Hi Fred, I am asking the question simply because I was warned by another ham to consider the possibility of a power spike on the feed to the K3 with the choke by another ham. He was not fully sure and suggested that I post the question to the folks who might really know the answer.
Plus if it is good practice to put a CAP across the batteries for the way I am doing my power to help with a clean signal, clean power and better battery life I want use good practice. If I had not been prompted by the ham who suggested a CAP I would have never asked the question. Power is an SGC power cube good for 500w. Antennas are a 2 WL loop for 160m and a dipole and the shack is on the second floor. Maybe the answer to the question is so obvious that it just shows my total ignorance. Hey but I do learn slowly at times :-). Example I now work split and if you remember those posts from me on that topic I think everyone wanted to hit me in the head with a baseball bat. Like I indicated right now everything is working real good and I have no problems, but I dont want to be in the process of creating new ones. Cheers Don ~73 Don KD8NNU On Sun, Feb 5, 2012 at 12:32 AM, Fred Townsend wrote: > Hello Don: > If you have cured your RF problems I'm not sure why you are asking > your > questions. > In general adding a choke or capacitors to your power lead shouldn't > hurt > anything so give it a try. I will add detail to your questions below. > BTW > you should indicate how much power you are running and where your > antenna is > located relative to your K3. FT > > -----Original Message----- > From: [email protected] > [mailto:[email protected]] On Behalf Of > [email protected] > Sent: Saturday, February 04, 2012 7:03 AM > To: [email protected] > Subject: [Elecraft] RF on power to K3 question > > Dear Group, > > I have determined that the majority of my RF shack problems were > related to RF on the power lead to the K3. Winding 7 turns thru a 1" > clamp on #31 ferrite has cured the symptoms. With this choke in > place everything is even happy on 160m. > > So let me explain how I power the equipment and then ask about putting > a CAP > across the power. > > The radio and SGC power cube amp are powered by 5 batteries connected > in parallel. I use a very small battery tender connected at all > times to keep the batteries at a full charge. When using the amp I > also float a battery charger set to its mid range position with a max > of 15 amps of charge to help maintain the system. From this > perspective it works real well for powering the system. But I wanted > to be sure that everyone > understands how I power the system as I get to my questions below. > > Plus there is the normal AC stuff like the PC and so on. > > All equipment is grounded to a single point ground on one of the > negative > posts of a battery. > > Do you have an earth ground? That is a ground rod. Depending on your > setup > that may or may not help. FT > > So now to the RF problem. If you have followed earlier posts I have > been > chasing RF in my shack for quite awhile and finally started playing > around > with a clamp on meter and that is what tipped me off to the power feed > of > the K3. > > With the power feed determined as a problem (there still could be > more). One of the tests I did was to remove all of the chargers and > disconnect all > the AC equipment and connect the amp output directly to the dummy > load. RF > was still present even after I attempted to remove all influences to > verify > if something was putting this on the power leads. So now I believe it > is there natively when in TX and is not from a charger > or PC or other antenna. > > That suggests you may have other, as yet, undetected problems. FT > > Based on my reading about chokes, I put 7 wraps in the 1" big snap on > ferrite. This killed the RF and like I stated in the opening > paragraph with > everything reconnected again the system is now happy at 160m. It now > actually works real well. > > > This is good. FT > > In discussing what I found with others, I have learned that batteries > are > not filters and all the HF energy goes right thru them. > Recommendations have been made to put a ceramic capacitor across the > batteries to filter the HF out. I also have been cautioned that there > may > be a problem with a choke on the power feed to the K3 that could put a > power > spike on the feed line that could do damage when turning the radio on > and > off. > > So here are the questions. > > Can the choke cause a problem with power spikes that could damage the > K3. > > No. FT > > Should a CAP be placed across the batteries to filter out the HF. If > yes > how do I determine what size. > > Adding a cap won't hurt but it probably won't help much either. It > might > make your battery tender happier. It should be pointed out your K3 > already > has bypass caps across the input power leads. Take a look at the > schematic. > As for value it is not critical as long as it is a ceramic cap, 50V or > greater. Since you are working 160M I would start with an 0.1uF. It is > useful to have a combination of values. If I were working 40M I would > add a > 0.01uF and for 15M and above a 0.001uF. Put them all in parallel. FT > > Also if yes for the CAP will this improve battery life. > > > No. FT > > Also if yes could the CAP have influence that could negatively effect > my use > of chargers for floating power. > > Again, no. FT > > Again as always, that in advance for your help from this great group. > > Cheers > Don > > > ~73 > Don > KD8NNU > > ______________________________________________________________ > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[email protected] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
