http://photos.imageevent.com/holl_an...028Nov2015.jpg

Why are you using a PREAMP??? Have you tried it with the PREAMP REMOVED [you can't just remove DC Power]. If it turns out that you NEED some Amplification to drive say 8 or more drops, then you would be better off using inexpensive CM341x Series Distribution Amplifier [Max Input = -21.6 dBm for 81.9 dB Max SFDR]....and you should ALSO insert some additional ATTENUATION on it's INPUT [Downlead provides perhaps a couple dB Loss]. For each 1 dB of Input Attenuation, the Third Order Intermods are reduced by 3 dB....hence 3.5 dB Loss (e.g. try inserting an extra RF Splitter on DistroAmp's Input) results in reducing Intermods by 10.5 dB, a Net SNR Gain of 7 dB)....and YOU might need as much as 10 dB Input Loss [Net SNR Gain of 20 dB] since you are TRYING to receive some of those Out-Of-Market Dayton Stations in TVFool's RED Zone.

Changing to a 4-Bay vs Super G-1483 will reduce Antenna Gain mid-band by only about 2.5 dB....which reduces Intermods by 7.5 dB, a Net SNR Improvement of only 5 dB. Compare Modeled Results for Super G-1483 vs CM4221HD):
http://photos.imageevent.com/holl_an...0Gain%2016.jpg
http://photos.imageevent.com/holl_an...Raw%20Gain.jpg

Modeled Performance for A-D DB-4e and CM4221HD are essentially the SAME....and we don't have detailed info (or measurements) for any other current 4-Bay (e.g. inexpensive Solid Signal HDB-4X likely ALSO has about the same Gain):
https://www.antennasdirect.com/cmss_...s/DB4E-TDS.pdf
UHF CM4221HD (Hacked) - 16 ReflRods [NOTE: Balun Assembly flipped for more Separation from Feedlines]
CM4221HD Hardware Hacks - Page 15 - Canadian TV, Computing and Home Theatre Forums

One other Issue: Back in 2007, Low-Rez CECB's (Coupon Eligible Converter Boxes) were REQUIRED to meet fol. Spec. Requirements, which are probably "typical" Minimum Operating Conditions for later model DTV's and OTA STB's:
https://www.ntia.doc.gov/legacy/dtvc...ufacturers.pdf

In NON-FADING Bench Tests, Adjacent Channels as Strong as 33 dB MORE than the Desired Channel "should" be tolerated [e.g Strong Ch29 vs Weak Ch30 for FOX]. And "TABOO" (N +/- 2) Next Adjacent, [ e.g Strong Ch24 and Ch28 vs Weak Ch26 for CW] as Strong as 44 dB MORE "should" also be tolerated. In the REAL-WORLD, the weaker Channels would be suffering from Multipath Fading, whereas the Strong Local LOS Channels would NOT....so I would expect to see Adjacent Channel ISSUES when only about 20 dB Stronger and Next Adjacent Channel ISSUES when only about 30 dB Stronger.

In YOUR Case, Ch29 is 71.6 dB Stronger than FOX on Ch30. And Ch24/28 are 64.9 dB & 64.6 dB Stronger than CW on Ch26. Super G-1483 Antenna Pattern provides only about 10 dB suppression of Ch28 and since they are only Separated by about 36-deg, perhaps 10-15 dB Suppression of Ch24 if you carefully Tweak the Pointing Angle. So I'm very surprised to see that you successfully Receive THE CW on Ch26.....and changing to 4-Bay with provide better suppression of Ch28, however the Wider Beamwidth will make this situation WORSE for Ch24 Suppression vs THE CW on Ch26.
http://imageevent.com/holl_ands/gray...n/acsuperg1483

Mounting the Antenna so that there is SOMETHING between it and your Local Stations can help to suppress those Extremely Strong Signals (such as your House). Adding a LARGE Wire Mesh Screen could also help. And using a specially built DIY Antenna with a DEEP NULL in the Rear Antenna Pattern would help the MOST. I need to do some additional research and perhaps Re-Optimized some Designs before I can recommend anything.....such as fol. PAIR of VERTICALLY Stacked 91XG Yagi's [I NEED to do some RUNS for HORIZONTALLY Stacked 91XG's...and perhaps OTHER, SMALLER UHF Antennas]:

Antenna Simulations, Overload Calculations, etc: http://imageevent.com/holl_ands

Last edited by holl_ands; 2017-03-19 at 04:38 PM.
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post #3 of 39 (permalink) Old 2017-03-19, 03:31 PM Thread Starter
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Hollands. I know this will sound nuts but I tried several antennas at this location with and without the preamp. In every case I've been able to get 2. 7. 16 and 22 from Dayton with the preamp with no discernible impact to the local stations. Everything that should come in here does with the preamp. The only case where this didn't work was with a MXU47 which I believe was defective. Didn't work well even on the local stations without the preamp. Installed my MXU59 in place and it worked well with and without the preamp.

