VHF Propagation


VHF Propagation 

 Do you want to know if the VHF bands are open?  Take a look at this hourly updated map to find out. 
 
http://aprs.mennolink.org/ 

This map shows actual radio propagation from stations operated near 144 MHz. It uses data gathered by Automatic Packet Reporting System-Internet Service (APRS-IS) from packet stations in the amateur radio service. 

The map shows activity that has happened in the past hour. Paths are combined to create color-coded footprint indicating the distance VHF signals are likely to be traveling. Packet stations typically run low power into small vertical antennas. Better equipped stations should exceed the the distances these stations report.

The map is updated automatically, typically several times per minute. The map is created using positions (latitude and longitude) reported by nodes in the packet radio system and the hops from node to node that the data travels. By correlating the hops with the position of each end of the hop, the distance can be inferred.  

 

Interested in 50 MHz and above?


For those of you interested in 50mhz and above…..
Archive of several dozen technical presentations is available on the 50 MHz and Up Group for your stay-at-home reading pleasure.  It is at http://50mhzandup.org/archive.html and includes info on our 10 GHz linear translator, talks on building 10 thru 122 GHz radios, IF SDRs, EME rover stressed dishes, waveguide transitions and feeds and more.
122ghz ?? Really??
Enjoy,
Jerry N3RBW

RT #200 SPECIAL EVENT


200th session of the RT

SPECIAL EVENT THE 200th Session of the RT!
Join Joe, W3GMS, as he hosts the Thursday Night RT on 146.985,
Thursday @ 830 pm Eastern Time.
Check out the new forum https://w3gmsrepeater.forumotion.com
146.985- MHz;
TX PL 100.0
RX PL 94.8 (RX PL is NOT required, Optional)
Technical questions can be asked during the RT.  If the answers require a more in depth, one on one discussion, a session can be done after the RT or scheduled for another time.
Looking for Hosts to host future sessions.
You are invited to join us in the best weekly rag chew in the area:
      The 985 Round Table… Thursdays at 8:30 p.m.
   on the W3GMS repeater  —
The repeater website is www.w3gmsrepeater.com
New to the roundtable?  Checking-in late?  Can’t stay very long?
That’s fine; check-in anyway!  You are always welcome…
and the roundtable often lasts until about 10:00.
–  –  –
To avoid the first syllable of your transmission being cut off, wait one second before talking.  Click, Wait, Talk.
Willing to serve as a roundtable host from time to time?  Feel free to contact Jim, AF3Z – jagoudie@comcast.net, or Phil, KC3CIB – kc3cib@gmail.com for helpful information and to discuss scheduling
Don’t let yourself be cut off!  There is a 3-minute timer on the repeater and it will cut you off if you talk too long.  Never fear.  You can reset it very easily; simply let up on press-to-talk button for a moment.  There’s no need to wait for the repeater carrier drop.

LATEST NEWS FOR 985


DUE TO COVID-19 RELATED RESTRICTIONS, THE MONTHLY BREAKFAST HAS BEEN CANCELLED UNTIL FURTHER NOTICE.

Join Joe, W3GMS AS HE HOSTS A VIRTUAL 985 BREAKFAST ON THE REPEATER ON THE 3rd FRIDAY OF THE MONTH AT 9AM.  Bring your cup of coffee and your breakfast and join in on the Virtual Breakfast! The next one will be June 19, 2020

THE CDC and Governor Wolf, has recommended that everyone wear a mask when out in public.

EMCOMM, EMergency COMMunications.

In case of the repeater being off air, the emcomm protocol for 985 will be using 146.985 Mhz SIMPLEX.  It is suggested that you program a “memory channel” for 146.985 simplex, NO PL Tone, 0.000 Mhz offset (may have to change the auto repeater offset to 0.000 Mhz).  

We have done a couple exercises on the repeater and on 75M.  We will be trying some other frequencies in the future, if there is enough interest.

Cheap Portable Multi-band Antenna by K3DZM


Article submitted by K3DZM

While pondering a portable antenna the other night, I decided I wanted to build such a beast with parts that were staring me in the face!  It was partly an antenna in theory with material creativity mixed in.  The antenna was not designed to be a permanent outside antenna, since the materials in my apartment were not designed for that.

