San Francisco, CA - OTA - Page 289

Doug3214,

The only thing I can add to the excellent advice you've already been given is even if you receive all the stations from SF you'll have to expect times when some of the signals drop out. This is caused by changing temperature inversions and there's nothing you can do about it at your distance with 2 edge paths to the transmitters.

Chuck

Is there a benefit to be found with separate UHF/VHF antennas? I've also heard that at my distance a pre-amp is needed, but not too powerful. Will just any old pre-amp do? Or is that best recommended from whomever sells me the antenna?

Thanks Chuck. That is something I will have to consider, yes. Can you explain the term 'edge path'? I'm trying to soak all of this up so I can stop asking you all questions and get on with the purchase and install of the right antenna for me.

2 edge means you have at least 2 hills between you and the transmitter tower(s). LOS means Line Of Sight (no obstructions).

If you look at your TVFool report page (not the image) and click on any station's call letters, it will present you with a graph showing the transmitter location (to the left) and your house (to the right). Between the two points, you can see the location of any hill(s) impeding your reception.

With a couple of fairly strong stations on your chart, but still likely needing a preamp for the weaker channels, you will need one with a high input tolerance to overload from the stronger stations. If your installer is knowledgeable about the area, he should know of a good one to use. You might ask about a Winegard HDP269. A google search will provide details on that preamp.

I live just south of you at the corner of MarkWestSprings and Old Redwood Hy and get fairly decent reception from the UHF stations from SF. I got lucky with an attic mount in a single story house but wouldn't recommend that approach.

I have an old RS all channel antenna and a CM 7777 amp. Without the amp I get virtually nothing.

I would recommend one of the highly directional antennas and would add a rotor if you want to get, or try for stations from other directions.

KQED filed an application yesterday to increase power from 710 KW ERP to 1000 KW ERP on their existing antenna. That's an increase of 1.5 dB.

Chuck

You do have a couple of very strong local stations that may give a preamp problems. The HDP269 might be your only choice. Can you provide a few more details of what your installation will be like? Length of coax to the antenna? Any splitters in the house?

Chuck

A ballpark coax length might be 50-60 feet. I've really not looked yet. I'm not sure where I'll install on the house yet.

No splitters in the house.

Thanks, all. The results are in. The 7698p brings in as many as 57 channels, but will not get KPIX 29/5.1, KQED 30/9.1 or KTVU 44/2.1.

I believe it's the obstructions since:
1) I'm getting KICU 36/36.1 and KSTS 49/48.1, so I know I'm getting UHF.
2) I'm getting a big hole for UHF channels on Sutro.
3) Weird enough, I get both 35 (Hayward) and 7 (Sutro) for KGO. I have to believe it's angle and VHF respectively.

My question:

Is my 'mission impossible' conclusion reasonable, or is there anything else you'd try to get KPIX/KQED/KTVU?

Thanks.

KAR

I think the HDP269 should be good enough with that short coax run and no splitters without overloading. If you want to spend quite a bit more money for something a little better you can buy a Tinlee MA-82-16-77A.

http://www.tinlee.com/PDF/MA-series-info.pdf

Chuck

So you are getting some Sutro stations? KOFY, KRON, KCNS, KCSM, KBCW?

Chuck

So now it gets a little more complex. "Managing the Multipath" rays.
Inch by inch, move the antenna down, down, down, for about 2-3 feet (Each way) for a total of around 6 feet elevation changes.
then up, up, up. And mark the antenna pole with a marking pen.
You may notice signal peaks+ like every 16 inches, and signal nulls- too.
So (easier with 2 people) and a cell phone. Tune 29 and find the elevation it locks on the best.
If that doesn't work, you may need to move the antenna (Not rotate) Left, Left, or Right, Right
Allow time for buffering. (3 or so seconds) with each move.
You will notice erratic UHF reception every 3 feet moved left, right, etc. That's what blocked reception from hills do.
Try a combo amp with 2.5db of noise or less. Like the 7777

What do you consider fairly decent reception? I'm hoping to be able to use a Tivo to record shows. Do you find one time of day/year to have worse reception than others?

Thanks Chuck. I'll just need to figure out how I'm going to mount this an an antenna and I'll cooking with fire.

Chuck,

Not one.

KAR

Wow, sounds like a bit more than I intended to bite off.

I called Dick's Antennas today. Anyone know if he comes up to San Carlos?

Thanks!

KAR

Oh.... Unless you've done something wrong it's unlikely any antenna is going to work. I thought if you were missing just a few there would be hope. I wonder what the 57 channels are? There are probably at least 25 channels just from the Fremont transmitters.

Chuck

The HOA in my area can be a real pain in the rear so I chose to install a single antenna and remove the reflector to minimize the visibility. I built the antenna, leveraging the CM4220 design and increased the length of the elements to optimize the reception at the middle of the new UHF band (Channel 30). Reception for RF7 and RF12 is hit-or-miss at present but I'm planning on upgrading the antenna over the weekend. I'd like to improve the reception on RF7 in time to watch the Indy 500 on Sunday!

