RV Net - 9/24/2020

Here are 5 audio clips from the second hour of the 9/24/20 (East-Central-Canada) RV Service Net on 7.191 MHz, recorded from my Flex-3000 transceiver in Baton Rouge. Any long time segments with no readable audio have been shortened or edited out. The stations heard are identified above each audio clip. 

John WA5MLF

AI1N

W8OI, WK1F, N4JLR

N4JLR, W8OI, WW1SS

K9JWJ

K9JWJ, W4BXI (via N4GYN), K4ICZ, W4OWT

WU5E (Korea) to RVNet -- 9/17/2020

 WU5E checked into the RV Net from South Korea using an Internet remote connection to his Flex-6600 in Tennessee. Below is part of his exchange with net control W4BXI. The audio was recorded by WA5MLF in Baton Rouge on his transceiver.

The figure below shows that WU5E and W4BXI use the Internet to connect to separate transceivers remotely. There is no direct Internet connection between their computers.

Sloper Antenna for 20 m thru 10 m

A sloper dipole antenna is planned for evaluation at W4UOA to supplement the two horizontal dipoles and one horizontal loop antenna. The hyperlink in the previous sentence has a very nice analysis of the sloper antenna. I offered to do some modeling of the new antenna at W4UOA, and some results are presented below. The antenna is sized (length = 29 ft)  according to W8JI guidelines for a multi-band dipole. The radiation plots are oriented for a westward direction of greatest gain. The heights of the antenna ends and the slope angle are arbitrary starting points. The antenna is to be fed with 450-ohm balanced line that transitions to 50-ohm coax cable thru a balun.

Click on any plot to magnify.

This plot shows the total gain (horizontal and vertical polarization) of the antenna at 14.25 MHz in the horizontal plane. The blue curve maps the gain (dBi), with the scale progressing outward from the center of the plot. The labels around the plot are azimuth, like compass bearings, going clockwise around the circle. 0º is North. The antenna is in the plane oriented east-west. The maximum gain is 2.25 dBi at azimuth 334º.

This plot presents the total gain in the vertical plane. The labels around the circle are elevation (above horizon) angles. This shows the maximum gain (2.25 dBi) occurring at 46º at azimuth 338º.

This plot shows the vertical gain in the horizontal plane. The maximum gain is 2.11 dBi at azimuth 270º and elevation angle 72º.

Here is a 3D view of total gain with colors to signify the gain according to the scale at the left side of the figure. The slanted white line represents the antenna structure. The web link at the top of this article has a very nice animation of 3D and 2D views showing how the gain varies with the angle of the antenna from vertical to horizontal. The author of the article uses the same modeling software as I have used for these plots.





The W8JI article with guidelines for multi-band dipoles recommends balanced feed line of 300-ohm characteristic impedance.  Since Carl has 450-ohm balanced line on hand, I ran comparisons of the design using both feed line types, for the frequency range of interest -- 14 to 30 MHz. The modeling software generated tables of data including: SWR, gain F/B ratio,impedance (R, X, |Z|, phase). I made graphs to compare the SWR vs frequency and impedance (magnitude) vs frequency for both feed line impedance values. The graphs below show that for most frequencies there is not a large difference between the results of the two impedance values.  The SWR data are based on a 50-ohm source impedance. These results do not include the coax cable that will extend the balanced line to the antenna tuner. That detail can be added to the model at any time.

I would prefer to start these graphs at 14 MHz, but I don't know how to prevent Excel from starting at zero on the x-axis.

It will be interesting to see how this new antenna performs at W4UOA in comparison with the other antennas.

73,
John WA5MLF

Radio Propagation Issues for the RV Service Net

During several months of observing the Eastern/Central RV Service Net and providing remote station access to W4BXI, the ability of net participants to communicate was analyzed.

The results of our study are presented in this document (PDF), which is focused on the 40 m band propagation during the time frame of the morning net on 7191 kHz. Marginal radio propagation at the current low point in the Solar Cycle makes it difficult for net participants to hear each other.

Our presentation combines observations of signal levels, net participant reports, ionospheric "soundings" and propagation modeling.

John WA5MLF
Dan KC4GO

RV Service Net - 11 April 2019

During the second hour of Thursday's net I captured some audio and screen shots of the activity. The net control station, Sam WA4ICK, was S9+10 to me (in Baton Rouge) and painted a strong image on my FLEX-3000 SDR waterfall/panadapter view as shown below.

Click on image for an expanded view.

Improved propagation noted by several net participants can be attributed to an active region (with sunspots) on the Sun that has rotated back into Earth view and is raising the solar flux. On April 11 the sunspot number was 13.

A sample of the audio recording from around the middle of the second hour illustrates the reception here of signals from WA4ICK and W3TOM. Below is a screen shot of a portion of the audio waveform. You can see how the signal-to-noise (S/N) ratio changes after the hand-off from WA4ICK to W3TOM at about 1/3 of the way from the left.

Click on image for an expanded view.

The first third has a narrow baseline between syllables, indicative of my receive AGC turning down the gain in the presence of the strong signal. The remainder of the waveform has a lower S/N ratio as indicated by the thick baseline. Some fading is evident. The signal improved after the first few seconds. In this later 2/3 of the waveform the AGC opened up to allow more signal, but the noise was also higher. Click here for a 47-second recording that includes the portion represented by the above waveform.

 I have two longer recordings that I can share with interested parties upon request.

73,
John WA5MLF

RV Service Net Reception at WA5MLF

During the last half-hour of yesterday's RV Service Net the signal from W4UOA was solid at Baton Rouge. The distance from my station to W4UOA is 430 miles.

Below is a screen shot captured at 0751 CDT, while W4BXI was transmitting on 7191 kHz  from W4UOA. Another strong signal can be seen below 7188 kHz.

Click to enlarge view.

A little earlier (0728 CDT) I recorded KB0BH checking into the Net and acknowledged by W4BXI. The recording (click here) was made from my Flex-3000 transceiver in Baton Rouge.

73,
John WA5MLF

Open Wire and TPARCA

Click above to enlarge image.

Here's the cover of the March 1989 issue of Open Wire, the news bulletin of TPARCA. Note that the dial-up bulletin board system was in use at the time. For a bit of nostalgia you might like to listen to the sound of a dial-up modem connecting on this YouTube video. It offers explanations and waveform views of each stage of the connection process, starting with dial tone -- something that young folks rarely hear.













Among the contents of this issue was the following certificate from the ARRL:

   

The back page of the issue includes the Telephone Pioneers emblem:

N4AHJ has provided a large volume of historical Open Wire and TPARCA material that I can make available to any interested members.

73,

John WA5MLF