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Project Polyglot  -  26 October 2017 - Outside Antenna

The repeater has been using a 70cM Slim Jim antenna since the beginning  of this project.  The Slim Jim is suspended from the ceiling of the radio room by a short piece of monofilament fishing line.  The combination of 5 watts of transmitter power along with the Slim Jim antenna, provides up to 3 miles of coverage.  However the coverage is not consistent.

I have decided to try my hand at designing and building a collinear for the repeater and mount it outside at a height 25 feet.  The collinear will provde a more consistant coverage footprint.  First pass, will be to model a 3 element collinear and conduct trials to determine its  effectiveness.  If all goes well in the trails, I will then move on to designing 6 element version.  The collinear will be made out of 10 AWG wire and use a quater wave stub for matching.

By the end of this year, Project Polyglot will hav a permanet place in the radio room and I will be freed up to go after new projects.  I have developed an interest reflectors for the DV modes.  The new XLX Multi-Protocol and YSF reflectors are a special interest. 



Project Polyglot - 27 September 2017 - D-Star + DMR + Fusion/C4FM
Final digital voice mode added for this phase of the project - Fusion/C4FM.  Upgrade include the purchase of the Yaesu FT-2D HT. Adding Fusion to the Polyglot was the easiest of all the modes.  Figuring how to locate and connect to a room with acitivy was another matter all together.

Project Polyglot - 17 September 2017 - D-Star + DMR

Two major updates to the repeater this weekend.  First, I migrated to the Pi-Star image.  Second, I added enabled D-Star.  Finally, we have a mult-mode repeater.  I opted for Pi-Star because it allowed me to enable D-Star with very little effort and troubleshooting.  Once, I figured out how to program the IC-92AD (completely new to D-Star...knew less about the IC-92AD). Up on the air after an hour of work. Made a quick contact with a station out California.  Next Fusion.

Project Polyglot - 12 September 2017 - D-Star


Now, moving on with adding D-Star to the home brew repeater.  I was lucky enough to have a IC-92AD loaned to my for the cause.  Call sign successfully registered with the help a from a D-Star repeater owner.  After spending a few hours with the IC-AD's manual, I was convinced my santiy would be saved if I ordered the programming software from RT Systems as opposed to programming from the HT's keyboard.


On variable at a time.  Get the IC-92AD working with the local D-Star repeater and learn how to link/unlink from reflectors and any other standard practices expected of one transversing the D-Star universe.  Next, configure up the Polyglot to support D-Star.

Fusion is next.  Still mulling over the FT-70D vs. the FT-2D.

Project Polyglot - 12 July 2017

The duplexer for the repeater finally arrived and it works as advertised.  The duplexer is rated at 50 watts.  A quick test at the repeater's frequency pair. (441.375/446.375), the insertion loss was < 1 dB and the band reject filter provides -90 dB of antennuation.  Chinese makers have a bad reputation when it come to these types of products.  This product dismisses that reputation.

The RF interconnection cables are made by Tensolite and were purchased at Tanner's Electronics in Dallas, TX.  The cable assemblies are rated up to 16 GHz and orignally sold  by the vendor for $65 each.  I picked up 6 for $15 each.  Well worth the investment.

Next, an antenna for outside.  I haven't decide what type of antenna to build.  The requirement is an omnidirectional radiation pattern.  

Project Polyglot - 23 June 2017

The KA1GMN  repeater is now listed on  RFinder (RepeaterFinder) Worldwide Repeater Directory.  


I have added DMRGateway to the repeater system which enables to system to connect to muliple networks:

  Talk Group 6 - Experimental XLX reflector XLX950 - Modules A, E, F, G and I.


  Talk Group 8 - Phoenix UK and Europe DMR Network - Reflector 4409 AKA  CQ-UK WIRES X ON C4FM


  Talk Group 9 - The Brandmeister Network 

Project Polyglot - 16 May 2017

I configured up the Raspberry Pi with MMDVMHost and tweaked the MMDVM.ini conifiguration file as to have the system operate as a full duplex repeater.  MMDVMHost successfully logged in to the Brandmeister network.  I applied a few static talk groups in the repeater profile in Brandmeister.  When those static talk groups are active, traffic is being routed to MMDVMHost which, in turns, activates the PTT on the Nano MMDVM MODEM.  Just waiting for a few more parts for the Motorola CDM 1550s and we'll be ready to build.

