Sunday, June 11, 2006

Channel Master 7775 versus Radio Shack In-line Amplifier

In my, seemingly, never ending quest for reliable reception of the Boston Fox affiliate, I decided to upgrade my rooftop antenna's (Winegard 9032) pre-amp. I had been using a Radio Shack In-line Amplifier. As people on AVS Forum like Channel Master pre-amps, all my local stations are UHF, and my antenna is UHF only, I purchased a Channel Master 7775 UHF only pre-amp from Solid Signal. The Channel Master pre-amp costs $19 more than the Radio Shack model (plus shipping differences).

My hope was that by substituting a higher quality UHF only pre-amp, I would get somewhat less noise, somewhat more signal and have fewer hours when Fox pixelates.

By the way, this is not a definitive comparison. Atmospheric conditions might have changed significantly between the time I checked signals with the Radio Shack and when I finished installing the 7775. I did mow the lawn in the interim. However, I hope this report will help anyone wondering if the higher priced pre-amp is worth the money.

I receive 9 digital over the air channels. The following are of the form Network channel# (True channel#) Strength

PBS 2 (19) Strong
CBS 4 (30) Strong
ABC 5 (20) Strong
NBC 7 (42) Mediocre
FOX 25 (31) Intermittent
UPN 38 (39) Mediocre
PBS 44 (43) Mediocre
WB 56 (41) Intermittent
TFA 66 (23) Mediocre

According to these are all UHF stations (higher than channel 13), as 2, 4, 5, 7, are actually broadcasting on UHF channels 19, 30, 29, and 42. I'm about 31 miles away from the antenna farm and all of these transmitters are in the same general direction. I have a three way splitter which sends half the signal to my TV Room and a quarter each to my bedroom and my basement office.

Late this morning, I wrote down the "signal strength" for each of these channels from the Dish Network 411 receiver in my TV room, I then disconnected the Radio Shack in-line amplifier and recorded the signal strength without any pre-amp. And finally, I installed the Channel Master 7775 and recorded the results. I do not know what the receiver means by signal strength; I do know if it drops below 58 it will pixelate, stutter, show a signal loss dialog, and sometimes even crash the receiver making me unplug and restart it. BTW, the Dish Network 411 is an unreliable piece of junk.

The following is of the form Network Channel#: Signal with no pre-amp, Signal with RS in-line, Signal with CM 7775. NS means no signal.
PBS 2: 74, 83, 84
CBS 4: 74, 87, 88
ABC 5: 74, 86, 79
NBC 7: NS, 74, 76
FOX 25: NS, 58, 65
UPN 38: NS, 69, 74
PBS 44: NS, 62, 73
WB 56: NS, 59, 66
TFA 66: NS, 73, 79

From this data, we can see a few things. Without a pre-amp, I would only get 3 stations. The 7775 is not appreciably better than the Radio Shack for the strong UHF stations, and is even a good deal worse on ABC 5 (actually 20). But these channels are more than strong enough either way. More importantly, it is noticeably better at boosting the signal of the marginal and intermittent stations with which I've been having trouble. In particular, it boosted FOX and WB above the magic 58 level. I've been watching the signal on Fox and it oscillates within a range of 60-68 over an hour. I suppose that with the Radio Shack, the range was something like 56-64, resulting in frequent picture loss. At least the current operating range is all good enough, although a little close for comfort. My stronger channels oscillate by a point or two at most.

I've also started getting the Manchester N.H. ABC affiliate with reasonable strength ~65 despite my directional antenna being pointed in the opposite direction. Of course, other than local news, which I do not watch, there is little difference between the programming on ABC Boston versus ABC New Hampshire.

These numbers drift over the course of the year as tree leaves grow to block my angle, and then fall. Hopefully, summer has the worst conditions and this upgrade will be good enough to keep me in tacky reality programming till the leaves fall in autumn.