May 2020 Tech TalkMay 2020 Tech Talk

Mingus Repeater Site Review & Mingus Repeater Site Review & Introduction to AllstarIntroduction to Allstar

bybyDoug - NO1DDoug - NO1D

Tonight’s AgendaTonight’s Agenda● Overview of equipment installed at the site● 2019 and 2020 Projects completed● Challenges – High RF fields, desense issue from YCSO

● 2m and 70cm Repeater Status● 2020 Projects being planned● Linking – What is Allstar all about

What equipment is installed @ MingusWhat equipment is installed @ Mingus

● 2m Repeater● 70cm Repeater● APRS digipeater● 70cm Control● 220 Mhz Repeater● WinLink Digipeater – offline 5/16● MARS Repeater – offline 4/20● Various controllers, power supplies,

cellular router and networking

Tower ViewsTower Views

2019 Quick Review2019 Quick Review● New crystals for Daniels MT2 Rx/Tx

● Replaced Yaesu VX7k with Daniels

● 2m Site Survey, performance measurements

● Repair of VHF Amplifier(s)

● Refurbish of Link Systems RLC4 controllers

● Deployment of Cell Router, Allstar controller, new controller interfaces

● Solid State Relays for remote control ops

● Replacing defective APRS radio

● Tests with new Filters

● Linking 2m, 70cm & Allstar● Creating W7EI Hub Node (more

later)● Procurement of many spare modules● Hut Cleanup, Fan/Cooling, Temp

Sensor● Grounding improvement● Tower work including 70cm antenna,

2m antenna

Why Swap to a DanielsWhy Swap to a Daniels● Better front end selectivity for

improved Rx performance● Chassis based, ease of module

replacement to reduce downtime● Higher MTBF – fewer parts● Lower power consumption● Two chassis from Squaw we could

re-use● Simplier, cleaner interface w/

controllers which we had for remote control

Daniels RxDaniels Rx● Dual Helical BPF in

front end w/ LNA● 2nd IF Helical Filter● TCXO version here

Daniels TxDaniels Tx● TCXO version● 4W out max● Helical Filter

Daniels AmplifierDaniels Amplifier

● Takes up dual slot in backplane● Wideband simple design; tunes

in Ham Band● Thermal controlled● 30W out, 4W in● This is early design VT2,

currently running VT3 module

Crystals & SynthesizersCrystals & Synthesizers

You’ve heard of You’ve heard of Bugs in HW?Bugs in HW?

High RF Fields !High RF Fields !

The YCSO Desense ProblemThe YCSO Desense Problem● Very High RF Field Site

– You see 0dBm (1mW) sigs at Antenna feedlines on VHF !

● YCSO 120ft away● NOAA Wx 120ft away

– 24x7x365 transmissions

● MMRG 100ft away● Airband 120Mhz thru 138Mhz● Several VHF Ham Repeaters on Mt.● DTV at 170Mhz● High Noise Floor

● Random desense● YCSO has to be transmitting● Weak signals primarily

affected– Occasionally hits strong

signals into Rx

● Zero desense w/ antenna disconnected

Many Attempts Many Attempts were madewere made

● Terminated all unused feedlines/antennas

● Improved Grounding● Measured Duplexer again● Tried Several BPF designs on Rx

– Home Brew, 800Kc, 400Kc– Measured 1dB Blocking Range on Rx;

about 130Kc

● Installed OCI 2m BPF on antenna; brute force !

● Incremental improvements, however problem persisted

Identified… we believeIdentified… we believe● Terminated MARS feedline, desense

problem went away● Isolated intermittent and oxidized

feedline; duplexer to bulkhead● Desense did not require MARS

repeater to Tx ! ● Suspect IMD generated from high

RF hitting PA– No circulator/isolator in Tx path– Mobile duplexer, poor rejection

● MARS team is looking to upgrade their equipment

A Detailed Site Survey looking for IMD productsA Detailed Site Survey looking for IMD productsIs high priority. We need to get to root-cause!!Is high priority. We need to get to root-cause!!

Current 2m/70cm Repeater Current 2m/70cm Repeater StatusStatus

2m2m● Audio bit low; adjust● Address squelch tail noise;

Rx open on release of PTT● Unique tone from 70cm● Add back BPF/LNA to Rx

path for increased Rx performance

70cm70cm● Duplexer found intermittent● Currently 17W; increase to

25W - 30W● Audio level adjustment(s)● Replaced Lightning Protection● Control Channel work● Add BPF/LNA to Rx path

2020 Projects2020 Projects● Hut Painting and Sealing

– Before Monsoon Rains !

● IMD Site Survey Report● 220Mhz Allstar Controller● Centralized Power supply

– Rework old breaker panels

● Add site Wx station● WinLink (under review)

● Removal old unused antennas off tower

● Grounding Measurements and Improvements

● Possibly Diplex APRS w/ 70cm for vertical separation

● Re-aim Control Channel yagi

LinkingLinking● Today’s Capabilities

– 2m and 70cm (no Allstar)– 2m w/ Allstar– 70cm w/ Allstar– 2m & 70cm w/ Allstar

● Two RLC4 controllers provide powerful audio switching matrix for linking

● Many points of audio adjustments :-(

So What’s AllstarSo What’s Allstar● Voice Over IP (VOIP)● Network of Repeaters,

Base Stations, Radio-less nodes & Hubs

● Based on OpenSource Asterix PBX software

● Supports EchoLink

● Can replace legacy repeater controllers

● Interfaces to variety of radios/repeaters– Many many models

● Great for Linking repeaters● Runs on variety of HW; rPI

series my favorite

Hardware ExamplesHardware Examples

Links Links mademade

Management Management InterfacesInterfaces

Management InfoManagement Info● Daily emails me a

connection log– Tracks node ID and IP

● Immediate notification if tunnel is lost

● SSH up to site allowing access to RLC controllers

Current Linking PolicyCurrent Linking Policy● Anyone can connect to W7EI Hub

(46005)● No inbound connections to node at

site (49941)● Can create white/black lists for

connection policy (not currently used)● Tech Committee member must

configure audio mux on RLC controllers– 70cm typically patched to Allstar

● Let us know if you want a link connection made

● 60’s Net – 2m ● TGIF Net – 70cm

● Note: EEE During emergencies may link 70cm (2m) to another machine to expand coverage area and support EM comms

Want to build a node ?Want to build a node ?● RPI3B+, good 5v supply● DMK Engineering URIx

– USB cable from rPI to URIx

● HamVoip Software Distro– 8G Micro SD card

● Home Brew Cable– DB25 to Radio– Tx, Rx audio– COS– PTT

● Can use almost anything for radio– Even Baofeng series

● Can work over WiFi– I like Ethernet however

● Register with AllStarLink.org for node number

● HamVOIP vs. ASL– Registration differences

● Contact me if you have questions

VVARA Allstar FuturesVVARA Allstar Futures● Possibly replace old RLC

controllers and go direct to Allstar– Eases automation of linking– Direct control over audio

levels– Voice ID – Special Announcements

including Wx/Fire alerts ?

● Add in 220 machine for Rodney KI6FH– More linking

possibilities

ThanksThanks● Thank you for your patience while we maintain club

machines and continue to improve performance at our site(s).

● Email: no1d.doug@gmail.com● Tel: (978) 602-5487 (emergencies please)