Project Polyglot - Backyard Multi-Mode Digital Repeater - 15 May 2017


The goal is of this project is to build a Multi-Mode Digital Repeater which will support DMR, DStar, and Fusion.  This is a backyeard repeater project whose coverage will be limited to around 5 miles.  

Raspberry Pi 3 - MMDVMHost

Micro Node International (Teensey 3.6) MMDVM - Modem/interface to radios.

Motorola CDM-1550 UHF Tranceivers




Project Litter Ear - 10 April 2017


The beverage is installed.  I was only able to do 130 run along the back fence line.  I used 20 AWG telephone line with approx 1  to 2 turns per inch.  The beverage runs E-NE and S-SW.  The feed line to the shack is Belden 75 ohm coaxial pair.   For ground, I connected the KD9ZV transformers to the fence' s metal posts.  Observations so far:


40M - Notable inprovement. SNR values off the beverage is at least 2 dB better. over the 60M quad loop.  The beverage is hearing twice as many station over the loop.  I worked Japan and Australia this morning and the beverage had a 2 to 3 dB over the loop.

60M - The beverage is electical just over 1/2 wavelength.  Noise floor off the Beverage is 10 dB lower.  There wasn't enough DX stations on last night so I could do a good comparison.


Project Little Ear

The KD9SV Reverseable Beverage Antenna Kit was dropped off yesterday.  Included in the order, were two 75 ohm coaxial surge suppressors to keep from blowing up the front end.  Need 200 feet of twisted pair and two 3 to 4 foot ground rounds.

Project Little Ear - 1 April 2017

60 meters is a fun band, but I need to improve the SNR of stations coming out of Europe.  I have decided to give a 1 wavelength Beverage antenna for 60M.  The Beverage will also by used on 40, 30, and 20 meters.


Project 60 Meters

I have always been attracted to 60 meters.  This band sits right in between the 80 and 40 meter bands and inherits attributes from both bands.  For the winter season, I decided I would spend most of my station operating time on 60 meters.  There is DX on 60 meters.  The JT65A gang planted themselved on USA channel 3 (5357  KHz) for some time now and I wanted to join in the fun.  In the past I had operated on 60 meters with JT65A and a doublet.  I could easy work any sation within the contental states with 1 watt.

I tried an inverted V first.  The inverted V produced good results.  All of North America could be worked with 1 to 2 watts of transmitter power.  DX was a whole different ball game.  Signals out of Europe were either very weak (-26 dB) and the few contacts I was able to make with European operators produce same SNR levels.


A vertically polarized loop was selected and it has become my main antenna for 60 meters.

Project Echo - Nextion Display - 3 January 2017

The Nextion came in, along a TTL <> USB adapter.  Up and running in 15 minutes.  Eye candy.

Here's a video of the Echo with the Nextion display.  

Anyone played around with Zibee and a Raspberrt Pi 3B?  A 900 MHz mesh looking attractive.

Project Echo - New Image - 31 December 2016


Happy News Year's Eve Everyone!

Nextion display on order from Amazon.  The Raspian Jessie Lite on Echo is working without any issue.  The image uses only 3Gbytes of space of the microSD card.  

Project Echo - New Image - 29 December 2016


I have reach a point with the x-windows GUI has not purpose any more.  Downloaded Raspbain Jessie Lite.  No GUI - just the CLI. Echo moves toward being more of a wireless appliance.  Same issue with the Rasp Pi's Bluetooth conflict with the DVMEGA board.  I forsee 100 years from now, some poor sod still fighting with a port conflict.

    The Display

    One of the goals of this project was to provide some visual indication from Echo that it was alive and connected to the Brandmeister network.  The solution is a 2.5" Nextion display - interface to the Rasp Pi via a USB>TTL interface.  MMDVMHost supports this display, so after a few routing of wires and tweak of the code - Echo finaly has a face.  Currently, the Nextion display is on order.  Trips to the local sources in the Dallas Metro Area did were deviod of Nextion displays - bummer.  Well, you can't win them all.  


