RCA preamp with seperate inputs

[southofi-10]

Well I guess this is original.A RCA mast mounted preamp that has seperate or combined inputs for vhf and uhf.
It says on inside instruction that this amp is made specific for digital channels.Unlike the other older models like channel master and wineguard that were made for analog.
And yes,I do understand that just as long as it picks up the right frequency it'll work.I have several antennacraft and a wineguard working as we speak.
I just wanted to put this out there..It can do away with a combiner and it's fairly cheap.Being sold by radio shack on ebay. Usual gain as most smaller amplifiers.Figured it's worth a try.
I'll be adding another UHF soon,so I went ahead and got this one.
If you want to see them,just go to ebay and put in preamp.

 

[FaT Air]

It says on inside instruction that this amp is made specific for digital channels.Unlike the other older models like channel master and wineguard that were made for analog

Advertising Hype. They are designed for RF. RF circuits don't care what type of modulation is employed.
The ONLY specification that could be conscrewed as 'digital' is the reduction in the frequency coverage. (from the original band to the somewhat smaller digital "TV" band - loosing 692Mhz and up. MOF, that could help get a lower noise figure)
I read a review of a GE amp not long ago, and it was cheap, that appeared to copy the circuitry used in the old(dual input) ChannnelMaster 7777. Seemed to me that the performance was = to or a bit better than the CM amp. (less band pass- lower noise?)
I want to check one out as I'd used the 7777 many times in the past.
Think in the article/ review I read they were also at Lowes and other merchandisers.
Edit: thought it was at digitalhome.ca but I dot't see/ can't find/ it.

 

[southofi-10]

Walmart has the rca for 21.06 online!!!!
They have a GE video amp also.Works with video and antenna eqipment.
They actually have alot of amplifiers including eagle aspen as a good price.
I didn't know GE was in the antenna amp market

 

[mike123abc]

If you want to combine an UHF and a VHF antenna a splitter used in reverse will work fine. If you are trying to combine 2 full range antennas and want one for VHF and one for UHF they make combiners for that that filter out the UHF on the VHF in and vice versa.

 

[FaT Air]

Found it. http://forum.tvfool.com/showthread.php?t=13530
RCA TVPRAMP1R If it works as well as the old CM 7777 it's one heck of a deal at $21.06. About 1/4 what I paid for the 7777's.

splitter used in reverse

Only if you can 'live with' less signal strength. Each port on a typical splitter has nominally 4 to 5 db loss**. And could be more if same freq but a phase difference is introduced. Minimize this by mounting the antennas above/below one another and use equal length coaxes from/to balun and splitter. More ideally, the feed point of the antennas would be vertically inline.

If Wanting to 'stack' two identical antennas to get better performance(gain) on a channel or single band, the splitter method makes the gain an overall loss, better to use a 'phasing harness' or get the bigger antenna.

If two antennas are wanted to be used for Different bands or directions, same applies. Equal length coax.

**The 'key' is this: Take into account the losses you're also adding to the 'system'
If first you have a +12db gain antenna. Your gain is 12 db.
'Splitting in' a 2nd antenna (+12db) does not result in 24db gain. Doubling is only 3db. So the result 'could be' +15db. But if using the splitter to combine them the result is +15 - 4(or 5)= +11(or +10)
Or 12-4(5)=8(7) 8(7)+3= 11db(10) 1 to 2db loss when adding the 2nd antenna.
A 'stacked' 2nd antenna, utilizing a phasing harness, will be closer to the theoretical (12+3=) 15db gain result.
GE:
Don't think GE is, in the consumer electronics market, producing product anyway. Think they turned into a rebranding company in the early 90's. Think the only product GE produces/builds themselves anymore are jet engines.

 

[. Raine]

Right, Fat Air, RCA and GE consumer electronics was taken over by Thompson Electronics in the 1990's.

 

[southofi-10]

Phasing harness.....now thats two words ya don't here much anymore.
What would a guy make these with?
Since the antenna spacing might depend on the channel and type of antenna your using.
I remember seeing some "very" old vhf antennas in the area and the had a phasing harness with the output in the middle of two identical antennas.
Some of these old ideas would work great today.
And no--I never use splitters backwards because of the loss.I either use a combiner ( I only have 1 set off stacked antennas) or I amplify each antenna seperate,then combine.I find the later works well,but can get costly.My amps are located in my workshop where the two towers are also located.

 

[FaT Air]

I remember that for two 50 ohm antennas, the coax required is 75 ohm and the length of each 'leg' is an odd number of quarter waves in length. Also the velocity factor has to be included.
(Had 'phased' CB whips on the vehicle BITD.)
1.5 x 75 is 112.5. What coax is 112 ohms????
300 . 1.5 = 450 Seem to remember "ladder line" from reading some ham (amatuer) stuff.
10ft piece on 'bay
1/2 wave of ladder line between antennas. Balun connected midway.
2952 x (Velocity Factor) / Frequency (MHz) = Length in Inches

Somthing else I found, some formulas http://www.kcvhfgridbandits.com/linked/phasinglineconstruct.pdf