CM-7777 / 7778: "New & Improved"?

Well, crap. They cheapened it and raised the price.

More bad news about Channel Master. Their products just are not what they used to be. Their antennas are now inferior Chinese made imitations, and now they have ruined their very good preamps as well. The 7777 and 7778 were highly regarded for their low noise figure, and as well as separate UHF/VHF inputs. They were very good for fringe reception and combining separate UHF and VHF antennas. Now, with the new versions, you have no separate inputs and a very high noise figure. Bad specifications. Another big disappointment from what was once a very good company. Ever since the PCT takeover, their OTA reception products have sadly deteriorated.

Is anyone here motivated enough to pop the cover off a couple of these and see if the amplifier circuitry has changed? `I find it unlikely that there is an amplifier transistor that costs a few cents less than the one they were using that is noisier and that they are simply saving money by using a less expensive one. It is hard to imagine that saving a few cents per unit in amplifier parts cost controlled the manufacturing decision for this $50 or more item when they apparently continue to incur the cost of using the same metal case, which costs them several times more than the amplifier transistor or IC does.

The specs for Winegard and Channel Master amps were all arrived at over a decade ago. There might not be any difference in the noise characteristics of the old and new amps. There might just be rating methodology differences.

The Winegard preamps that were designated as having 28dB gain actually gained closer to 36dB from 500 to 550 MHz. Winegard could reasonably call them 30dB gain amps if they so choose. Intermodulation at various loading levels was calculated using NTSC waveforms. Who knows what the intermodulation would be when the channels are ATSC "boxcars"?

Weren't the Channel Master published gains 23dB for the "low gain" model and 26dB for the high gain? Now having 16 dB and 30dB models looks like they offers better choices to most users.

As I have posted here many times, I did side by side bench comparisons between Winegard and Channel Master 23dB amps at a commercial antenna headend trying to rescue a weak 8VSB signal among stronger signals and the Channel Masters consistently outperformed the Wineards even though the Winegard'published specs were much better. This was back when the analogs were still on the air and I could also visually "see" the excessive channel load beating the snots out of the weakest analog signals in the Winegard amps but not the Channel Master ones. The Channel Master 77XX amps were also in better shielded cases. For the money. you can't lose with the Channel Master. The only circumstance under which I might favor a Winegard preamp is if I needed a lower gain model than Channel Master makes.

Unless Antennacraft still makes pre-amps with separate VHF & UHF ports, I might have to get another RCA TVPRAMP1R pre-amp, should the one I have now quits working. I didn't think about getting the Channelmaster CM-7777 pre-amp before I bought the RCA model. I bought a pre-amp with separate VHF & UHF ports specifically for using separate VHF UHF antennas later on (bought my current pre-amp in 2010, while I got the new antennas in November 2011, & installed a month later). I don't know how well using a regular VHF/UHF joiner would work hooked to a single port pre-amp. I never put much thought into that, as I mistakingly bought an Antennas Direct VHF/UHF combiner in 2009, when I bought the Winegard HD-1080 antenna for 1 station. Using the combiner disabled the UHF on the old VHF/UHF antenna (naive at the time).

Both Channelmaster & Winegard must think we all use VHF/UHF combo antennas, that separate VHF & UHF ports aren't needed anymore. There might not be as many VHF only antennas as there were in the past, but the UHF portion of the VHF/UHF combo antennas usually focus more VHF than UHF, & some people need bigger UHF only antennas to pull in some stations.

Thankfully, Antennacraft now has new models with separate VHF and UHF inputs, with both medium gain and high gain versions. However, the noise figure may not be quite as low as the old 7778/7777, but appears to be very close, at 2.5 UHF vs 2.0 UHF on the original CM. Also, Solid Signal still sells a Winegard version with separate inputs as well.

Channel Master may have decided that it tends to benefit from confusion. If a customer has determined that he desires a 7777 or 7778 and endeavors to purchase one, then Channel Master would like to furnish him with a preamplifier and that may be easier to do if they don't automatically have to re-educate the customer.

And I am a big fan of the original Channel Master products as well, although I am not as technically minded as some on this forum. I am a mere consumer who has used their products over the years with very satisfactory results. I am sorry that their original antenna designs are no longer available, as when they were manufactured in Smithfield, NC. I particularly endorse their original4248/4257 and 4228 UHF antennas based upon personal experience. It is a shame those versions are no longer in production, instead of the newer Chinese made imitations. They could at least "attempt" a new version of the 4248 diamond antenna like they did with the 4228, but that doesn't appear to be happening. Looks like they gave that market to the 43XG/91XG.

