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ckwsp101_tv 16-Feb-2015 11:12 PM

antenna advice for Marin County

I'm on the floor of a valley with trees on ridge and nearby . The home owners association cable
system may be decommisioned in the coming months.

My tvfool report is

I'm interested in ABC,NBC,CBS,PBS,CW, FOX.
I'm experimenting with a flat roof mount 1980's Radio Shack 10 foot 10 elment yagi.
I don't have
the model as all labels gone, some rivets attaching elements rusting.
I guess 3 elements are UHF and 7 elements are VHF. The antenna is
pointed at 147 degrees magnetic using landmarks. I'm aiming just right of a 150 foot
redwood tree obstructing my line to Sutro tower. The antenna is tilted at the hill crest.
Using new 50 foot RG6 and new balum my Samsung TV scans 45 channels. After installing a
RCA preamp the Samsung scans 64 channels. Samsung reported signal strength varies.
( My model tv does not have signal quaility page)

7 ABC 2-8 bars
12 NBC 0-2 bars
29 CBS 5-10 bars
30 PBS 3-10 bars
41 ION 0-10 bars
44 FOX 0-10 bars
45 CW 0-10 bars

During bad weather I lose many channels due to wind and tree interference.
For improved reception I'm considering

Antennas Direct 91XG
Antennacraft Y10713
use RCA TVPRAMP1R preamp uhf/vhf inputs
100 ft RG6 run
non penetrating flat roof mount.

The nearby trees are on public property. I expect
my tree issues may increase going forward.

I'm using a saw horse to support the Radio Shack antenna. I plan to try other locations
on the roof.

I really want to avoid Comcast.

timgr 17-Feb-2015 6:27 PM

Trees are a problem. Look here at "Trees and UHF."

I don't think there's much you can do if the trees stay in the way. Unlikely you'll be able to go higher than a redwood tree. Redwoods are kinda narrow and tall - any chance you can move around on your roof to skirt the blockage of the big tree?

ckwsp101_tv 17-Feb-2015 7:03 PM


Thank you for responding to my inquiry. Yes the problem redwood is tall and narrow. Too tall
to go over.
After I read the tree article, I'm going to moderate my expectations.

I'm going to search for better locations on the roof with my existing RS antenna.
If I find a better location, I guess the 91XG + Y10713 still the right tools for a poor location.

ckwsp101_tv 2-Mar-2015 6:46 PM

1 Attachment(s)
Here is an update

I deployed the Antennas Direct 91XG + AntennaCraft Y10713 at temporary locations
on the roof. Boresight 91XG at hill ridge towards Sutro Tower.

Reception improved compared to the old RS yagi.
There are fewer intermittant dropouts. I can receive all of my must have channels when
conditions are good. KTVU (RF 44) remains a challenge. Most of the remaining dropsouts
on KTVU.

To make more progress, I need a better way to measure signal quality.
Accessing the Samsung TV Signal Strength screen is awkward.

I appreciate the wealth of information offered in this forum.

ckwsp101_tv 15-Mar-2015 9:27 PM

I am now using a SiliconDust HDTC-2US as a diagnostic tool.

91XG + 50ft RG6 + HDTC-2US

RF Strength Strength Signal Quality
29 80 90
43 73 78
44 75 67-78
45 81 85

91XG + RCA TVPRAMP1R + 100ft RG6 + HDTC-2US

29 100 98
43 100 85
44 100 73-81
45 100 90

I still experience intermittent reception
on KTVU (RF44). The stations on RF43, RF44 and RF45 come from Sutro Tower.
Could multipath interference still be an issue dispite deploying
the Antennas Direct 91XG? The RF44 flutuating signal quality looks suspious.
Signal quality on R29,RF43 and RF45 are stable.

Aiming between trees to hill crest limits my roof antenna placement.
Once I get a better mast, I will resume adjusting high. Right now using the
saw horse and pvc pole.

If it is multipath interference, I read stacking a 2nd 91XG may help.
I don't expect perfect reception. Just fewer intermittent events.

I agree using a chainsaw on the near trees would help :)

Tim 15-Mar-2015 11:48 PM

Have you tried tilting the front of the antenna up a bit? It sometimes helps, especially with 2 edge signals...

ckwsp101_tv 16-Mar-2015 12:26 AM


Yes I'm using the tilt feature on the 91XG.

