[Elecraft] K3 and Preamp

[iain macdonnell - N6ML]

Hi Ted,

I didn't say that the pre-amp isn't worth the money - I just said that
supplying more noise to the ears isn't a good justification for it.
It's well known that the K3 needs a pre-amp for effective weak-signal
work on the higher bands, but it's not (primarily) because it makes
the noise louder - it's because it raises the signals (from the
antenna) above the receiver's internal noise.

73,

    ~iain / N6ML



On Fri, Sep 5, 2014 at 1:54 PM, Dauer, Edward <edauer at law.du.edu> wrote:
> Aware as I am that the word ³data² is not the plural of the word
> ³anecdote,² I can offer a subjective anecdote to the contrary:  With the
> PR6-10 in the RX Ant line  of my K3, there are CW signals I can copy
> (barely) which I cannot hear at all with the preamp out of the circuit,
> regardless of the RF and AF gain settings.  I can¹t explain it and I don¹t
> have the equipment to do any objective measurements; but it is the case.
> I have found the pre-amp to be worth the money.
>
> Ted, KN1CBR
>
>
>
>>------------------------------
>>
>>Message: 25
>>Date: Fri, 05 Sep 2014 10:34:17 -0700
>>From: Jim Brown <jim at audiosystemsgroup.com>
>>To: elecraft at mailman.qth.net
>>Subject: Re: [Elecraft] K3 and preamp
>>Message-ID: <5409F419.9050500 at audiosystemsgroup.com>
>>Content-Type: text/plain; charset=windows-1252; format=flowed
>>
>>On Fri,9/5/2014 9:59 AM, iain macdonnell - N6ML wrote:
>>> That doesn't justify a pre-amp. If you want more acoustic noise, just
>>> turn up the AF gain. The only reason (I can see) to use a preamp is if
>>> the receiver internal noise level is higher than the atmospheric noise
>>> (coming from the antenna).
>>
>>Right.
>>
>>> If the noise level perceptibly drops when
>>> you disconnect the antenna, a preamp isn't going to do much for
>>> you....
>>
>>Perceptibly is not the right word if you care about weak signal work.
>>The difference should be at least "twice as loud" when the antenna is
>>added, which corresponds to about 10 dB.  Use the K3's internal audio
>>voltmeter to determine this.  Turn off AGC, with the antenna connected,
>>calibrate the dB readout to zero following the instructions in the
>>manual, then remove the antenna.
>>
>>73, Jim K9YC
>>
>>
>
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