[JMS] Recently acquired James Millen Preamplifier Model 92101withplug-in coils

[john]

I agree with you Don.... I've found that these preamps are useful on 10m
(when 10m is open!) but not particularly useful elsewhere. On 10m  it was
very useful however!

John K5MO


At 04:21 PM 12/27/06 -0600, you wrote:
>The problem with preamps is they will amplify the noise as well as the 
>signals.  My feeling is if you can hear them then an amplifier probably 
>won't make it a more pleasurable experience.  Often times we get 
>"S-Meter Envy" (me too) and the higher the reading the better the 
>receiver.  I'd prefer an S6 signal with little noise versus the same 
>signal with an S9+20dB strength and an S7 noise level.  However, we do 
>know that the RF related noise level in any receiver is primarily due to 
>the first stage of amplification.  So if you have a low noise amplifier 
>up front it could and will provide a real service in your receiving 
>ability.  On VHF and above they will often put the preamplifier at the 
>antenna.  That's because as you go higher in frequency the thermonic 
>noise generated in the coax can be high enough to cause adverse effects 
>in the whole receiving RF chain. Thus putting a low noise amplifying 
>stage close to the antenna is a real benefit.
>
>The 92101 has a pretty good Noise Figure for a tube ampilfier of it 
>vintage.  On cheaper receivers of the 30's and 40's it could make the 
>difference between hearing them or not.  I've found on my HRO it was 
>helpful on 10 meters with weak signals.  A well tuned HRO on 20 or 15 
>meters probably would not benefit much from the 92101.
>
>
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