Signal Amplifiers (Amps, Preamps, Distro Amps) - Page 290 - Canadian TV, Computing and Home Theatre Forums

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post #4336 of 4354 (permalink) Unread 2018-11-26, 08:12 PM
 
Join Date: Apr 2002
Location: Victoria
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Quote:
Originally Posted by ProjectSHO89 View Post
Those results are definitely not where Google says your postal code is at. They're from 3 miles north and behind Mt Douglas.

Use the interactive maps tool and pinpoint your address to generate a new report and see if it's different. Geocoding of street addresses sometimes yields unpredictable results.
You're right, I don't know where I got that link in 4332. My original link at the top of the page in post 4321 gives the same report I get by searching a new report with my postal code. Sorry, not very tech savvy over here.
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post #4337 of 4354 (permalink) Unread 2018-11-26, 08:22 PM
 
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Originally Posted by majortom View Post
It can, if used in the wrong application.
How close to the repeater transmitters are you? Possible that when you installed the preamp, it became overloaded by strong local repeaters, causing distortion.
eg what you saw as degraded signal "quality".

Are you using your antenna with the Bays in the same direction? Or are you having them in different directions? eg one towards Vancouver, one towards US/Seattle transmitters?

Whatever, if ur having trouble with whatever ur doing, try the other way.
If your intent on using an amplifier, you may need to isolate your antenna from the local repeaters as much as possible.
I'm very close to the repeaters...I can see them out the window, and they are almost directly to the south of my north facing antenna. I would guess 2 km. My antenna is aimed directly at the Vancouver transmitters. I tried half to Vancouver and half to Seattle, but the results were not great. Aimed at Vancouver, I get pretty good results which I can live with. I was just playing around with the signal amp to experiment, really. I have a 25 foot coax from my antenna to a grounding block, and then 6 feet into my DVR+. No splitters and a short run, so I don't think an amp is likely of any value. I've just ordered a Tivo, and will be interested to see how it compares with my DVR+.
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post #4338 of 4354 (permalink) Unread 2018-11-26, 10:19 PM
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A better (higher gain) antenna or more antenna height is almost always preferable to a preamp. Another solution is to have two or more antennas facing in different directions with each feeding it's own tuner. That could be separate tuners in a PVR or two or more PVRs.
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post #4339 of 4354 (permalink) Unread 2019-07-10, 09:13 PM
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Where to buy a CM7778

My 5 year old CM7778 just died and I can't find a replacement CM preamp anywhere without paying 5 times what I did for this one.

Any suggestions?
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post #4340 of 4354 (permalink) Unread 2019-07-11, 09:50 AM
 
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April Fain, I'm in the same boat.

Online, the Channel Master store is out of stock on their new pro model. So I've requested an email notification whenever they get stock.

On the upside, the new CM 7778 has had great reviews.

Delhi SFA 1483, Antennacraft Suburban VHF, CM7778
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post #4341 of 4354 (permalink) Unread 2019-07-11, 02:40 PM
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Several weeks ago I requested an email when available, got a polite note from Channel Master but no indication of when they would be available.

Is there another preamp that is recommended?
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post #4342 of 4354 (permalink) Unread 2019-07-11, 03:29 PM
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It looks like all CM preamps are out of stock. The Amplify+/CM7778HD looks like it might be a good option for the CM7778 but it's out of stock as well.
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post #4343 of 4354 (permalink) Unread 2019-07-11, 06:16 PM
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Just keep in mind the original CM 7778 had separate VHF and UHF inputs. The new CM 7778 HD has one integrated input.
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post #4344 of 4354 (permalink) Unread 2019-07-11, 06:43 PM
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A HIGH Gain Preamp is only needed if you have a LOT of Loss in Multi-Port RF Splitter(s) and Long Cables....I prepared a Spread Sheet Calculator:
https://www.digitalhome.ca/forum/81-...ml#post1321089

PS: Add Antenna to Preamp Loss (e.g. Balun Loss) to Y-axis value to determine "Total System Noise Figure".

Old CM7778 and "similar" old CM7777 claimed 2.2 and 2.0 dB Noise Figure respectively, as summarized in fol. Preamp Spec Comparison Table:
https://photos.imageevent.com/holl_a...20RevB.doc.pdf

But Calaveras measurements on old CM7777 only indicated NF between 2.8 and 3.4 dB (worse on higher Freqs)....so CM7778 was likely closer to NF~3.0 dB....when it was NEW.

Below is more recent Summary of ACTUAL measurements posted by Calaveras:
IF the utmost in Sensitivity is of primary importance, then either of the [pricey] Kitztech Preamps would be a good choice....but NOT if Overload from Strong Input Signals is likely.
IF the utmost in Overload Resistance is of primary importance, then Antenna-Direct [pricey] Juice Preamp would be a good choice.
IF lowest cost is of primary importance, then CM-3410 Distribution amp would be a good choice......it is weather resistant and has high Overload Resistance.

