: Stacking, Ganging, Combining TV Antennas
2012-03-02, 07:40 AM
Selected VHF Jointennas are still available on ebay. A Jointenna will interfere with a channel 12 signal.
If channel 13 is the only VHF signal of interest in your area, a UVSJ is fine.
so having the 4228HD on the UHF port (of the UVSJ) wont cause problems on the 4228HD receiving #10, #12....?
If not , if #12 is still strong, wont #12 still swamp #13, on the other hand, #12 would probably be picked up anyway by the #13 yagi....
2012-03-02, 10:16 AM
balum, cut channel Yagis will receive channels slightly lower than the target reasonably well, but won't receive higher channels very well, so a channel 13 Yagi should also be able to pick up 12 and maybe even 10 (depending on the direction it is aimed of course).
A UVSJ will filter out all VHF channels from the UHF port and all UHF channels from the VHF port. A Jointenna will badly distort adjacent channels and likely make them un-receivable so I wouldn't use one for channel 13 if you also want channel 12.
BTW, in Montreal now that channel 12 is digital, it shouldn't cause as many problems with channel 13 as it did when it was analog.
so a channel 13 Yagi should also be able to pick up 12 and maybe even 10 (depending on the direction it is aimed of course).
thats the problem, the yagi will aim at Vermont for #13, I DONT want it for #10, #12, from Montreal, which are at 84 degrees from #13. I thought to reduce interference between the 2 antennas on VHF, a UVSJ needs to be used, but then it will also reduce desired Montreal #10, #12 received on the UHF antenna (CM4228HD).
Maybe I'm not explaining myself adequtely...
2012-03-02, 11:46 AM
Any chance you could use separate tuners? I did that in my HTPC, that was I could dedicate antennas to the states, and one for canada...
no, im not setup with a computer, so i was thinking of an A/B switch to change between antennas manually
2012-03-02, 12:02 PM
Yeah, that or a rotor for the VHF-Hi. Trouble with an A/B switch is if you want to amplify all antennas. I suppose you could put a pre-amp on both and just switch an amplified signal.
i might try using the #13 join-tenna, put the CM4228 on the ALL port, and the yagi on the #13 port, this should help #13 on the yagi, and not reduce #10, #12, too much on the CM4228Hd...im not too sure :confused:
2012-03-02, 02:17 PM
I use a channel 9 jointenna and still receive channel 8 just fine, with essentially no reduction in signal strength on either station. Perhaps a channel 13 jointenna would work just as well for you. There's an ebay store listing "More than 10 available" right now (can't post the link); not too expensive to try it.
can you give me an idea of your set-up, what antennas pointed where to receive which channels please...thanks
EDIT: i see channelmaster store removed the jointennas from products!
EDIT : I think the rotor, or the A/B switch are a problem cause of multiple TVs, the A/B switch being the worst....unless I'm missing something...
2012-03-02, 06:39 PM
Keep in mind that a channel 13 Jointenna will have its roll-off in channel 12. If your tuner can handle it, you're fine.
So if I put a VHF-Hi yagi (For #10, #12, #13) on a rotor, how far above the CM4228HD on the 3 ft tripod, do I need to go, if its even possible (structurally) ...the 2 antennas will be combined.
2012-03-03, 02:00 PM
I am considering planting a mast on the peak of my roof to relocate my existing AntennaCraft U8000 8bay antenna, then also attach a CPE from a wireless internet provider on the top of the same mast.
If I use a tripod, 10 foot mast, 5 feet of mast above the tripod, this would put the CPE approximately 1.5 to 2 feet above the top of the 8 bay antenna.
I should have no more than 15-20 pounds of devices on the mast with the antenna and CPE, and I may add a preamp. The TV antenna will be aimed approximately 48 degrees true (across the most common prevailing winds) and the CPE approximately 286 degrees (facing the prevailing winds).
I believe this should be a sufficiently stable mounting for the weight of equipment, but I am not sure if I should be concerned about potential interference between the two antennas.
I am wondering if anyone sees any concerns based on the conditions I have presented?
Thanks in advance.
2012-03-03, 02:02 PM
At least 4-ft separation measured from Yagi to nearest metal in CM4228HD
in order to NOT degrade the F/B Ratio. Gain is much more tolerant:
2012-03-03, 02:23 PM
What about optimal stacking distance for a 91XG (top) and a Winegard VHF-Hi 1713?
2012-03-04, 01:14 PM
Okay, I found the answer- 26 inches or more.
2012-03-06, 09:06 AM
Was wondering what I would need to do to combine a VHF-HI with a SBGH already in the attic that is receiving ch 13. Even though the SBGH is receiving the signal, at times the signal is low (still watchable but a few blocky patches). It is mostly fine though.
For a comparison to see if my build is good I might build a second one later and try to stack the gh4n3 with another one (to increase VHF-HI and also for fun but also to try it at another location further away).
For now, if I build a different VHF-HI antenna and join it to the UHF signals from the SBGH using a UVSJ, do I need to take care with the length of the feedline coax going from the baluns of each antenna to the UVSJ? Do they have to be the same length? Is there anything basic that I should do regarding this?
I was thinking of making a coac balun for the VHF-HI antenna to optimize it for that signal range so any thoughts on that would be great...
2012-03-06, 10:08 AM
No, you don't need to worry about cable lengths or balun polarity when combining VHF and UHF antennas. This is only necessary when combining identical antennas pointed in the same direction (and the antennas are pointed towards the transmitter) with a broadband combiner. If any of those are not true, the phase of the signal will not be the same coming out of the antennas, so there is no need to try and match phases.
2012-03-06, 04:13 PM
Thanks - hey btw would you identify combiners you have used and liked?
2012-03-06, 04:35 PM
See combiner tests at www.antennahacks.com. Since back-to-back tests, divide Loss by 2.