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post #11221 of 11223 Unread Today, 12:33 AM
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Quote:
Originally Posted by Larry Kenney View Post
Sorry to hear of your poor reception, Tony. Your Y10-7-13 should definitely do better than what you're getting. I receive channels 9 and 10 from the Walnut Grove transmitter site 62 miles away with an average of 17-20 dB SNR signals (don't know what that would be on the Tivo). You need 15.5 dB to produce a picture. I don't have any amplification due to the overload problem from Sutro stations, but the antenna is about 15 feet above the roof or 35 feet above the ground.

My TVFool shows the stations with these levels:
KXTV 10 8.2 NM with -82.6 power (dbM)
KVIE 9 7.1 NM with -83.8 power (dbM)

Your TVFool shows that KSBW is stronger than either of those with 17.7 NM and -73.2 power.
KNTV and KGO are in about the same range for you as KXTV and KVIE are for me:
KNTV 12 13.4 NM -77.4 power
KGO 7 7.5 NM -83.4 power
so I would suspect you to receive reliable signals from both of them.

Your signal strength for KCBA 13 is quite low, with -9.6 NM and -100.4 power. I don't have any VHF signals in that range for comparison, but I get a solid signal from KEMO 32 with a 10 element UHF yagi (an Antennas Direct S-15) and, according to TVFool it has a NM of -12.4 and 103.2 power. KQCA 46 from Walnut Grove has a NM of -7.0 and 97.8 dBM power and it comes in with a 18 to 21 db SNR signal from the CM4228, again without any amplification.

Good luck! I hope you can find where the problem is.

Larry
Thanks much Larry. Kids are in bed, wife soon... I'm working on this now.

I have KCBA! Just playing with direction every so slightly... Signal strength is not great, but a solid mid 40's to low 50's on the TiVo, which "grades" hard. Very strong SNR's on the Samsung TV of 30 show up as 65 on the TiVo, for perspective. Indeed, I found SNRs of 16 to be on the cliff...

From my viewing chair to the mast on the roof is less than one minute, so pretty slick.

I have no idea why I'm not getting KGO (ABC) and KNTV (NBC). That said, aiming south gets me NBC & ABC (KSBW 8) and now FOX (KCBA). Even I were to figure this out and get KGO and KNTV, I'd probably decide to go southward anyways. Getting KCBA is pretty big for me as KTVU FOX is one of my tougher UHF gets...

Larry, I appreciate the support.
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post #11222 of 11223 Unread Today, 07:46 AM
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Quote:
Originally Posted by TonyB1966 View Post
Thanks much Larry. Kids are in bed, wife soon... I'm working on this now.

I have KCBA! Just playing with direction every so slightly... Signal strength is not great, but a solid mid 40's to low 50's on the TiVo, which "grades" hard. Very strong SNR's on the Samsung TV of 30 show up as 65 on the TiVo, for perspective. Indeed, I found SNRs of 16 to be on the cliff...

From my viewing chair to the mast on the roof is less than one minute, so pretty slick.

I have no idea why I'm not getting KGO (ABC) and KNTV (NBC). That said, aiming south gets me NBC & ABC (KSBW 8) and now FOX (KCBA). Even I were to figure this out and get KGO and KNTV, I'd probably decide to go southward anyways. Getting KCBA is pretty big for me as KTVU FOX is one of my tougher UHF gets...

Larry, I appreciate the support.

You're having a hard time with KCBA because its antenna pattern is unfavorable for you.

http://transition.fcc.gov/fcc-bin/po...78&p360=0.111&

You're heading on the above plot is 348 degrees. If you click on KCBA on your TV Fool report it shows the terrain between you and KCBA. It also says KCBA is 19.75 KW but to you it is 0.143 KW. If you try to read the field strength at 348 degrees it's about .09. To calculate the ERP in your direction you square the field strength and multiply by the transmitter power (.09 x .09 x 19750 = 160 watts). That's not much power. In order to get more reliable reception on KCBA you need a pair of VHF antennas like I have and a preamp.

I don't know what the problem with KGO and KNTV is. TV Fool says they should be plenty strong enough. Were you able to figure out the true signal strength of these stations? It could very well be vegetation issues are causing attenuation and multipath. TV Fool doesn't take into account vegetation. Larry doesn't have any trees to look through. Attached is a spectrum analyzer image showing KVIE and part of KXTV on 9 and 10 from a friend's house. He is 62 miles from the stations but is looking through a pine forest. The signals are supposed to be flat but the trees are causing the large variation in signal strength. The signal quality will be limited to what the weakest part of the signal is, and that doesn't include multipath issues.

Chuck
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post #11223 of 11223 Unread Today, 09:43 AM
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Great stuff Chuck. I'm actually understanding more and more of what I read, I'm happy to say.

Indeed, I have vegetation here, and terrain concerns, as stated. We drive up a hill, then downward toward the lake to get to the property. Beautiful here, but I knew it was not going to be easy reception-wise. The trees though are few, literally 3 to 5, both north (Sutro direction), and a few going south to get KSBW 8 and KCBA 13. The trees are closer when aiming south, like 50 feet away, but I'm not generally going through twigs and leaves, but lower more stationary branches and trunks. KCBA is looking solid and I got the best reception around 174 degrees, as I recall (was hard reading the compass on the roof at night, not wanting to shine the flashlight around too much. I have the antenna snugged-up to the mast.

In the bedroom here, the Samsung tuner is showing 7 to 8 bars (out of 10) for KCBA. While I get higher peaks with KTVU, that FOX on UHF seems to be less predictable as it fluctuates more, in both predictable and seemingly unpredictable patterns. I've only been experimenting with VHF a few hours, but it looks to be more solid thus far.

I am using a preamp, the VHF side of the RCA dual input amp. The UHF side is terminated as I'm not using it for the DB4e. I found that I was getting better results going through the CM 7777, so I'm using it, then combining the two antennas. Would be great if one preamp gave equal or better results, and I'm curious to try again. Removing the CM 7777 preamp and Winegard combiner, making things more simplistic would be nice... That said, I've had two RCA preamps fail on me over the course of weeks, and they keep sending me new ones.

KCBA is working like a champ thus far.

Last edited by TonyB1966; Today at 09:57 AM.
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