- Unusual Reverb problem - 1 Update
- Antennae Booster - 3 Updates
- VCR plays color tapes in B&W only? - 1 Update
| "jurb...@gmail.com" <jurb6006@gmail.com>: Sep 28 06:21AM -0700 Weird ? I had one that howled from feedback anytime the reverb was on. The solution ? I reversed the speaker wires. |
| "Ron D." <ron.dozier@gmail.com>: Sep 27 11:46AM -0700 Measurements: The CM-7777 has only one input. I used an OTA signal, not on the same day. I measured before the pre-amp one day and after the power injector (about 30') on another day. Cable is copper clad RG6QS. Measured with a Sencore SLM1453i http://salestores.com/sencor01.html. These measurements were done before the re-assignment of channels. The measurement is problematic because of 1) Tilt and 2) different days. "Evaluation of a Winegard HD8200U Antenna with a Channel Master CM-7777 30 dB mast mounted Preamp" FM trap is enabled in the antenna pre-amp. May 2019 Voltages in Columns C and F are in dBuV Gain is just Column F minus Column C @antenna (N3) @In Attic (N4) Gain(N5) 2 53.6 73.5 19.9 3 42.4 58.0 15.6 4 47.5 67.5 20.0 5 29.9 54.1 24.2 6 59.5 80.6 21.1 7 Fail 37.4 Fail 8 16.1 Fail 41.6 Fail 9 22 Fail 38.1 Fail 10 * * 46.5 Fail 11 * 39.4 Fail 12 36.7 58.4 21.7 13 * * 35.0 Fail 14 * * 28.5 Fail 15 * * 29.2 Fail 16 * * 31.6 Fail 17 * * N5 49.2 18 * * 27.7 Fail 19 * * 39.5 Fail 20 * * 28.9 Fail 21 27.6 Fail 27.6 22 43.4 63.6 20.2 23 * * 25.9 Fail 24 * * 28.4 Fail 25 * * 34.3 Fail 26 32.2 55.2 23.0 27 * * 29.2 Fail 28 * * 27.6 Fail 29 * * 25.8 Fail 30 * * 26.8 Fail 31 21.2 48.7 27.5 32 32.3 56.7 24.4 33 * * 30.1 Fail 34 34.4 * 56.0 21.6 35 * * 27.4 36 * * 30.2 37 * * 30.7 38 * * 39.0 39 * * 28.7 40 * * 33.1 41 * * N1 31.2 42 U U N6 55.5 43 * * 31.3 44 U U N7 Missed a few here, "I think the reason for the * @antenna is that the Sencore didn't find anything Using 8VSB modulation. Not sure." TVFool data from Highest to lowest NF 6 (6.1) ABC NM: 42.6db Pwr -48.2dbm 2Edge, 28.8 miles ... 42 (29.1) Fox NM: 21.5 Pwr: -69.4 2Edge, 28.9 miles On one TV using a converter box, it shows 29/100 for signal strength on it's internal meter for 29.1 and 91 for channel 6.1. This includes another amp at 35 feet (unknown gain) from the 7777, then 65 feet to a 2-way splitter and about 35' to the TV. The "stupid" Samsung "Smart TV" only shows s/n ratio. I do have a "tuner" that will show both in real units. The system is/will be: Mast amp (currently CM-7777, plan to change to a Kitz lower NF amplifier) 30'; RG-6QS copper clad Power injector in attic Variable 0-18db gain amplifier using an attenuator 65'; RG-6QS copper clad to basement; About 40' to each TV location (some less, some more) Currently: A 2-way splitter to two TV's about 40' away. Planned: Blonder Tongue BIDA 75-43a (30-45 db Gain with tilt compensation cards and variable) that replaces a Tin Lee amplifier four 24 db 4-way taps to 12 locations (existing, but not currently used because of a broken amplifier) Locations are around 40' away. The gain is unknown because the AMP and attenuator WAS prior to the 2-way splitter and it was recently moved to the attic as is. performance is definitely better. My main distribution amp died and I'm planning to replace it with a Blonder-tongue BID 75a-43 for 12 locations fed by four 4-way 24 db taps. This has available various "tilt cards", but might consider a custom VHF attenuator. I think the CM-7777 might overload with cellular signals. Why copper clad? Friends that were in the satellite TV industry gave me 1000 feet. |
