Pre-amp comparison?

n3ntj

I currently use the Radio Shack pre-amp model# 15-2507 which is rated "up to 30 db" (UHF/VHF) at an unknown db noise rating. It works quite well; been using it for 4+ years. One RG-6 feed in and out (meanly no separate UHF/VHF inputs). Costs approx. $60

I am near Harrisburg, PA and trying to get the Phily stations (approx. 75-85 miles away). I can currently get them all except 6. Channels 12 and 57 are iffy and come and go. I am using an 8 bay Channel Master UHF antenna (4228 rated at 15.8 db gain) pointed to the Phily antenna farm. This antenna supposedly should do ok on hi-VHF. I will be making a simple 85 MHz dipole for ch 6 this week. I am considering a dual input pre-amp (one for UHF and one for VHF). I could get ch. 6-1 (digital ch. 64) no problem before they went back to Ch. 6.

I see these are popular-

Channel Master CM7778 rated at VHF Gain: 16 dB (VHF Noise Figure: 3.0 dB) and UHF Gain: 23 dB (UHF Noise Figure: 2.2 dB). Single UHF/VHF input. $51

Channel Master CM7777 rated at VHF Gain: 23 dB (VHF Noise Figure: 2.8 dB) and UHF Gain: 26 dB (UHF Noise Figure: 2.0 dB). Dual UHF/VHF inputs. $51

Wingard 8275 rated at VHF Gain: 29 dB (VHF Noise Figure: 2.9 dB) and UHF Gain: 28 dB (UHF Noise Figure: 2.8 dB). Single UHF/VHF input. $40

Feedback on these or others?

Or would you simply recommend a UHF/VHF combiner and simply connecting a VHF dipole to my system this way with the current amp and UHF antenna? Can you recommend a combiner?

IDRick

Welcome to the forums! Can you please post your tvfool.com results for your actual location? The CM 7777 is an excellent pre-amp but is only recommended for fringe locations and to overcome high distribution losses. Tell us more about your tv-distribution. How many tvs? Number of splitters? Total length of cable run?

Also, I presume that you will replace the RS shack pre-amp with the new pre-amp, correct? Putting two pre-amps together is a no-no.

HTH

Rick

Tower Guy

Here's your tvfool report using your qrz.com address:
http://www.tvfool.com/?option=com_wr...618ae75b9b74e1

The Antennacraft Y5-2-6 would be better than a homemade dipole.

This is the optimum combiner at an attractive price:
http://www.amazon.com/Channel-Master...5628323&sr=8-1

The cheaper HLSJ would also do the job.

The 7777 preamp is too much gain for you. Channels 8, 30, and 47 make preamp overload problematic. Watch out for overload from WMHX. You may need an FM trap

crabby_bob

This is purely anecdotal information and I can't explain it but I have both the RS 15-2507 and the CM7777. The 15-2507 is the same as the Antennacraft 10G201 which has an average gain of 30db and a noise rating of 4.0dB VHF and 3.5dB UHF. In my application the signal gain must have been more important than the noise because I got better results with the RS model. It's been up for a few years and it's still working.

I plan to put up a high VHF antenna in the next few weeks and am thinking about using a seperate preamp for it. The Wingard 8275 looks like a good choice.

n3ntj

Where is WMHX? According to the FCC database, that is not a valid TV callsign.

WGAL, WGCB, and WPMT are all to the south of my location about 8 miles, and my UHF antenna is pointed to the east. I get both of these currently around 95-100% and both come in approx. 90° to the antenna's side. At 30 db, I don't get overload currently. An FM trap may hurt since the VHF station I am trying to receive is channel 6.

The Antennacraft Y5-2-6 won't fit in my attic b/w the trusses; which is why I plan on on making a simple dipole.

Is the channel 6 Jointenna a combiner that works w/ a ch. 6 tuned antenna and another antenna not tuned to channel 6; the Jointenna essentially prevents the 2nd antenna from tuning ch. 6 so that the other antenna (tuned to ch. 6) can do it's thing? Essentially an input highly notched @ 85 MHz (+/- 3 MHz) and another input w/ a 85 MHz bandpass filter with a 6 MHz bandwidth?

I'd only use one pre-amp in the line. I have 1 TV hooked up to this antenna but 1 splitter (TV and DVR). The total length of RG-6 is about 40' b/w TV and antenna.

dewster1977

WMHX is a radio station 106.7 FM

Tower Guy

You've got the right idea. The Jointenna was designed in the analog era, so the notch frequency may be closer to the visual carrier.

Jator

Hi n3ntj,

What part of Harrisburg are you in? I'm in Camp Hill (Highland Park, right at the I-83/SR581 interchange).

I have a the Eagle Aspen DTV2BUHF and a channel master 7777. The pre-amp was necessary as I was only getting one of the local channels on a 150' cable run. I live in a 2 story home and the cable ran down to the basebement and then back up to a 2nd story bedroom.

If I sit on my roof with a short cable plugged directly into my TV tuner (USB) attached to the laptop, no problem, but even the run down to the basement kills most of the channels when I test from there. Pre-amp fixed the missing channels however. (RG6 cable used, might even be Quad shielding, I can't remember what I used, also used compression ends).

I am suprised you can get the Philly stations. Please let me know if you are succesful as I would be willing to invest in a larger antenna if I could pull in those stations as well.

Jay

n3ntj

Hi Jay:

I am actually down near Mount Joy. I just used 'Harrisburg' as a reference since its a bigger city. Yep, if you look at the transmission patterns of the Philly stations, I shouldn't really be able to get them, but with my setup, I can get most of them (except 6-1 (now VHF), and sometimes 57-1 and 12-1).

I use only RG-6 quad shield in my setup.

I may just try the Jointenna 6 to see how it works, plus its pretty cheap.

There are actually a few reasons I don't want to switch pre-amps that I didn't get into in my first post (to prevent confusion).

I have 2 antennas in my attic. A homebrew UHF/hi-band VHF one I made over 25 years ago that still works. I have made some minor adjustments using a network analyzer to tweak it. This one is pointed towards Harrisburg (approx. 20 miles away). The CM 4228 is pointed towards Philly.

I actually have 2 amps, just only 1 power source connected. Both lines (one from each antenna) are separate down to my TV in the family room. In lieu of a switch, I simply plug the 'Philly' labeled RG-6 into the power source for the pre-amp. When I want to watch a H'burg station, I swap out RG-6 and plug that one into the pre-amp's power supply. I know this is a little antiquated, but it works for me. Just never looked for a coaxial switch.

If I changed amps, I don't know if I could still use the same power supply and just change the actual amp at the antenna. If not, I would have to buy 2 pre-amps.

Matt

n3ntj

Update - I made a dipole out of 300 ohm twinlead (66' in length) and connected to via a 300-75 ohm balun and RG-6 to my amp. Still no signal on channel 6 from Phily. They even raised their output power to approx. 30KW a few days ago. Maybe I just won't be able to get them now on VHF. I am west of Lancaster (approx. 70 west of Phily).