I went with separate antennas (CM4228 and a yagi similar to the 1713) because they offered more gain than the combination antennas. You might want to consider the separate antennas for the same reason.

You've been getting lots of good information from the guys on here. Good luck with your installation!

Larry
SF

I record KQED regularly, MasterPiece Mystery, but do not rely on any other channels for recording. If there is something I want/need to record on other channels I check the signal level that day and record if the signal is up high enough.

Seems like the weather, more than the season affects the reception for me. Right now I am getting 2,4,5 and 9 with a signal strong enough that I would record something if there was anything important this time of year, and channels 7 and 11 are too low to get more than a garbled picture or nothing at all. I get some decent higher channels but seldom watch except for 22 which always is 100% signal here. If you have a specific channel you are interested in, I'll check on it here.

I always thought that the trees Mt Tamalpais would leaf out in the summer and have an affect, but even with the wind today, it doesn't appear so.

I've got a CM4228 here not being used if you would like to try it at no expense. I had it set on a long pole and tried it in different spots along with in the attic but the old RS antenna won most of the battles.

You may not know that the FCC has largely preempted HOA rules in regards to TV antennas and small satellite dishes. Basically you can install whatever antenna is necessary for OTA with some limitations on property you own or control and tell the HOA to go pound sand.

http://www.fcc.gov/guides/over-air-r...n-devices-rule

Chuck

I consider the reception to be adequate if the station comes in 99% of the time. That means there might be 15 minutes a day without reception. Most of my stations are that good.

Signals are affected mostly by temperature inversions that can either bend the signals towards you to increase signals or away from you to decrease signals. LOS signals are mostly unaffected. Coastal fog is an indicator of temperature inversions which form most often under high pressure conditions. The height of the inversion can greatly affect what you receive. Spring seems to be the least affected season around here with summer and fall being the worst. Winter can be good or bad. Stormy conditions are a good time to check your "nominal" reception since inversions are mostly nonexistent during storms.

Chuck

I really appreciate the offer! However, I've got to clear all of this with my wife before I throw anything up on the roof. I'm doing all of the research to help prove my case here. Actually, if we're able to get Masterpiece Mystery, that will go a very long way to help my case.

Thanks for the tips on dealing with the HOA - Adding the reflector did reduce the drop-out on the converter box
but with the wind blowing the trees only Ch 22 and Ch 65 meet your criteria
for adequate reception. The guys in the DIY antenna forum like the
CM4221 clones but they're beyond my skill level. I looked on Craigslist
but didn't find any Channelmaster antennas.

I took down our dish today. I did find that the dish cabling is connected to a multiplexer in our attic, allowing connection to two different tv's in the house. Is this a problem? If so, it's not a big deal to remove the multiplexer from the equation. My existing cable is nice RG6. No big deal to run replacement run if needed.

A multiplexer is a device that directs the voltage and/or converter box signal tones to the correct satellite. 119 west, 110 west, etc.
Example: Living room is sending a request for a channel in 1-100 range
Bedroom is sending a request for a channel in the 101-200 range
A multiplexer allows independent channel viewing in 2 locations at once.
Otherwise, both rooms would be stuck on the same channel.

This switching device is not used with OTA antenna tv and should be removed.
Ben

Thanks. I'm learning a lot here. I'll head up to the attic tomorrow and pull it.

Strong signals from the north bay today. 9pm today.
First ever capture of KEMO. My portable tv showed KFTY, so they must have never changed it.
KEMO is -15db noise margin on my tvfool report. ....75 miles, 2 edge
It just so happens that I was doing some testing at this time and noticed KRCB swinging upwards of 85% signal. KFTY would reach 35%
Equipment used:
5 foot UHF Yagi, 7777 Pre-amp, 25 feet cable, battery tv
Captured in the middle of the yard. 5 foot antenna elevation.
A few months ago, on the roof. This station was not there.
Did they up the power ? Weird

There's a big high pressure building in the next few days so I'd expect all sorts of unusual reception, both good and bad.

Chuck

I don't think they've upped their power. KEMO (with PSIP still indicating KFTY) has been consistently solid in here with a normal signal of 25 to 26 dB SNR from the CM4228. During times when conditions have been improved I've seen their signal as high as 31 dB. KEMO is always stronger than KRCB here. (Wasn't watching OTA tonight, so missed the strong signals and can't say what they were doing earlier here.) I have a nice clear shot across the bay and up through the Napa Valley to Mt. St. Helena, a distance of 65 miles.

To get the signal as well as you did at the 5 foot elevation in Hayward, conditions must have been really good tonight. Since Chuck expects unusual reception in the next few days, I'll have to do an occasional check to see what's happening. Right now at 1 am, signals are all at about normal levels.

Larry
SF