Flint Ridge 16-Mar-2015 1:04 AM

What is your proposed height with a new mast etc? That extra height might be worth it. As the 91XG and the VHF under it are really small antennas overall, I would be pushing the height for testing.

ckwsp101_tv 16-Mar-2015 2:08 AM

Flint Ridge,

I planning a 10 or 15 foot mast on the non penetrating roof mount. That will put the
antennas 25 AGL. I am going
to start low and see how that goes. This will be my first roof antenna :)
I'm not going to get above the redwood tree which is just left of my sight line to Sutro Tower.

My desired stations are still 2edge signals at 50 feet.
tvfool 50 ft prediction:

I will miss the home owners community cable system. That system's head end
was on the ridge with LOS to all of the desired stations.

Flint Ridge 16-Mar-2015 3:00 AM

If you could mange that 50' height it would be a 1.2 db gain in theory. As db's double in strength every 3 db's, than that would (in theory) be 33% stronger signal. Pesky db's are funny little things we chase after, but that could be worth the additional effort/height.

Most of my channels are 2Edge and weaker than your Fox station, so maybe you can get the reliability up, not perfect, but better. Stacking properly 91XG's might get you 2+ db's as well. That is a really nice antenna.

ckwsp101_tv 16-Mar-2015 3:58 AM

My short term objective is improved signal quality. Signal gain will be a secondary goal.
I'm still experimenting with the HDTC-2US.

GroundUrMast 16-Mar-2015 3:19 PM


Originally Posted by ckwsp101_tv (Post 50128)
My short term objective is improved signal quality. Signal gain will be a secondary goal.
I'm still experimenting with the HDTC-2US.

That would be my goal as well. Signal Quality is the single most important parameter reported by the HDHR metering. As you've observed, stable signal quality greater than '60' is a great predictor of reliable reception.

Multipath or active interference are at the the top of my list of theories... To prove or disprove a theory,I'd be experimenting with antenna location, height & aim. Also, don't rule out searching for equipment or devises in or near your home that may be producing interference.

ckwsp101_tv 17-Mar-2015 3:09 AM

GroundUrMast ,

Glad to know I'm going in the right direction.

It appears my sight line to Sutro Tower goes right through a Extenet Micro Cell tower along a public road. I have email to Extenet about my TV reception concerns.
The HDTC-2US reports unlabeled "auto" Signal Strength
of 70% on RF 58 , RF59, RF 60 and RF 61.

When I point the 91XG 15 degrees off line of Sutro
RF 44 Signal Quality improves.
But RF 29, RF 43 and RF 45 Signal Quality goes down :(

(left of redwood tree to ridge)
91XG + RCA TVPRAMP1R + 100ft RG6 + HRTC-2US

29 100 69-71
43 100 85
44 100 90
45 100 81

RF 44 channel specific interference? Even when coming from same tower it can happen :confused:

My best roof location can point left or right of the big redwood tree.
When I get a better mast I will try adjusting the antenna height. Will 6 inch increments
be a good starting place ? Maybe I will go back to pointing right of the redwood tree with height adjustment. I read the articles on stacking identical antennas to manage multipath
interference. That will be a last resort.

Once the above resolved, I need to deal with NBC RF 12 which is Signal Strength 87 and Signal Quality 60.
The Y10713 is really compact compared to my old 10 foot Radio Shack antenna.

GroundUrMast 17-Mar-2015 4:11 AM


RF 44 channel specific interference? Even when coming from same tower it can happen
Yes, interference can be, and often is, specific to a single channel. Spurious RF may be relatively stable in frequency and narrow in bandwidth, in which case it will only affect a TV channel if the interfering signal lands in the frequency range of that TV signal. Interference sources can be cell phones, or the towers that serve them, FM transmitters, computers or appliances in your home, energy saving light bulbs, etc. Tracking them down, especially if they are outside your home, can be difficult.

If you are seeing 'signal strength' reported by your HDHR tuner as "100", you may be approaching a signal level that could cause tuner overload. As long as the signal quality has not dropped or become unstable compared to the reported signal quality with no amplification, you don't have to be concerned. But there's certainly no need for anymore amplification when the HDHR signal strength is '90' or higher.

ckwsp101_tv 19-Mar-2015 10:00 PM

The UHF reception good enough for time being. I like the Antennas Direct 91XG.

Now I have VHF reception issues :confused:

I'm using an AntennaCraft Y10713 on a separate saw horse to receive KNTV (NBC) RF 12. During a sunset bad reception event Symbol Quailty drops to zero. Signal Quality 46.
Signal Strength 78.

