TV Fool  

Go Back   TV Fool > Over The Air Services > Help With Reception

Notices

Reply
 
Thread Tools
Old 26-Sep-2018, 3:12 PM   #1
BrooklinOTA
Member
 
Join Date: Dec 2013
Posts: 31
Looking for guidance around preamps

Hi Everyone,

I want to thank everyone for the amazing help I've received so far. Because of this forum, I'm getting some great college football, NFL and sports playoffs all for a bit of work and very little cash.

I have been puzzling over the situation with preamps for some time and I was hoping that someone could help me get some clarity. I understand that a preamp only helps with loss through the cable run and does nothing to benefit reception. Also, I have been discouraged from using a preamp because of the added noise that will be added.

All of that said, it appears to me that my system would benefit from the use of a preamp and here are my details:

Tv Fool report: http://www.tvfool.com/?option=com_wr...9038aaf236a07a

I have a run of 75 feet of RG6 coming from a DB8e going to a Channel Master distribution amp.

Now, when I look at calculations of loss over 75 feet of RG6 and then consider some of the channels I get that can be variable with reception, it seems the preamp would work.

Take NBC, real channel 33 for example. Channel 33 is broadcast at 587 MHZ and over a 75 foot run of RG6 I should be losing around 3.65 db.

So if that is the case, would it not make sense to introduce something like a TVPRAMP1R, that brings 2.6 db of loss into the system? Wouldn't I achieve one extra db of gain and it would help the channel be more stable when the signal is borderline in and out?

Thanks for the help!
BrooklinOTA is offline   Reply With Quote
Old 26-Sep-2018, 5:47 PM   #2
jrgagne99
Senior Member
 
Join Date: Sep 2016
Location: Canaan, NH
Posts: 152
Quote:
Originally Posted by BrooklinOTA View Post
...would it not make sense to introduce something like a TVPRAMP1R, that brings 2.6 db of loss into the system? Wouldn't I achieve one extra db of gain and it would help the channel be more stable when the signal is borderline in and out?...
Yeah, you have the general idea. I don't think any of the green stations in your report are strong enough to cause overload. Especially since you are not pointing right at 247 (right?). So I think a moderate-gain pre-amp is worth certainly worth trying.

BTW, you should probably keep this discussion all in the same thread, it makes easier if everything is in one place.
jrgagne99 is offline   Reply With Quote
Old 26-Sep-2018, 6:37 PM   #3
BrooklinOTA
Member
 
Join Date: Dec 2013
Posts: 31
Quote:
Originally Posted by jrgagne99 View Post
Yeah, you have the general idea. I don't think any of the green stations in your report are strong enough to cause overload. Especially since you are not pointing right at 247 (right?). So I think a moderate-gain pre-amp is worth certainly worth trying.

BTW, you should probably keep this discussion all in the same thread, it makes easier if everything is in one place.
Correct, I'm pointing at around 195.

Agreed, this probably should have been tagged onto my other post.
BrooklinOTA is offline   Reply With Quote
Old 26-Sep-2018, 9:40 PM   #4
ADTech
Antennas Direct Tech Supp
 
Join Date: Jan 2010
Posts: 2,846
Quote:
I understand that a preamp only helps with loss through the cable run and does nothing to benefit reception.
Actually, that's a mis-statement of how it works, it's pretty much an over-simplification.

A low-noise pre-amp's input noise figure would substitute for the combined insertion loss of the downlead and of the tuner (plus any other losses). Adding one, where appropriate, can extend the noise floor limit by a few dB, perhaps even as much as 6-10 dB for a typical tuner and preamplifier with 75' of RG6. IOW, very weak signals that would get lost in the cabling and tuner's input would have sufficient power to be above the tuner's noise floor and then may possibly be received (there are other factors..).

To do the actual calculations, you'd have to use what's usually called a "Cascaded Noise Figure" calculator or the equivalent to find the "System Noise Figure" when using (or not) a preamplifier.
__________________
Antennas Direct Tech Support

For support and recommendations regarding our products, please contact us directly at https://www.antennasdirect.com/customer-service.html

Sorry, I'm not a mod and cannot assist with your site registration.
ADTech is offline   Reply With Quote
Old 27-Sep-2018, 12:16 AM   #5
BrooklinOTA
Member
 
Join Date: Dec 2013
Posts: 31
Quote:
Originally Posted by ADTech View Post
Actually, that's a mis-statement of how it works, it's pretty much an over-simplification.

A low-noise pre-amp's input noise figure would substitute for the combined insertion loss of the downlead and of the tuner (plus any other losses). Adding one, where appropriate, can extend the noise floor limit by a few dB, perhaps even as much as 6-10 dB for a typical tuner and preamplifier with 75' of RG6. IOW, very weak signals that would get lost in the cabling and tuner's input would have sufficient power to be above the tuner's noise floor and then may possibly be received (there are other factors..).

To do the actual calculations, you'd have to use what's usually called a "Cascaded Noise Figure" calculator or the equivalent to find the "System Noise Figure" when using (or not) a preamplifier.
Thank you, this helps to make more sense of it. In your opinion do you think it is worth me trying a preamp like the RCA model?
BrooklinOTA is offline   Reply With Quote
Old 16-Oct-2018, 3:24 AM   #6
BrooklinOTA
Member
 
Join Date: Dec 2013
Posts: 31
Just an update. I installed the TVPRAMP1R this weekend and it makes a significant difference. There were no dropouts on NBC (my hardest to reach American station) and the Canadian channels in the null zone are much more stable!

Thanks for the help everyone!
BrooklinOTA is offline   Reply With Quote
Reply

Bookmarks

Go Back   TV Fool > Over The Air Services > Help With Reception


Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off




All times are GMT. The time now is 7:48 AM.


Powered by vBulletin® Version 3.8.8
Copyright ©2000 - 2018, vBulletin Solutions, Inc.
Copyright © TV Fool, LLC