[600MRG] Buying "NOS" line filters?

[Neil Klagge]

I recommend a small active loop such as the  Wellbrook type loops for receive on LF/MF.

De w0yse
Sent from Neil's iPhone

On Jan 13, 2025, at 06:52, Dave Riley via 600MRG <600mrg at mailman.qth.net> wrote:


When we get near the bottom of our noise QRN interference then it comes time to see the ether noise and at 630m there is a LOT of noise here. I can depend on a differential of antenna noise on 630m when short/no shorting of the antenna port averages around 9-12 db ..
The question now is how to isolate the various sources of noise.. Do I use a small loop or an E probe?
Have been using SDRplay for some time and it seems as good as a spectrum analyzer.
I can get rid of some noise that has nothing to do with the sigs inside of 630m and the SDR is sure help to find the sources..
What to do??



On 1/13/2025 7:34:33 AM, Paul N1BUG FN55mf <paul at n1bug.com> wrote:

Thanks Tom. Your knowledge is always appreciated.

I've ordered one to try.

73,
Paul



On 1/12/2025 1:37 PM, Tom W8JI wrote:
> Transient abuse or lighting damage might be an issue with used filters.
> Physical damage might be a concern, but you could see that.
>
> Given the high quality parts used in power line filters I wouldn't worry
> a bit about age or handling issues.
>
> 73 Tom
>
> On 1/12/2025 5:02 AM, Paul N1BUG FN55mf wrote:
>> Does anyone have thoughts on possible risks of buying new, old stock AC
>> line filters on eBay? I am tempted as I see some good deals but I wonder
>> about aging of high value capacitors (1.5 uF, .47 uF). I also wonder
>> about possible damage from dropping or sudden impact since they probably
>> use ferrite for high value inductors (47 mH). These filters that have
>> good performance at LF and into VLF are very different in terms of parts
>> values, size and weight from the ones I have experience with at HF, VHF
>> and UHF frequencies. The more I think about it, the more I think paying
>> almost twice as much at Digi-Key or Mouser is probably wise.
>>
>> 73,
>> Paul N1BUG
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