`pwd`/hdhomerun_config 10519452 get /tuner1/debug

tun: ch=auto:12 lock=8vsb:207000000 ss=78 snq=46 seq=0 dbg=-5700/-8984
dev: bps=19885888 resync=0 overflow=0
ts: bps=19885888 te=1976751 miss=87041 crc=0
net: pps=0 err=0 stop=0

During the above event RF 7 comes in fine. I'm guessing RF 12 interference.

Here is RF 12 good daytime readings from SiliconDust HDTC-2US. The Y10713 aimed
towards San Bruno. During good reception Y10713 has good directivity. Best signal
strength pointing towards San Bruno Mountain (transmitter location).

Virtual Channel none
Frequency 207.000 MHz
Program Number 3
Modulation Lock 8vsb
Signal Strength 80%
Signal Quality 54%
Symbol Quality 100%

During the RF 12 bad reception event changing aim of Y10713 did not improve Signal/Symbol Quailty.

I will need a longer cable to try different roof locations for the Y10713.

I have a second Y10713 on order from Solid Signal :D
That way I have option to experiment with stacking to address possible multipath interference. I don't need additional gain.

GroundUrMast 19-Mar-2015 10:07 PM

Sounds like a plan. With added cable length you can experiment with combinations of height and location.

"Sunset ... event" reminds me of my telcom career. Our crew maintained a point to point microwave link that had problems during the time of the year when the setting sun would pass through the beam of the west facing antenna. There was simply no way to block the RF from the sun and we couldn't find a way to move the mountain that the antenna was located on. :(

ckwsp101_tv 29-May-2015 7:11 PM

An update

The homeowner association turning off the community basic cable service June 30th :<.

Currently using 2 Y10713 in vertical stacked phased array pointing to mount san bruno. Using 29 inch
spacing between the antennas.

On my SiliconDust HDTC-2US Signal Strength increased 2%. Signal Quality increased 6%?
During high wind event RF12 Signal Quality fluctuations went down.
With a single Y10713 on windy day Signal Quality fluctuation spread was 6% or greater.
The vertical stacked 2 Y10713 configuration tightened (reduced) Signal Quality fluctuation to 2%.
On rare occasions Symbol Quality is still lost with the stacked Y10713 configuration.
Still much improved over a single Y10713.

During the same high wind event RF44 Signal Quality fluctuation spread 8% or greater.
The Symbol Quality held up. So the picture looks ok. The 91XG also experiencing multipath interference.

Right now I'm the only house with an OTA array.

Tim 30-May-2015 12:19 AM

Thanks for the is always nice to hear how things are working out.

ckwsp101_tv 4-Oct-2017 1:31 AM

An update

I'm the only residence with multiple big antennas.
I had to educate the home owners association about my right to deploy an antenna array. ;)

UHF channels still viewable.
Using latest SiliconDust firmware. The firmware update changed signal quality scale.

11.1 (RF 12) is still the challenging channel. Frequent reception failures compared
to 12 months ago. Stacked VHF antenna balun lead wires are breaking down.
Unplugging one VHF antenna drops signal quality by 10%.
I think stacking the VHF antennas is still a win.

RF 12 drops off reception cliff when signal quality drops below 50%

Conditions have changed for the worst of the last year.

Tuner Channel SS SNQ
0 7 ss=96 snq=90
1 7 ss=96 snq=90
0 12 ss=75 snq=58
1 12 ss=76 snq=59
0 49 ss=78 snq=80
1 49 ss=78 snq=81

My plan is to replace the VHF baluns.
I read in another posting that quality external baluns are hard to source :(

Trim some near branches.

If that does not improve situation, I may look for a new location for the VHF
antenna stack. Keep the UHF antenna at current location on roof.

I'm lucky to receive alternate KNTVHD 11.3 (RF 49).

rabbit73 5-Oct-2017 1:04 AM

Welcome back, ckwsp101_tv

I can't comment on your signals because I don't know your location and your tvfool signal report is no longer on the server.

I do, however, have a few comments on the balun replacement.

My favorite outdoor balun was the original Channel Master 94444 balun, which is now hard to find. I tried to order some on eBay, but the sellers kept sending me the new 94444 with the ring terminals, even though their photo showed the original balun.

It's really confusing when Channel Master changes the design but doesn't change the model number. They have done the same thing with the CM7777 preamp, which is now in its 3rd generation.

I finally found a few original baluns and was able to make a comparison between the old and the new 94444. This thread shows my test results:

The other point, which you might already know, is that the two baluns must be in phase. If they are out of phase, the main lobe will split in two with a null between at the aim point. You have to reverse the leads on just one of the baluns to see which is the way that will produce one lobe and an increase in gain.

That's what happens with horizontal stacking; I've never tried it with vertical stacking.

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