Project Echo - SMS Text Messaging - 21 December 2016

SMS messages is another feature of DMR and what  attracted to this mode in the first place.  Results to date, have been inconsistent.  Moving text messages between DMR radio by different vendors requires some flipping of levers and spining of knobs and even then, it seems to be inconsistent.

I teamed up with Ken, SM3VRO, today for a round of text messaging.  Ken used a TYT MD 380 and I was using my Tera 7400.  We both use the MMDVMHost on a Raspberry Pi with the DVMEGA board.  We are both jacked in to the Brandmeister network.   Initial SMS messages from Ken produced interesting results:

The problem was remdied when Ken changes is Brandmeist profile setting "Brand" from "Chinese", to "ESTI".

Project Echo - Coverage Test - 18 December 2016

I did another test of Echo's coverage.  This time, I hike to the West of my QTH.  There is a ridge, 1 mile away, which looks down in to the development I lived in.  A good place to do some radio checks.  At a range of 1 mile to the QTH and running 4 watts on the Tera 7400 HT, I was able to hit the HotSpot.  Radio checks on the Brandmeister Nationwide talk group stated my audio was clear with no noticeable packet loss.  


Project Echo - The DMR HotSpot - Echo Goes Wireless


I added a Cisco/Linksys USB Wi-Fi adapter to Echo.  While the Rasp Pi 3 does have an on board Wi-Fi radio, it is limited to 2.4 GHz.  The 5 GHz band is relatively clean in my neighborhood and you can still find a clear channel - especially true on the UNII-3 band.


I need the wireless connect to three different SSIDs - 1 each for home , office and mobile.  This requirement was met by changing the contents of wpa_supplicant.conf.  One network entry for each SSID. Priorities were assigned to each SSID.  This ensures Echo will stay attached to the home Wi-Fi system and the the T-Mobile HotSpot when it activated.

Applications requiring low delay and packet loss, like voice, is a challenge across any wireless media.  An effective QoS policy is paramount.  Really, that goes for any time sensitive traffic - even interactive application like SSH.  To ensure SSH traffic is marked to indicate to the in and outbound queues on Echo, here's my first attempt:

# Marks in/out bound SSH traffic in IP Type of Service (TOS) - low delay

sudo iptables -t mangle -A PREROUTING -p tcp --sport ssh -j TOS --set-tos Minimize-Delay
sudo iptables -t mangle -A PREROUTING -p tcp --dport ssh -j TOS --set-tos Minimize-Delay


# Verification

 sudo iptables -L -t mangle -n -v


# Results

Chain PREROUTING (policy ACCEPT 185K packets, 17M bytes)
 pkts bytes target     prot opt in     out     source               destination
    0     0 TOS        tcp  --  *      *              tcp spt:22 TOS set 0x10/0x3f
2663  128K TOS        tcp  --  *      *              tcp dpt:22 TOS set 0x10/0x3f



After applying this policy to Echo,  the delay I was encountering during a SSH session, has almost virtually dissappeared. 

I am reading up tc an iptables, so as to build classification and marking policy for the voice traffic to and from Brandmeister.





I have been a ham since 1981.  I got my technican ticket at the FCC field office in Boston, MA with my father, Clarence Williams, W1ROM - an avid 80 meter DX chaser in his time.

I did a career in the United States Air Force (21+ years) and most of it was spent in the Electronic Warfare field.  Now, instead of jamming emitters,  I help build them.  A Wi-Fi engineer of sort for the last 10 years - working for a large cellular carrier.


For the past 10 years, we have been living in Euless, Texas.  Most of that time was spent on HF operating a myriad of digital modes with a lean towards JT65A and JT9.  These weak signal modes will always amaze me in what they can do with just a couple of watts of RF power applied to an odd bit of wire in the back yard.   HF activities have been put aside in the past two years as other things required my attention.

