Monday, August 3, 2015

The War on RFI: Mission Accomplished



I am happy to report, I have quashed the RFI enemy, and we have entered a peace keeping role!

After completing the video and post yesterday regarding my new balun, I still was having some thumping in my powered speakers.  I thought it was coming from my mixer as the issue went away when I unplugged the speakers from the mixer.

In all of my attempts to fix the problem, I took apart the subwoofer/amplifier of the speaker system and found a grounding point that I used to tie to the station ground (ground lug on my power supply). After all, all the wisdom is "ground everything to a single point."  Well it turns out, this was bad advice in this case!  I was about to give up when I just ripped the wire out and sure enough, that cleared up the last bit of RFI!

Such a great relief to know I don't have to mess with that anymore after all the hours I've spent routing and re-routing wires.

Moral of the story? Take your time, attack the problem one step at a time, and eventually you'll figure it out!

Saturday, August 1, 2015

A coaxial air-core balun

Today I posted a video describing an air core balun I built:


I wanted to post it here so that you guys could see it as well in case you don't subscribe to my Youtube channel (you should be!).

It is made of 25 feet of RG-6 coiled around a 5 1/8" form.  The form is a 4" PVC pipe coupling (it measures 5.125" on the outer diameter) and the coax is the "fancy" quad shielded coax.  I got both at Lowes but you can find them at Home Depot or whatever your local big home improvement store is.  The coax was from bulk and 25 feet was only $7.25 (29 cents a foot) and the coupling was $2.10.  Of course cost to put it together depends on your junk box - I had a pair of Amphenol PL-259s on hand so that's what I put on.  I followed the method I showed in a previous post for connectorizing RG-6.

Initial results seem to show a reduction of RF in the shack but I'm still having problems with my powered Logitech speakers making thumping noises when I key and unkey the radio.  It must be coming from the mixer board because when I have the speaker input unplugged, there's no noise.  Tackling RFI is no fun.

So if you guys have any suggestions aside from ferrite beads - already have those everywhere - let me know!

Monday, June 22, 2015

What did you do this weekend?

Well I made APRS contact with the space station so.... That's cool right!
I also tried for a few other satellite passes on SO-50 and FO-29 but they were all bust. In fact, the last FO-29 pass, my lithium battery I use for my 817 took a huge dump on me and completely died.  I wasn't sure it would even recover during charging but eventually it took the power and charged back up, but I'm sure its on its last legs.  That makes 3 LiPo batteries I've killed off now.  I should probably be more careful.

6 Meters was also open a bit on Sunday and I made quite a few QSOs on CW, SSB, and JT65.  It really is something when 6 is open.  No noise at all, and even with a wonky antenna (like a 20m hamstick) the contacts come pretty easily.  I might have to look at putting up something more suitable for the band if it keeps opening up like this!

Fun weekend anyway, hope yours was good too!

Thursday, June 18, 2015

Proof is in the pudding - or the logbook in this case

I woke up this morning and grabbed my phone as usual to read my emails I got over night and all that jazz and decided to check the satellite passes for the day.  I checked FO-29: nothing today wort trying, AO-7: probably not worth trying either, mode J is far easier, SO-50: OH DANG! there's a pass in progress!  She was about 1/4 of the way through the pass so I jumped out of bed, threw on some pants and grabbed the Elk, TH-D72 and dumped my connector adapters out, found the SMA-UHF connector and wham, bam, thank you ma'am I was ready to go.

I got out to the balcony, found the sat and worked a guy in TN in no time flat!  Oh if I had only known working SO-50 could be that easy!  It sure helps when you have an antenna that is put together right.  Its hard to believe I managed any contacts at all now that I know what I do!

Wednesday, June 17, 2015

Tuning an Elk....or something like that

You all certainly remember my escapades from a few weeks ago working FO-29 from the roof of the parking garage.  Well it turns out I was having a few issues with SWR but I just chalked it up to crummy coax.  Then I tried to work SO-50 in the parking lot at work with one of my co-workers but it turned out to be a terrible demonstration too!  And finally, this last week, I gave FO-29 another shot from work and it too was a general failure with reports of a "weak" signal.  Now, don't get me wrong, 5w into a busy satellite isn't "big gun" at all and I'm used to weak signal reports but I should have been doing better.

