Sunday, November 17, 2019

On the air with new antenna!

You can see our new 86 ft inverted-V-non-resonant dipole on top the "Whitfield" building at Evergreen Woods, our new QTH.  Fed by 400 ohm ladderline to our 2nd floor apartment at the right, it was a long slog to get installed.  Lots of help from friendly facilities staff, however.  A 4:1 balun connects our ladderline to either the Flex-6500 directly or through a Heathkit SA-2060A Antenna Tuner.

First test shows it's a good 40 M antenna, easily matched with the built-in ATU of the Flex-6500.  Other bands can be a challenge, but the SA-2060A will tune this system over 160 - 6 M -- at least if you're willing to crank those knobs!

My first on-air test was on 80 M with the SA-2060A.  This is a difficult match, because the 86 ft dipole is close to a quarter-wave at 3.6 MHz.  Does it work?  I set it up with WSPR at 5 W transmit power to see what came back.  Partial results of the first few minutes:

Timestamp Call MHz SNR Reporter RGrid km az
2019-11-18 02:36 AA6E 3.570022 -24 HB9TMC JN46lj 6279 55
2019-11-18 02:38 AA6E 3.570021 -24 PA0O JO33hg 5815 48
2019-11-18 02:36 AA6E 3.570022 -24 TF1VHF HP84wl 4091 34
2019-11-18 02:34 AA6E 3.570025 -27 KA7OEI-1 DN31uo 3263 284
2019-11-18 02:34 AA6E 3.570023 -18 VE6JY DO33or 3250 309
2019-11-18 02:38 AA6E 3.570022 -27 KX3DX DM79 2723 276
2019-11-18 02:34 AA6E 3.570022 -25 N6GN/K DN70ll 2697 279
2019-11-18 02:34 AA6E 3.570022 -26 N5SNT EL09wq 2618 249
2019-11-18 02:38 AA6E 3.570018 -25 KI5WA EM11jk 2435 251

So I think we pass.  Best DX is HB9TMC in Switzerland, 2279 km = 3901 miles, with a Kp index of zero suggesting OK propagation..

I had been worried about interference from our building HVAC and other systems. It's there, but so far it's no show-stopper.  My first tests, inside the apartment, were a total disaster, but being 20-25 feet above the roof gets rid of most of it.

Thursday, August 15, 2019

Casing the Environment

We have completed our move to Evergreen Woods, at least to the point of unpacking many of our boxes of "stuff".  Time to check out the Electromagnetic Environment. 

It's not all good or all bad. The fact is that we're inside a fairly large complex of 249 apartments and commons buildings.  We are in a rural/suburban setting, but the buildings have complex systems for HVAC, data networks, and power distribution.  So we expect a somewhat challenging RFI situation for HF.  You see one example above.  All the peaks (separation ~106 kHz) seem to come from one source that probably gets here via the AC power line.

I am using a Flex 6500 SDR as an RFI receiver with an EMCO 6502 active loop antenna.  The antenna sits at my new second-floor operating position, not far from some metal objects that probably affect the measurements.  The proposed antenna site is on the roof above the third floor, which is probably (hopefully) a somewhat better location!

Zooming in to get some finer detail, we see three of these peaks in the 40 M band:

A working hypothesis is that these may come from the building elevator system, with the glitches occurring during elevator motion.

This 106 kHz frequency comb is not quite fatal for ham radio, because in most cases you can choose an operating frequency away from the RFI.

There seem to be several sorts of RFI that become visible at various operating frequencies and various times of day.  Some of them are quite broad (no narrow spectral peaks), and some are impulsive, like ignition interference or PLC-type digital signaling.  The Flex 6500 has several noise blanking options that are at least partially effective.

The antenna is probably going to be placed above the flat roof shown below:

A diagonal run of about 100 ft looks possible, using 20 ft masts.

Stay tuned for further developments!

Wednesday, July 03, 2019

Migrating from Branford to North Branford CT

AA6E moving on, see my web site:  The big shack picture is fading into history.

We are thinking about quality instead of quantity here, as far as the ham activity goes.

Saturday, June 15, 2019

Beginning of the End for FB

I killed off Google+ last year and started a little tradition.  Today, I've killed off Facebook.  At least, I'm deleting my personal account at FB.

Why would I do that?  Glad you asked!

  • Facebook has a near monopoly position in social media.  Benefiting from the "network effect" ("value" increases as the square of the number of users increases), FB has triumphed over all its competitors in the medium-long-form sharing segment.
  • Monopolies are generally bad.  Anti-trust law evolves much more slowly than technology.
  • Facebook governance is effectively in the hands of one individual, who shows little appreciation for the public interest or the social impact of his company.
  • As a "free" service, users are persuaded to share way too much data with the service, often thinking it's just a matter of keeping up with friends or touting our lifestyles to the world.
  • Facebook makes lots of money by packaging and reselling our data to commercial or political interests.
  • For many users, Facebook is addictive.
  • The Facebook model especially encourages evil forces (read Russia or US ultrapartisans) to influence our political system, spreading rumors and all kinds of divisive false information.
  • Facebook has very little "quality control".  There are weak attempts to suppress pornography,  political abuse, and illegal conduct, but these are not very effective.  For FB, quality control means reduced profits.
  • Apart from the shady business model, Facebook has a serious "signal to noise" problem.  Over time, your friends (and friends of friends) can easily overwhelm your news feed with irrelevant and distracting (to you) material.  As a reader, you have little control over what you see in your news feed.
  • The selection algorithms are obscure to users.  They are meant to keep you engaged and clicking, but not to be useful.  It can be really hard to return to a particular item you remember seeing a few hours ago.
None of these points are particularly original, I know.  But you did ask!

I'm still here on Blogger (another "free" service).  It's part of Google, and Google is another collector and reseller of my data, I know.  Especially when I use Android, Drive, or Maps, or many other services.  I use Twitter, too.  Twitter is short form (mostly), and I seem to be better able to filter what I read.  And there's Amazon, and there's even Reddit, and more.

Saturday, April 06, 2019

Antennas, cheap

We are going to be taking down the ham antennas, because we're moving to a retirement community.  This happens.

On the positive side, our new community is interested in supporting amateur radio (to some extent?), and we may have a chance to develop a new "farm".  See my article on ham radio in retirement communities.