Looks like it may take some hunting to find one now. Solid Signal lists the 7777 with "Availability: more than two weeks", along with the following message that they received from CM:

Warren may still have them. Call first.
http://www.warrenelectronics.com/antennas/7777.htm

Or Summit Source.
http://www.summitsource.com/

Is the noise figure of these preamps determined by the indoor power supply, or the outside part of the preamp that is placed at the antenna? Just wondering, if I ever had to replace the old Channel Master power supply with the new version, would the results be different? I am assuming the power level/gain figure would also be different. I just know the low noise figure of the originall 7777 was a highly regarded feature, so just wanted to know if the power supply itself played a role. The new version has an entirely different power supply.

Noise figure is primarily determined by the "front-end" of the amplifier module itself. Passive components have an effect, but the primary determinant is usually the first semiconductor in the amplification circuit.

ota.dt.man:

Thanks for letting us know about the "new" 7777.

A short in the coax between the preamp and the power supply is common.

I wonder if the new power supply has protection from a coax short. The 0747 PS has a built-in resettable fuse(self-resetting) that protects it from a short.

Most "old" power supplies are linear supplies. Many "new" power supplies are "switching" supplies. I can't tell one internal design from the other by looking at the cases. I haven't ruined a switching power supply by shorting its output in over 20 years Admittedly, YMMV

The wall-wart for a linear PS is much heavier than a "switcher" because it contains a transformer for 60 Hz. The input AC voltage range is usually greater for the "switcher," like 100 to 240 V.

I have decided NOT to buy the new CM-7777, and I have ordered the Winegard AP-8275.

Here's why...

I called the Channel Master Tech Helpline and asked about the new 7777 vs the old 7777. The tech didn't sound too confident in the design changes. He was reluctant to be specific about the noise value of the new amp, and would only say that it was "less than 5.0", and he thought that it was "pretty good". He then told me that he had some of the old 7777 amps that he would be willing to sell me as "open-box" items for $69. I declined.

The Winegard AP-8275 has 28dB of UHF gain, and Winegard publishes the noise value as 2.8dB for UHF. In addition to that, I was able to buy the 8275 from SolidSignal for $37; almost half the price of the 7777.

I live equidistant from four broadcast markets here in Michigan: Detroit, Lansing, Flint and Windsor Canada. With my current antenna set-up (which includes the CM-0068DSB pre-amp), I am able to receive 43 channels. Of those, 31 are worth watching and 5 of those have the occasional drop-out. My springtime project is to relocate my two Winegard HD-76 series antennas to a different peak of the house, raise them an additional six feet and install the new, higher gain 8275 pre-amp. Hopefully this will solve the drop-out problem.

I just called Warren Electronics. They still have the original 7777 in stock.

The original CM7777 was arguably the best recommended consumer grade preamp, with good design circuitry and low noise factor. So it is quite aggravating that PCT would choose to eliminate the original high quality Channel Master products and replace them with inferior imitations, including antennas. It is also frustrating that the original 4228 and 4248 antennas are no longer in production. PCT has pretty much destroyed the original Channel Master company.

Will perhaps consider a Winegard preamp, although I would like to see their noise figure a bit lower like the original Channel Master. And, as far as the mclapp antennas, they appear to be very good modifications of the original Channel Master bowtie designs. However, what I really want is an original CM4248 or 4257, as those UHF diamond antennas give me better results than the 91XG. It frustrates me that PCT stopped production of those models.

Sounds like CM is definitely now nothing more than just a name of a formerly great US company, to be bought and sold and slapped onto cheap chinese-made products. Like RCA, Zenith, Polaroid, (soon to be) Kodak, etc.

I have strong, full power local channels within 10 -20 miles, from Greenville/Spartanburg/Asheville, but I also receive distant signals from Charlotte at about 75 miles. Zip code 29607. WBTV-3 on RF23 is my strongest distant signal, but RF47, 39, and 22 come in good as well. WSOC RF30 translator is a bit of a challenge because of low power, but I am able to receive it using a CM4248 antenna in the attic with a low noise preamp from Ability HDTV. I had tried a 7778 and 7777, but only the Ability amp would maintain the low power signal without dropouts. With the UHF antenna pointed towards Charlotte, I receive those distant channels, as well as my true locals including RF7 and RF13. For my other TV, I use an original 4228 into the UHF side of a 7778, and Radioshack rabbit ears into the VHF side for my nearby locals. With that set up, I get all CLT and GSP channels consistently except for the distant translator on RF30. Now if only I could get one of those antennas outside ...