91XG Attic or Roof Mount for 92397

[BikingBrian]

I might end up with a situation in which the VHF and UHF antennas are on separate masts, probably about ten feet apart. In that case, what is best for the preamp? Combine the antennas into a UVSJ before going to a single preamp? Or separate preamps with two coax lines into the house? If I go the latter route, can I use a UVSJ after the power inserters in order to avoid an A/B switch?

[GroundUrMast]

The economical approach would be, place the UVSJ on the UHF mast, leaving you with a very short run of coax from the UHF antenna to the UVSJ. Run coax from the VHF antenna to the UVSJ. Place the mast-head portion of the preamp system just below the UVSJ.

This approach favors the UHF signals which will suffer more attenuation per foot of coax than the VHF signals.

The premium solution would be to use two preamps, one for each antenna.

[BikingBrian]

Here's my blog post (with photos) about pointing my UHF antenna towards the Victorville translator. I can sum up by saying pine trees and UHF don't mix!

http://www.bikingbrian.com/2012/06/1...on-part-1-uhf/

Part 2 will be after I add the VHF antenna in the mix.

[Electron]

Tip the front of the antenna up so the antenna looks at the mountain ridge.

That way the length of the antenna is in line with signals that are bent a little as come across the ridge.

[BikingBrian]

Originally Posted by Electron

Tip the front of the antenna up so the antenna looks at the mountain ridge.

That way the length of the antenna is in line with signals that are bent a little as come across the ridge.

The translator is at 4500 feet, my cabin at 5800 feet, and the ridge in between at 5500 feet. Should I instead tilt the antenna down a bit?

[GroundUrMast]

Originally Posted by BikingBrian

The translator is at 4500 feet, my cabin at 5800 feet, and the ridge in between at 5500 feet. Should I instead tilt the antenna down a bit?

Yes, but given the distance involved when pointing north-east (26 miles) I doubt you'll see much effect unless you have a ground reflection or diffraction close in.
I think @Electron was referring to a south-westerly aim, in an attempt to receive some UHF out of Mt. Wilson. Sadly the predicted UHF conditions coincide with your neighbors local knowledge of the area.

In either case, start by bore-sighting along the boom. If aiming down on to the mesa, point straight at the transmitter antenna. If aiming toward Mt. Wilson, point the antenna at the top of the obstructing ridge. Then fine tune from that starting point, making small adjustments. Every dB of margin gleaned is well worth the effort.

[BikingBrian]

Great, thanks.

Regarding the UHF antenna aimed towards the translator, the LOS indication in TV Fool is a bit deceiving. I wouldn't consider it LOS, at least in layman's terms, because if I drew a straight line from the translator to my cabin, the hill would be in the way. The elevation profile shows the signals coming from 4500 feet, hitting the ridge at 5500 feet, then propagating straight across (no knife edge like with VHF), though I can receive them since I'm higher at 5800 feet.

The VHF antenna to be aimed toward Mt Wilson will be pointed at a ridge that's clearly visible from my roof (no photo yet).

[Tower Guy]

Originally Posted by Electron

The end result will most likely be that there will be VHF low band channels 2 thru 6 , VHF high band channels 7 thru 13 , UHF band channels 14 thru 51.

I'd opine that expanded use of channels 2-6 is extremely unlikely.

[GroundUrMast]

Yes, the trees and buildings almost always require a correcting elevation at the receiving end. Like your pine trees, the Douglas Firs here in the NW can require a 100' correction to the terrain model.

I wonder how soon we can expect the publicly accessible terrain mapping databases to include vegetation and structure detail. (When I started my career at the phone company the internet, cell phones and PC did not exist.)

[jbosh24]

Thanks for the information guys!

[Electron]

BikingBrian you are doing Most Excellent of reporting your reception situation.

Thank You.

And please provide more.

[BikingBrian]

Originally Posted by Electron

BikingBrian you are doing Most Excellent of reporting you reception situation.

Thank You.

And please provide more.

No problem. The VHF antenna will come in the mail this week, and hopefully I can make it up to the cabin this weekend to install. And I'm not done with the UHF antenna either.

[Electron]

Like I said , I do more then my best to make sure that the question askers get the correct information.
I recommended the HD7084P to cover ALL the channels for reception to the south.

Here are some Tv stations to , the south , south/east.

http://en.wikipedia.org/wiki/K39GY.

http://en.wikipedia.org/wiki/KSFV-CA.

KRVD-LP 5 , http://transition.fcc.gov/fcc-bin/tv...0&facid=128327.
http://www.ventechgroup.com

[BikingBrian]

Originally Posted by Electron

BikingBrian you are doing Most Excellent of reporting your reception situation.

Thank You.

And please provide more.

Also, in the next installment, I'll remember to give all of you credit for your help!

[Electron]

Credit for the help is nice , however I am more interested in getting the reception.

[BikingBrian]

Holy crap! I was just putzing around with the new Winegard YA-1713 VHF antenna on my back deck, and got I a lock on Channel 7!!!! (That's the TV image, not a reflection of me, sorry!)



Obviously I should do better on the roof. But I may want to tilt it up towards the nearby mountain peak. This antenna doesn't have a rotating mount like the 91XG, so any suggestions for how to get vertical tilt with the YA-1713?

[GroundUrMast]

Once you have the general aim point established, you know the forward and rear face of the mast relative to the station of interest.

Cut two pieces of sheet metal... so that each will wrap about half way around the mast. Place one on the forward face of the mast, the other on the rear. Hold them in place temporarily with tape until the antenna clamp holds them. The shim on the forward face needs to be lower than the rear so that only the bottom of the clamp contacts the shim, the front upper clamp 'teeth' need to contact the mast directly, not the shim. At the rear, the shim needs to contact only the upper 'teeth' of the antenna clamp.

If needed, add more shim stock.

An aluminum soda or beer can can supply the shim stock. Your wife's best sewing scissors can cut the aluminum. Or maybe not

[Electron]

You see you are receiving channel 7 with out even trying and the signal for KABC 7 is a weak minus -1.5 NM(dB).

This low signal strength weak reception discovery , then also spills over in to the idea of weak reception of , VHF low band channels 2 thru 6 , and UHF band channels 14 thru 51.

Yes weak signals can be received.

I did my best to get you to install a antenna that receive ALL the channels

As for aiming the antenna up a little , bend the mast a little.

[BikingBrian]

On another note, I correctly had the VHF antenna connected to the VHF portion of the UVSJ and the "line" portion of the UVSJ connected to the input of the preamp. But then stupid me connected the coax from the power inserter into the UHF portion of the UVSJ rather than the output of the preamp. Any chance I could have damaged the UVSJ or the preamp?

[GroundUrMast]

You're probably OK. The UVSJ is the least likely to have a problem with that. Some UVSJs will not pass DC or 60 Hz AC. If that's the case here, no current was flowing from the power supply to cause any damage. If the UHF port on the UVSJ presents a DC/Low-Freq-AC short, the power supply may not like being connect to a short circuit termination. Some power supplies have a non-serviceable fuse inside. Do you have a Volt-Ohm meter to check the power supply for output voltage? If not, just hook it up correctly and see if signal passes through the amplifier.