Moving the installation 10 feet east I was able to gain Ch. 26 with the Super G 1483. In light of what you's said I may try my U4000 at this spot just to get an idea if I can still get 2, 7, 16, 22 and 26 with a 4 bay. The U4000 is now my travel antenna and I will use something with more gain in this spot at home to hopefully assure that I will still have reliable reception of these stations without the need for the Super G 1483. Want to put that in storage for the day when I need it for Deep Fringe signals. Irreplaceable just like the CM 4251. Best to save it for when I really need it.
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post #4 of 39 (permalink) Old 2017-03-19, 03:33 PM Thread Starter
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One thing that may be requiring the use of the preamp for better reception is the fact that I am surrounded by tall trees and taller buildings and homes. Urban area only a mile and a half from downtown Cincinnati.
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post #5 of 39 (permalink) Old 2017-03-19, 04:57 PM Thread Starter
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Would using the Winegard LNA-100 along with either the CM 4221 or AD DB4e work in this situation? Writing off Ch. 45 of course but with a rotor I think 2, 7, 16, 22 and 26 will still be received at this location with the right 4 bay and preamp. Gave some thought to the Televes DAT 790 MIX with VHF and long range UHF but decided that might be an issue if I have to mount it on the roof due to tree limbs on the adjacent property.
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post #6 of 39 (permalink) Old 2017-03-19, 05:22 PM Thread Starter
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I actually tried the Balun flip on a pair of CM 4221 HD's that I had about 7 years ago. Also took out the end caps. It helped on some channels but on others I didn't see any improvement.

Judging by the links to the data you've posted on your site, it appears the DB4e and CM 4221 perform nearly identical on the channels in the 30 plus range. Just a matter of determining which preamp is best here provided that I still need one. Probably will based upon all past tests here.
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post #7 of 39 (permalink) Old 2017-03-19, 06:05 PM
 
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Nice location!

I bet stripped coax or a paper clip might work.
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post #8 of 39 (permalink) Old 2017-03-19, 06:22 PM Thread Starter
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dss. For local signals that is correct. Have tried a small wire and I do pick up a few local signals. But to obtain the Dayton signals I need to use a little more antenna.:-)
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post #9 of 39 (permalink) Old 2017-03-19, 07:10 PM
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Another, "PERHAPS" Better Alternative: I just Uploaded Results and Detailed Dimensional Drawings for fabricating a REPLACEMENT Holl_ands Horizontal Harness (HHH) for the CM4228HD 8-Bay Bowtie Antenna. The Narrower BEAMWIDTH, as well as high UHF Gain may help in suppressing Ch24 vs The CW on Ch26. With these new HHH Dimensions, it now ALSO provides CONSISTENTLY FORWARD, High Gain in the Hi-VHF Band with Very LOW SWR....so it's now a COMBO Hi-VHF/UHF Antenna....the HOLY GRAIL of 8-Bay Bowties....and is only 31.5-in High vs 61.5-in for Super G-1483:
CM4228HD Hardware Hacks

=========================================
FYI: Antennacraft U-4000 has about SAME Raw Gain in Mid-UHF Band as other 4-Bay Bowtie Antennas....but only about 12 dB F/R Ratio [Ratio between Gain Directly FORWARD and Highest Gain towards the Rear Hemisphere] and about 15 db F/B Ratio [meaning it has a SHALLOW NULL DIRECTLY towards the BACK, i.e. Exactly 180-deg from Forward]....but Suppression of Ch29 will be more difficult to Much Wider Beamwidth:





=========================================
FYI: W-G HD-4400 actually has about 1.5 dB HIGHER Raw Gain in Mid-UHF Band....and MUCH BETTER F/B Ratio ~ 27 dB and F/R Ratio ~ 15 dB....but Suppression of Ch29 will be more difficult to Much Wider Beamwidth:
W-G HD-4400 4-Bay Dipole with Reflector




Antenna Simulations, Overload Calculations, etc: http://imageevent.com/holl_ands

Last edited by holl_ands; 2017-03-20 at 05:11 AM.
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post #10 of 39 (permalink) Old 2017-03-19, 09:15 PM Thread Starter
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Hollands. If I am reading you correctly, the Antennacraft U4000 has better gain in this channel range than the CM 4221? And the Front to Back Ratio is also superior? What is a F/R Ratio? Or do you mean the Winegard 4400? I have a U4000 but don't have the Winegard. Not sure if I can still find either antenna but I could give it a shot.

My primary concern with using a 8 Bay like the 4228HD or a similar antenna is the weight. It weighs around 10 lbs. The VIP 302sr weighs 6 lbs. Installing those on the rotors that I own (Antennacraft TD2P, NTE U106) will likely result in gears being stripped due to the weight. And I am also concerned about the mast I am using which is standard 1 and 1/4 inch which is going to be attached to a 5 foot mast which is planted in the ground. I am going to build a base of cinder blocks and cement which will be a couple of feet high and will secure the base. But I just don't see how that much weight on a standard rotor will keep either rotor from falling apart. No room to guy anything and I can't install a free standing tower since I could not find anything at that height. And even if I could, due to the puny yard I have it would present issues with a Part 15 AM radio transmitter I intend to install near it and also a weather station.
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post #11 of 39 (permalink) Old 2017-03-19, 09:24 PM Thread Starter
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Hollands. Took a look at your HHH. Do you have any actual photographs of it online? Not sure I have the tools needed to put this together. I don't have a soldering gun though I suppose I could buy one. But again my main concern is the weight. I want the VHF low of the Delhi antenna to use for DXing and also FM reception.

