[amsat-bb] Placement of Preamp

[Noel Petit]

A far cheaper way is to have individual coaxes for each band. Put a 440 
Mhz preamp at the antenna and don't worry about a preamp for 2m. Good 
low loss cable (LMR400) will bring signals down 50 ' or more at 2M 
without much need for a preamp. Don't use wide band preamps as they are 
subject to so much signal that intermod products will fill all your 
bands. The less you put on the roof the more reliable will be your system.

Remember if it stays up all winter, it wasn't high enough.

Noel Petit
WB0VGI


On 3/9/2019 5:05 PM, W3AB/GEO via AMSAT-BB wrote:
> Frank,
>
> Congrats on your new ears.
>
> The best location for a preamp is at the antenna. That way line loss will be minimized & noise will not get amplified.
>
> Since you have wide band preamp that will hear everything, you'll want a bandpass filter in front of it. The filter should be tuned narrowly to the frequencies you want to work.
>
> This will be difficult due to the single coax feed. But, if you can put the filter at the driven element you should be successful. That would between the diplexer and driven element.
>
> Again, with that preamp you may experience desensing and/or intermod.
>
> Sounds like great place to start. Have fun.
>
>
> ⁣___
> Sent from my two way wrist watch
> 73 de W3AB/GEO​
>
> On Mar 9, 2019, 12:36, at 12:36, WA2NDV <wa2ndv at gmail.com> wrote:
>> Hello all,
>>
>> So on a lark I purchased a Chinese preamp that claims to cover almost
>> DC to light LOL.  seen here
>>
>> On 440 uplinks I was swamping my 2 meter RX so I have a 4 pole 2 meter
>> bandpass filter inline now.
>>
>> My question is where is the best place to place the preamp, output or
>> input of the bandpass filter. Right now its on the input to the filter.
>>
>> Does anyone have some real world experience with this ?
>>
>> I have a single coax dual band antenna feeding a 2/440 duplexer. 2
>> Meter radio is Yaesu FT-817 and 70cm radio is a FT-991A so this filter
>> and amp are fed from the duplexer 2 meter port.
>>
>> I just heard XW-2C at 3 degrees—never heard that before so it is
>> working.
>>
>> I appreciate your comments.
>>
>> 73
>> Frank
>> WA2NDV
>>
>>
>>
>>
>>
>>
>>
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> _______________________________________________
> Sent via AMSAT-BB at amsat.org. AMSAT-NA makes this open forum available
> to all interested persons worldwide without requiring membership. Opinions expressed
> are solely those of the author, and do not reflect the official views of AMSAT-NA.
> Not an AMSAT-NA member? Join now to support the amateur satellite program!
> Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb