[RFI] SO2R 2nd Harmonic Interference

[myles Landstein]

yup  the battery tender unit’s throw out a lot of  RFI for sure and have also noticed moderate life spans on there switchers. However Their transformer unit   is rfi quiet and lasts a long time.

never tried the  battery minder units.





myles Landstein
myles.landstein at gmail.com



> On Sep 29, 2018, at 6:22 PM, Grant Saviers <grants2 at pacbell.net> wrote:
> 
> I have found the "Battery Minder" products quiet and reliable. Not to be confused with Battery Tender which have had a high failure rate for me.  The Minder brand uses a pulse charge float technology and has recovered partially sulfated batteries for me and has the lowest water loss of any float charger I have used.
> 
> Two are on 24x7 24v 2 to 4a outside (48v x 220AH), one 12v 1a outside on 24x7 (12v x100AH), and one inside 12v 2a on 24x7 (12v x 220AH).  I haven't added chokes on any of them.
> 
> Not cheap but worth it as batteries really last and are always ready to go.
> 
> Grant KZ1W
> 
> On 9/29/2018 13:52 PM, Randall K Martin wrote:
>> I have been trying to solve an interference problem for quite a while here at my QTH. Symptom is that when I transmit on 40M CW, even at QRP power levels using bandpass filters and transmitting stubs, the second harmonic on 20M is a wide signal, covering 30-40 KHz. As per advice given by Frank W3LPL regarding RF flooding, I started searching for an electrical device (probably charger/wall wart).
>> 
>> I eliminated my own home as the source by testing with battery power and all circuit breakers turned off. Through more testing, I found that even at 100 milliwatt output on 40M, I still got the 20M wide band hash, but only when I pointed my 40M antenna at my neighbors house.
>> 
>> Today, I got together with the neighbor and he let me snoop around with a portable Rx. Voila! Culprit is a cheap little trickle charger.
>> 
>> DBT Auto Electrical Products PTE LTD Part no. 021-0123
>> "Household automotive battery charger" 120V input and 12V output at 750 mA
>> 
>> Question: Is there a battery charger that any of you can recommend? I tried wrapping the 12V leads of the current charger roughly 10 x through a large toroid and there was little if any reduction in interference.
>> 
>> 73 Randy K0EU
>> 
>> 
>> 
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