[600MRG] 630m background noise

[Dave Riley]

Thanks John, I hit the jackpot today..

I was going to add a few turns to the loop but at 5 turns the resonance 
is fairly sharp.

At this rate the -3 db points barely cover the band, no remote tuning 
here..

On one side of the tuning cap I wrap a few turns to the primary of a #75 
mix toroid @ about 5 ohms and enough secondary turns to make 72+/- in to 
old fashioned KW twin lead laying on the ground.. It is truly balanced 
and doesn't pick up much of anything, then terminates to another #75 mix 
xfmr to the receiver. Most noise problems were shack ground noise being 
delivered out to the antenna, big attenuation of that now..

TNX de Dave W1FRV


On 1/30/2023 12:53 PM, John Langridge wrote:
> Dave, my best 472 rx antenna here is similar in design to what you
> describe, but 12 -14 turns on 7 foot spreaders in a square
> configuration and a separate pickup loop about 2 inches from the
> resonated turns.  I also step up the low impedance to the 50 ohms feed
> line with a small binoc transformer..  This setup has been the winner
> for years now here.
>
> anyway, when noise sources are in the null. I usually see S0 to S1
> band noise here.  Signals seem to jump out when propagation is
> reasonable in spite of low S meter readings.  They sound good and
> that's all I care about.
>
> so if I am interpreting your comments accurately you are seeing about
> 1 S unit of noise which is roughly what I see here.
>
> Hope that helps,
>
> 73!
>
> John..
>
>
> On 1/30/23, Dave Riley via 600MRG <600mrg at mailman.qth.net> wrote:
>> The current loop antenna here for 630m is 5 turns of #14 wire, resonated
>> and not shielded in a 5' dia.
>>
>> It out performs previous antennas here so far.
>>
>> With a 50 ohm load connected to the receiver input I set the audio out (
>> no agc ) to 0 db
>>
>> Replacing the load with the loop antenna I get + 7 db of noise with no
>> signals
>>
>> Is this about average for 475 khz?? Does anyone know what to expect at
>> these frequencies??
>>
>> Dave/W1FRV
>>
>>
>>
>>
>>
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