If I can dig up a Winegard 4400 4 bay would that be better than hacking a CM 4221 HD for channels 30 to 36?
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post #12 of 39 (permalink) Old 2017-03-20, 05:17 AM
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I fixed my earlier post re. Alternative 4-Bays.....sorry about the confused Part Number problem.....

===================================================
I just weighed myself with and without CM4228HD....it only weighs 4.6-lbs......perhaps 10-lbs is the SHIPPING WEIGHT, incl. the Cardboard Box....and perhaps an even bigger box around THAT. [BTW: A Half-Gallon Carton of Milk weights 4.3 lbs.]

IF you chose to use JUST the CM4228HD with the HHH that turns in into a COMBO Hi-VHF/UHF Antenna, then you wouldn't NEED any other Antenna. Note that there are THREE versions of interest: Alt(b) requires new HHH plus Replacing Brackets between Bowties and Reflectors, Alt(b) ALSO requires Wider Extensions to ALL Reflector Rods whereas Alt(c) ALSO requires Wider Extensions to every OTHER Reflector Rod:
http://imageevent.com/holl_ands/mult...8hdhhhtsrsyrod

BTW: Your Ch12 is very strong and hence you MIGHT receive it with an UNMODIFIED CM4228HD...or at most with Alt(b) COMBO Hi-VHF/UHF Mod Kit [HHH with new Cylindrical Balun plus new Bowtie-to-Reflector Brackets, with NO Changes to Reflector Rods].

Although I REALLY don't want to get into PERSONALLY Fabricating Antennas for other people....or even Mod Kits, but if it helps [and I have yet to Fabricate MY OWN Mod Kits for all 3 NEW Versions], I'll be happy to make you a ONE TIME OFFER to MAKE and SHIP you a set of new Brackets between Bowties and Reflectors plus a Pre-Fabricated HHH with Balun that can be attached to the Antenna's Reflector [using Tie-Wraps or whatever].....which will allow you to implement Alt(b)....which is probably overkill to receive your Ch12. Note that SOME versions of the CM4228HD will require drilling out four Rivets and replacing them with Screw/Bolts....it's been a few years, but I THINK mine had Screw/Bolts to begin with....

Antenna Simulations, Overload Calculations, etc: http://imageevent.com/holl_ands

Last edited by holl_ands; 2017-03-20 at 05:51 AM.
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post #13 of 39 (permalink) Old 2017-03-20, 07:56 AM Thread Starter
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Hollands. Thanks for the additional info. If the weight is only about 6 lbs. that should be OK. A installation setup with a Winegard HD7084 which weighed around 11 to 12 lbs. worked out OK with both rotors. I figure that anything with more weight would be a problem.

I have to go to work and I am gone from 9 AM until 10:30 to 11 PM at night on average. I will get back to this over the weekend and let you know.

What kind of gain will I see on VHF Hi with the modified and unmodified 4228? Will it equal VHF Hi on the Delhi 302sr? I would like to have VHF Low for DXing purposes and also for FM reception.
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post #14 of 39 (permalink) Old 2017-03-20, 04:15 PM
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I added CM4228HD Performance Comparison Charts for various Alternative HHH's in fol. post....and Dimensional Diagrams in subsequent post:
CM4228HD Hardware Hacks

I couldn't find info for Wade/Delphi VIP-302SR on-line....but I do have a copy of the "VIP and ZIP Antenna" Spec Sheet.
Lo-VHF Gain ~ 4 dBd = 6.2 dBi and Hi-VHF Gain ~ 8 dBd = 10.2 dBi.....these may be MAX spec numbers rather than "typical".....

Compare to CM4228HD which has Hi-VHF Gain ~ 8.5 dbi +/- 0.5 dB for MOST Alternatives [so MAX = 9.0 dBi], whereas Alt(b) and Alt(c) drop down to as low as 7.0 dBi on Ch10/11.

So you probably want to use [4.6-lb] CM4228HD [with UHF-ONLY Version HHH] in addition to your [6-lb] VIP-302SR.

Antenna Simulations, Overload Calculations, etc: http://imageevent.com/holl_ands

Last edited by holl_ands; 2017-03-20 at 05:28 PM.
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post #15 of 39 (permalink) Old 2017-03-21, 08:06 AM Thread Starter
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Thanks Hollands. I will have time to look at the links this weekend. Knowing that the 4228 weighs around 5 lbs. makes this an easier decision. Will very likely go that route.

How much do you want for the HHH plus shipping?
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