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Antenna Simulations, Overload Calculations, etc: http://imageevent.com/holl_ands
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post #4345 of 4354 (permalink) Unread 2019-07-11, 07:21 PM
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Quote:
Originally Posted by alebowgm View Post
Just keep in mind the original CM 7778 had separate VHF and UHF inputs.
True
Quote:
The new CM 7778 HD has one integrated input.
Not true
The new 7778 has one integrated input.
The new Amplify+/7778HD has separate UHF and VHF inputs.
https://www.channelmaster.com/Amplif.../cm-7778hd.htm



It would have been a lot easier if Channel Master had used new model numbers for new models.
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If you can not measure it, you can not improve it.
Lord Kelvin, 1883

Last edited by rabbit73; 2019-07-11 at 07:39 PM.
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post #4346 of 4354 (permalink) Unread 2019-07-11, 07:36 PM
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Quote:
Originally Posted by April Fain View Post
My 5 year old CM7778 just died and I can't find a replacement CM preamp anywhere without paying 5 times what I did for this one.

Any suggestions?
Save and Replay?
Channel Master 7778 Titan 2 CM-7778 preamp, Mast mounted Amplifer for over the air, OTA HDTV Antennas, low noise digital off air OTA amplifer for ATSC signals

https://angelelectronics.ca/shop/ota...master-cm-7778

https://www.hometechexperts.ca/produ...n-preamplifier

If you can not measure it, you can not improve it.
Lord Kelvin, 1883

Last edited by rabbit73; 2019-07-11 at 07:52 PM.
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post #4347 of 4354 (permalink) Unread 2019-07-14, 04:28 PM
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Thanks for your response.

This is interesting. I live in the US and generally buy online from Amazon.com or SolidSignal.com or even Channelmaster.com. I have been trying these and other online sites in the US and they are all out of stock and have been for several months. I am not sure why they are available in Canada or why they are not in the US.

https://www.channelmaster.com/Amplif.../cm-7778hd.htm

https://www.solidsignal.com/pview.asp?p=CM-7778

https://www.amazon.com/gp/product/B0...43sdfd-20&th=1

Thanks for the info.
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post #4348 of 4354 (permalink) Unread 2019-07-15, 11:05 AM
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Quote:
Originally Posted by April Fain View Post
This is interesting. I live in the US and generally buy online from Amazon.com or SolidSignal.com or even Channelmaster.com.
Oops; sorry about that. Since this is a Canadian forum, I assumed you lived in Canada.
Quote:
Originally Posted by April Fain View Post
Several weeks ago I requested an email when available, got a polite note from Channel Master but no indication of when they would be available.

Is there another preamp that is recommended?
We don't know enough about your situation to make an accurate suggestion about another.

Walmart has it listed, but it isn't sold by them. It's sold by F.H. OUTLET with a 79% rating. I wouldn't risk it.
https://www.walmart.com/ip/Channel-M...ifier/39669405

https://www.walmart.com/reviews/sell...8E64B5E2057419

Newark has it backordered, available end of July:
https://www.newark.com/channel-maste...C-GUSA-SKU-MDC
enter part number in search box or use Google; direct link doesn't take you all the way there for some reason that I don't understand

The Antennas Direct Juice might work, but it doesn't have an FM trap.
https://store.antennasdirect.com/JUICE.html

If you can not measure it, you can not improve it.
Lord Kelvin, 1883

Last edited by rabbit73; 2019-07-15 at 12:07 PM.
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post #4349 of 4354 (permalink) Unread 2019-07-15, 02:21 PM
 
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Well I just visited Angel Electronics and Save and Replay outlets. About 15 min drive from my home here in Mississauga. They all have antennas, cables, splitters, power inserters, connectors, etc. However, they do NOT have important things like FM Traps and UVSJs.
Their sources have dryed up according to them. They cannot get those parts. Suggestion was to try Amazon or Ebay.

There was a time when those parts were locally available. A lot of those shops have disappeared as have FTA suppliers.
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OTA, CM4221HD, 3410 amp, 4 way split, HW-150 PVR.
FTA, Openbox S9, 33” dish, PLL LNBF. Stab 90HH.
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post #4350 of 4354 (permalink) Unread 2019-07-19, 01:06 PM
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Thanks for the reply and suggestions. I may be in the US but I have been following this forum for 5+ years. I built one of the McClapp antennas 5 years ago and am still using it. I appreciate all the help this forum has been. I may give the Juice a try.
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amplifier , dtv , ota , preamp , signal strength

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