Current interest is DMR and it global reach on the planet.  On a whim, I picked up a Tera 7400 DMR HT from Ham Radio Outlet in Plano, TX.  I spent the next few days learning about things like talk groups and code plugs.  I do not have a D-Star or Fusion background, I jumped feet first.  Next thing was a project to build up a DMR HotSpot.  I was intrique by what a Raspberry Pi 3 could do - a simplex repeater which connected to the Internet and the world.  I could not leave well enough along with the HotSpot.  I chucked its "stub" antenna and made a Slim Jim antenna with the goal of improving coverage in to the park next to me.  Best distance - .85 miles so far and the operators work reported that my audio was fine.  Amazing what a 10mW HotSpot will do given a respectable antenna is attached.

Now, I am trying to working out text messaging via DMR.  The results vary and I find it interesting to figure would what the root cause of the problem is.  The fact that DMR is not perfect make it all the more interesting and inspires me to experiment.


Project Echo - The DMR HotSpot


The Echo project is my initial journey in to the wide world of Digital Mobile Radio (DMR).   I had become bored with radio over the past year.  However, in November 2016,  I purchased a DMR HT - the Tera 7400 from Ham Radio Outlet in Plano, Texas. 

Without any background in any of the other digital voice technologies, I jumped in - feet first, in the wide world of DMR.  Next came a DMR HotSpot as I was intrigued with the concept of having a UHF simplex repeater which would provide not only good coverage around the home QTH, but also coverage in to a city park located across the street from our house.  Thus began The Echo Project.


Echo 1 - 1st DMR HotSpot


The DMR HotSpot I threw together consisted of:

         1 Each - Raspberry Pi 3


1 Each - DV MEGA VHF/UHF Radio Board

1 Each - Homebrewed Slim Jim 70cM Antenna (made out of 450 ohm window line)


1 Each Cisco USB Wi-Fi Interface Adapter

1 Each 20 Amp/Hour Sealed Lead Acid Battery (SLAB)

1 Each Powerwerx Power Meter and Analyzer

Operating System: Raspbian/Linux 8

HotSpot: MMDVMHost by Jonathan Naylor, G4KLX - https://github.com/g4klx/MMDVMHost

   Version: 20161021 

RX Frequency: 446075000Hz
TX Frequency: 446075000Hz

Transmitter Power: 5 mW

Antenna: 70 cM  Slim Jim (450 Ohm Window Line)


8412419 Last modified: 2017-10-26 17:08:47, 26753 bytes

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QRZ Logbook Summary for - KA1GMN
Latest Contacts for KA1GMN at QRZ.com
dedateband mode grid Country op
OE3BUB 2013-12-17 40m JT65 JN88fg Austria Bernhard Buchta
W9MDB 2013-12-13 40m JT65 EM49HV United States Michael D Black
N9OJC 2013-12-06 40m JT65 EN60tr United States JOHN E TIMMONS
N9DUG 2013-12-06 40m JT65 EL87 United States DOUGLAS H HERROLD
N8ESP 2013-12-01 20m THOR EN80ld United States JOHN C GARCIA
AK4BB 2013-12-01 20m JT9 EM83cl United States GEORGE D WALDROP
KD8GNC 2013-11-30 20m HELL EN80lc United States Tery
KI6WJP 2013-11-29 20m JT9 CN81uh United States Martin J Nile
W9SMR 2013-11-28 17m PSK31 EL87sf United States STANLEY M ROBINSON
K4PYR 2013-11-28 30m JT65 FM17rd United States ERIC R WOOSTER
KR4IP 2013-11-20 15m JT65 EM83bm United States RICHARD K STUDDARD
N6SBN 2013-11-17 20m PSK63F CM96ax United States CRAIG A HARLAMOFF
KT4DLB 2013-11-17 20m PSK31 EM61sh United States Danny L Brown
K8JTD 2013-11-17 40M JT65 EM79wo United States JEFFREY T DEVOE
K3FS 2013-11-17 40m JT65 EN90xj United States Franklin S Speicher, IV

Book Totals: 476 qso's   458 confirmed Get a free logbook at QRZ.COM

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