So I threw out a quick feeler on the contest group to see if anybody had an SWR meter for VHF/UHF.  Sure enough, someone had one to loan and I picked up a Rig Expert AA-600 the same day.  It's a pretty slick piece of kit!

I put the ELK on the meter and sure enough, SWR was way out of spec.  No amount of fiddling made any difference.  I couldn't figure it out.  I went online and started checking some pictures and noticed something.  I was pretty sure my antenna elements were not on right!

Sure enough, the guy who sent me this antenna must have put it together wrong and since I didn't know any better, I did too!  He had put all the elements on one side on the same boom (i.e. all the elements on the left were on the top boom, and all the elements on the right were on the bottom boom).  They should have been staggered - every other element on the opposite boom.

I sat down, swapped out the screws, and hit the meter... Eureka!  The SWR showed <2:1 on both bands finally.


While I was at it, I figured I'd put my HT antennas on the meter too: 
Diamond SRH77CA (that doesn't look too great...)
Much better on 70cm...

TH-D72A stock ducky (YIKES!)

Ehhh pretty bad here too
So interesting results.  I would have expected the Diamond antenna to be a lot better on 2m.  I suppose it could be the bevy of adapters I needed to get the thing on the meter to begin with.  It does seem to work pretty well anyway. 

So that's it for now, listen for me on the next satellite pass!

Monday, June 8, 2015

RFI-Gate 2015!

You remember when I mentioned I was getting into something on 80m in my last post?  Well, it turns out it was my system: my subwoofer for the surround system in the living room was going boom-boom and once I figured that out, I thought I was home free!  Yet, it turns out, I was not.  The Reddit round table (or whatever it is called) on Sunday night was in full swing and I had just finished contacting a guy in Arkansas on 40m when my wife heard a knock on the door.  I had my headphones on so I doubted her but sure enough, a glance through the peep hole and there was someone there!

Turns out its the guy from the 2nd floor apartment downstairs.  Yep, you guessed it, I was getting into his system.  He's is a young guy, my age probably, and interested in tech stuff so I invited him in to see the station and my antennas and since he was nice about things, I offered to help solve the problem this week.

I dug through my junk drawers and found a couple snap on ferrites and when I got home from work today, I went down with him and had a look at his setup.  I was getting into his powered computer speakers so I knew I could take care of things if I got the ferrite in the right spot.  A couple quick trips up and down the stairs, and phone calls later, and we had squashed out the RFI on 40m.  Unfortunately 80m was still causing problems and I had run out of beads.  I never have been super active on 80 so I don't consider it a total loss and I may just give up on that band.  Maybe I'll try low power CW only and that might keep me out of his system.

Just keep this in mind when dealing with RFI complaints - if you can make it so you can both be happy, all the better!

Sunday, June 7, 2015

80m = no good. 6m = good.

We finally finished unpacking the living room and kitchen this weekend so we took the boxes and materials back to our storage unit and while we were there, I grabbed my other 2 hamsticks I had in a box there for 40 and 80m.

I got right to tuning and much to my surprise, the whip I was using on 20m managed to work perfectly on 80 and 40m, giving me a low SWR match on both bands somewhere near the middle of the band.  Unfortunately the bandwidth on both is too short to go without a tuner near the ends of the bands but it isn't anything my 590 can't handle.

Things seemed to be working pretty well on 40m but it was the middle of the day so I didn't really play around with it too much.  I got the 80m antenna up and it too seemed to be working ok but when I took my headphones off I noticed I was getting into something and I think it wasn't my something... so I think I'll have to put off 80m for now!  It is no loss, 40m will be a lot of fun itself and I can probably squeeze out 30m too.  

I did hop on a bit Sunday morning and I saw spots on the DX cluster for 6m so I tuned around a bit with my 20m stick tuned up on 6 and heard a few stations from the Midwest popping up but I was unable to raise any on voice or CW, then I remembered someone mentioning they were running JT65 on 6m and tuned up to that part of the band and sure enough, I heard the familiar tones of our favorite JT mode.  I walked away with a handful of QSOs from 9 and 8 land at 20w, which is pretty cool!  6m really is a Magic Band and if you have not tried to get on before, I really recommend it!  It doesn't take much antenna; when the band is open, its open so just about anything will work.  So keep an eye on the cluster and don't be afraid to hop on sometime.