Topband: DX Engineering Preselector

[ZR]

I understand the process quite well but I dont understand the need for such 
a device on a Beverage the large majority of the time. The only time Ive 
used a preamp is on those quietest of nights where only 9-10dB of gain from 
a preamp with a 1.5dB NF brings a ghost of a signal out of the noise. I 
didnt have to buy it either as I have the equipment to design, build, and 
test to my own stations needs. And not a generic catalog item such as the 
RPA-1 which amplifies everything from LF to VHF and dumps it all into your 
receiver including everything from the BCB. No wonder it and the limiter are 
overloaded. The rather generous specs are for a single signal only, not 
thousands of them.
At the very least you should have a 160M bandpass filter, or a BCB filter if 
you dont want to bother switching individual filters per band, ahead of the 
RPA-1. Note also the instructions include methods to reduce gain, not all of 
which I agree with.

Carl
KM1H




----- Original Message ----- 
From: "John Harden" <jhdmd at bellsouth.net>
To: "ZR" <zr at jeremy.mv.com>; <topband at contesting.com>; "Richard Jaeger" 
<k4iqj at mindspring.com>
Sent: Friday, August 24, 2012 4:47 PM
Subject: Re: Topband: DX Engineering Preselector


> Carl,
>
> I bought the DX Engineering device because it has the best third order 
> intercept. Just see W8JI's web site. Tom has a chart that compares TOI's 
> for various devices. I trust his meaurements because they are based on 
> facts and knowledge of the RF arena. They are not opinions and assertions 
> as one hears often on the reflector...
>
> When comparing receivers it tells us how well devices separate two closely 
> placed signals. As you know it is a calculated value based on the
> plot of Output power in dBm vs. Input power in dBm. It cannot be measured 
> like selectivity.
>
> The IP3 really tells us how well two signals 3-5 kHz apart can be copied. 
> Tom's values are good enough for me.
>
> This device replaces an ICE 160 only receive preamplifier.
>
> 73,
>
> John, W4NU
> K4JAG (1959 to 1998)
>
> On 8/24/2012 4:19 PM, ZR wrote:
>> Why do you feel it is the best?
>>
>> Without knowing the circuit of the limiter I can just surmise that it 
>> uses diodes or other non linear device to clip the input above a certain 
>> level. Try it ahead of the preselector where the signal levels are less.
>>
>> Carl
>> KM1H
>>
>>
>> ----- Original Message ----- From: "John Harden" <jhdmd at bellsouth.net>
>> To: <topband at contesting.com>
>> Sent: Friday, August 24, 2012 3:44 PM
>> Subject: Topband: DX Engineering Preselector
>>
>>
>>> I just put in the above as it is the best one out there... However, when
>>> I put in the Array Solutions RF Limiter/Arrestor between the preselector
>>> and the K3 I get distortion in the signals. Any comments out there?
>>>
>>> The RX antenna is a Hi-Z 8-Circle array.
>>>
>>> 73,
>>>
>>> John, W4NU
>>> _______________________________________________
>>> UR RST IS ... ... ..9 QSB QSB - hw? BK
>>>
>>>
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>>
>>
>
>
>
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