Many new hams have limited space and/or are afraid to DIY an antenna for HF.  Those that rent have limited space so, with that in mind, I wanted to make this a small footprint antenna.  Plus, from my previous statement, I wanted to use the materials that were staring me in the face!

For folks that have limited space and possibly a picky XYL who does not want some large monstrosity  of an antenna or big tower sticking up in the yard, this multi-band antenna may be just what they are looking for.  Well, to those people I say don’t panic, at least not yet.  Being a relatively new Ham, my junk box is rather limited, but even with that restriction, I found a way of using some parts I had around the shack along with some ingenuity to build this multi-band antenna fed with open wire line.

With an open wire line fed antenna, the antenna does not need to be resonant, unlike a coax-fed dipole.  Typically the antenna performs well when it is close to a ½ wavelength total length at the lowest frequency band of operation.  As you go higher in frequency the antenna exhibits gain at the expense of directivity.  With low dipoles, the directivity is not an issue. With any open wire line fed dipole, you will need a balanced antenna tuner to match it to the 50 ohm output of one’s transceiver.

This antenna was made with 12AWG wire, 6 BIC pens, a bag of zip ties, a plastic hanger and some wire cutters.  Each leg of the antenna is about 25’, give or take 3 feet. The center insulator was made from a coat hanger that was modified.  The antenna is fed with about 12’ of balanced ladder line. The ladder line was made with the same 12AWG wire as the dipole.  For spacers I cut the BIC pens into about 1.5 in pieces after removing the ink and tips.

Zip ties hold the wires to the spacers.  The feed line is soldered to the dipole with heat shrink for protection.  With the quick use of a lighter, in a well vented area, I was able to melt the hanger back onto the piece used for the center insulator.  This allows the antenna to be hung on branches, rope, or anything you can get the hanger around.  For the end insulators I used yellow clips I got from my work designed to hold gloves.  They are strong and the wire can be wrapped around these to affix to any anchor points.  Rope may be attached to the end points for getting the antenna up higher in the air.  Any plastic clip or specific insulator will work as long as the dye used in the plastic is non-conductive at RF frequencies.

So how did the antenna match up?  Being close to ½ wavelength on 40 meters, the performance of the antenna will be reasonable on 40 meters.  Going higher in frequency, the antenna performance becomes very efficient.
Cheap Portable Multi-band Antenna Annota10

Even though the antenna shows a low SWR on 80 and 160 meters, the antenna performance will be very low on those bands due to the very short electrical length of the radiating element.

Operating frequencies in red are not suggested to be used with this antenna as its currently designed.

All testing was done with the MFJ 962D and Icom IC-720. My IC-720 does not do six meters so I was unable to test that band. The frequencies used were selected due to the limitations of my General ClassLicense. The two bands that I consider not usable are 80M and 160 meters based on its electrical length and not the SWR values.  The Antenna was placed on a 13ft aluminum light pole.  Try to keep the open wire line from any metal objects.  The dipole legs were also only about 6-10 feet off the ground.  So for the cost of a family trip to McDonald’s you can have a small, portable multi-band antenna for 40M thru 10M.

Cost Breakdown
Source of parts – Amazon
12AWG solid core wire in black can be bought in a 100ft roll for $19.59  https://www.amazon.com/dp/B00FY51XGQ/ref=cm_sw_r_other_apa_i_.BPBEb6EG5XW5
A 50 pack of the pens can be found for $6.33 https://www.amazon.com/dp/B00CLHE47A/ref=cm_sw_r_other_apa_i_QEPBEbK18RWPP

I’m going to assume you have wire cutters, a lighter, plastic hanger. This makes the total cost at the time of writing to $25.92

Now you don’t have an excuse not to get on the bands and operate!

73 till next time,
Dylan – K3DZM
\Cheap Portable Multi-band Antenna 20200310
Cheap Portable Multi-band Antenna 20200312
Cheap Portable Multi-band Antenna 20200311
Cheap Portable Multi-band Antenna 20200313
Cheap Portable Multi-band Antenna 20200314
Cheap Portable Multi-band Antenna Screen10

RST Reports and How To Give Them


RST REPORTS AND HOW TO GIVE THEM

This guide is for HF.  For giving signal reports on a repeater see: Giving Signal Reports when going thru a Repeater

What Does RST mean?

