[Boatanchors] line cord question

[Bill Cromwell]

Bob!

Yes..IEC. I got onto those when my cheep, nasty replacement PC power 
supply blasted my radios. I added the missing parts and tamed the power 
supply. Then I found I could buy those connectors with the filters about 
as cheap as I could build them and not have to build them. It had not 
occurred to me to mount them externally to a boat anchor in a minibox 
but it has now:) Maybe arrange it so the minibox sits beside the boat 
anchor and includes a power switch.

It isn't practical for tube transmitters of more than a watt or two 
output but I have had great luck stopping conducted line noise by using 
batteries. Vacuum tube receivers up to six of so tubes don't need much. 
I started down that trail when I wanted to operate my command receivers 
during power outages with no dynamotors.

73,

Bill  KU8H

On 2/18/19 11:26 AM, Robert Nickels wrote:
> On 2/18/2019 9:59 AM, McDonald, J Douglas wrote:
>> The only thing that helps is a TRIfilar choke with all three line cord 
>> leads, with 0.01 uF safety caps connecting all three together at the 
>> line cord end,three .01 caps grounding all three at the chassis end, 
>> and a TUNABLE variable cap across the chokes
> 
> I agree that safety capacitors (X type from line to line and Y type from 
> line to ground) won't do a lot if you have conducted EMI on the AC 
> line.  I've never done the tunable thing, but I nearly always use a 
> filtered IEC power entry module in homebrew gear, and have had good luck 
> also mounting them in a small enclosure with a receptacle for the radio 
> to plug into (also a good place to add fusing for those with the 
> dastardly fused plug).  Here's an example of a stock Schnaffner product 
> that is a little over $6 from DigiKey:
> 
> https://www.digikey.com/product-detail/en/schaffner-emc-inc/FN9222R-15-06/817-1449-ND/1929030 
> 
> 
> Not only can you be sure the proper components are used in a commercial 
> module but you can view the datasheet from the link above and see the 
> attenuation curves.   I bought a bunch from MPJA when they were a buck 
> apiece, and while those are no longer available, this filter module 
> looks interesting because it incorporates a two-stage filter for about 
> the same price:
> 
> https://www.mpja.com/IEC-Power-Inlet-Module-RFI-Filter-Switch-Fuse-Holder/productinfo/33931+FH/ 
> 
> 
> These modules are easy to integrate into homebrew gear;  you just have 
> to get creative when applying a filtered module to a boatanchor radio. 
> But they absolutely work - totally quieted down a cheap PC replacement 
> power supply where the "cheap" came at the cost of eliminating the AC 
> line filter!
> 
> 73, Bob W9RAN
> 
> 
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-- 
bark less - wag more