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Old 10-Aug-2013, 7:48 PM   #4
tripelo
Senior Member
 
Join Date: Jan 2010
Location: Dallas, TX
Posts: 123
Quote:
Originally Posted by Pete Higgins View Post
...It does look like it could be a re-layout of the Channel Master legacy design, only with a higher parts count. Usually the goal is to make things cheaper by reducing the parts count...
It is not a complete re-layout, looks like a minimum re-layout.

Probably etch was changed only where necessary, i.e. to replace components that may not be available or may be to costly.

An example:

The modular FM Trap was replaced with discrete parts. That did increase parts count.

Quote:
I wonder if Audiovox made them for both Channel Master and RCA?
Could be.

Quote:
... Iím surprised the RCA showed the immunity to overload I experienced.
Yes, interesting.

Quote:
Do you know if the CM-7777 or CM-7778 had onboard voltage regulation?
No the older CM-777x didn't have on-board regulators, or off-board either (CM-0747).

The CM-777x series used a bank of resistors to lower the supply Voltage.

At the left of both images (CM & RCA) you can see those paralled resistors. The RCA has fewer ( count 3 and 2), than the CM (count 5 and 4), probably because the Voltage is regulated down before it gets to the RCA preamp.

The CM-0265 (related to CM-0264) had an on-board regulator.

Quote:
...I donít see anything that looks like it could be a voltage regulator but that was one convenience of the Winegards...
Some of the Winegards have a regulator in the inserter as well as in on the PCB.

Note: The above regulator comments apply only to the CM and WG preamplifiers that I have scrutinized.

Quote:
...did the Channel Master amps have any shielding?...
Yes. The CM-777x has a metal housing, it is fairly tight with respect to RF.

Quote:
...It doesnít hurt that the RCA is available through local outlets like Walmart & Office Depot for less than half the price of the Channel Masters & Winegards.
Yes, good for OTA'ers.

.

Last edited by tripelo; 11-Aug-2013 at 6:30 PM. Reason: Add Note & CM shield comment
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