| Ralph Mowery <rmowery28146@earthlink.net>: Sep 27 04:46PM -0400 In article <5ac1d4c4-3a0b-4602-9ff1-4df219d352c6n@googlegroups.com>, ron.dozier@gmail.com says... > My main distribution amp died and I'm planning to replace it with a Blonder-tongue BID 75a-43 for 12 locations fed by four 4-way 24 db taps. > This has available various "tilt cards", but might consider a custom VHF attenuator. I think the CM-7777 might overload with cellular signals. > Why copper clad? Friends that were in the satellite TV industry gave me 1000 feet. The day and time of day can make much difference. I monitored a ham repeater all the time that is about 40 miles away by air. It normally showed a 3 on a scale of 0 to 10. Some days there were no signal (about two or three times a month), and about the same number of times it pinned the meter on the high side. That was on 220 MHz. There is very little loss in the copper clad cable (as long as the copper is not broken or missing) at TV frequencies due to the skin effect compaired to solid copper. If there was much loss it would not be used. The iron core does make for a stiff center pin for the connection. The S/N is really more important that the signal strength. You may be boosting the noise along with the signal and the TV will not be able to decode the signal. |
| Michael Terrell <terrell.michael.a@gmail.com>: Sep 27 05:28PM -0700 On Saturday, September 26, 2020 at 11:14:26 PM UTC-4, Jeff Liebermann wrote: > Note that this is lithium based and not white-lithium grease. > Please note that very little of this has much to do with a receive > only TV antenna, rotor, and mast/tower. I haven't seen one used in decades. I think that it was an article in the late '60s that recommended it. Some really cheap TV rotors used sleeve bearings, that corroded. Pot metal against brass with crap lube didn't last very long. OTOH, the old Alliance rotors often had a crumbling rubber top seal that let water into the housings. I rebuilt a lot of those that were already 30 years old. A new seal, a new run cap and new control cable put them back into service. A direct strike would vaporize that strap, but if it was a lesser hit, it would help. I had a CATV tower hit once. The audio wiring at the site was unsheilded. The EMP from the high current pulse fried the aural inputs of every modulator. Nothing was done right when the site was built. The tower was well grounded, with three concrete pours that went 60' into the ground for the self supporting tower, but the lines from the tower entered the building without ground blocks. The equipment used the building's neutral for grounding. They had punched holes in the ceiling tiles to run cable all over the place. I had to replace the RCA CA3240 ICs in every modulator, then I rewired the site. Ground rods under the equipment racks. A 19" relay panel was used to make a grounding plate for all the Coax entering or leaving the building. Large Panduit wire duct ran from the Microwave racks to the equipment racks. The idiot manager tried to tell me that there was no way to hold the wires in it, with the bottom open. A case of pencils solved that. Insert them, one per foot. Run the cables. Snap on the covers and remove the pencils if you want to. We never had another problem indoors, but we did lose some coax coming down the tower. A 1400 pound Ch4 antenna was at the top, to pick up a distant TV station. Rather than rip out all the underground cable to replace it, it left the tower about 50 feet up, and sloped to the roof of the building to allow plenty of room for big trucks to pass underneath. As a Broadcast engineer, I've seen more than one tower take a direct strike. It plays hell with the power lines for the tower lights. The stations are too cheap to use a transformer for isolation at the tower base, so the wires have to be repaired quite often. The tallest tower I've worked at was 1700' with two TV stations, five FM stations a Motorola Trunking system and a bunch of government radios on it in North Central Florida. |
| crazy chicken <craziestchicken2007@gmail.com>: Sep 27 05:27PM -0700 Thank you so much! I will tell you if any of this works! If it does, anyone else that comes into the google group will see your message and leave! |
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