How do I give a proper RST report?

The acronym RST stands for: Readability – Signal Strength – Tone

If you’re operating phone or voice, you’ll give just the first two, the R and the S.

If you’re on HF you may hear: “You’re 59” or “You’re 5 by 9”

The first number, “five” is a measurement of Readability. Are they intelligible? It’s how clear their or your voice is. This can be confusing.  A completely clear transmission doesn’t have to be strong at the same time. The incoming transmission could be very weak, but you can understand each word said – as if someone’s whispering in your ear. That’s why the operator would deserve a 5 on the Readability scale.

The second number “nine” is a measurement of the Strength of your voice to the other operator. A nine, the highest value, would mean your voice was as strong as if you were in the same room with him and talking at a normal volume.

Most ham transceivers will have a signal strength meter. They can help you with the S component of the report.

When you decide to do Morse code, you add another component – Tone.

Now this is the harder one to give. Two people listening in your operating shack might perceive the Tone differently.

Try and give a realistic signal report. Most operators want the truth and they want to know how band conditions are between your station and their location.

Now here is the “kicker”.  In contesting, signal reports are generally all “59(9)”.  No matter how weak or strong yours or their signal is you get or give a “59”!  I have personally had to phonetically repeat my call sign multiple times, and was still given the perfect “59”.

 

R: Readability

1 — Unreadable

2 — Barely readable, occasional words distinguishable

3 — Readable with considerable difficulty

4 — Readable with practically no difficulty

5 — Perfectly readable

 

S: Signal Strength

1 — Faint signals, barely perceptible

2 — Very weak signals

3 — Weak signals

4 — Fair signals

5 — Fairly good signals

6 — Good signals

7 — Moderately strong signals

8 — Strong signals

9 — Extremely strong signals

 

T: Tone

1 — Sixty cycle A.C. or less, very rough and broad

2 — Very rough A.C., very harsh and broad

3 — Rough A.C. tone, rectified but not filtered

4 — Rough note, some trace of filtering

5 — Filtered rectified a.c. but strongly ripple-modulated

6 — Filtered tone, definite trace of ripple modulation

7 — Near pure tone, trace of ripple modulation

8 — Near perfect tone, slight trace of modulation

9 — Perfect tone, no trace of ripple or modulation of any kind

Why Open Wire Fed Dipoles Need To Be Balanced


It is important, if you’re using a dipole antenna fed with open wire line feeders, to try and keep the antenna balanced. The first rule is to make sure both sides of the antenna are the same physical length. Sometimes, even when doing that, the antenna will not be balanced due to the asymmetrical issue. If one end of the antenna is not the same distance above ground as the opposite side, that may cause an electrical imbalance. Objects that are close to the antenna can cause some imbalance. Some of this we have control of and some of these physical issues causing an imbalance we have no control over. First off, make sure you have the same amount of wire each side of the center insulator.

In a well designed open wire line fed antenna that is balanced, the feedline will not radiate! The open wire line feedline, should not radiate! When the antenna is balanced, the current in each leg of the feedline will be equal, but 180 degrees out of phase. It’s the equal amplitude and 180 degrees out of phase that keeps the feedline from radiating. Feedline radiation in or near the shack can cause all sorts of issues, including RF in the audio of your HF rig. In a smaller way, it will cause the radiation pattern of the antenna to deviate from the text book model due to feedline radiation, although, that in my eyes is no big deal.

Giving Signal Reports when going thru a Repeater


 Tech Tip #1 Giving signal reports when going through a repeater

Post by W3GMS on Sun 16 Feb 2020 – 13:22

Keep in mind, when your working a station on the repeater and he is changing his output power, giving an “S” meter report really does nothing. Your “S” meter is listening to the repeater and due to that, when a user changes power, you will not see any difference since you receiving the output of the repeater whose power remains constant. The best you can do, is listen to the signal to noise ratio and tell him when noise starts encroaching on his signal as the repeater hears him.

S meter reports remain useful when your working stations on simplex and not going through the repeater.