Thursday, January 27, 2011

January VHF Contest - Mt Diablo



The ARRL January VHF Contest was the weekend of Jan 22-23 this year. Last year I operated from Mt Vaca (CM88), but this year I decided to operate QRP in the "Single Operator Portable" category from the summit of Mt Diablo (CM97). Mount Diablo is a 3950' peak situated roughly in the middle of California's central valley, with line-of-sight views for hundreds of miles in many directions. Rather than hiking, I took the easy way and drove to the summit, and used the truck's Yaesu FT-857D radio with power output turned down to contest QRP levels (10 W).



For antennas, I used the Elk dual-band log periodic array for VHF and UHF, and I used the truck's screwdriver antenna for 6 meters. Things worked out well -- in 3 hours I was able to make 78 QSO's over 9 grid squares in three bands. Weather conditions were perfect -- temperature around 60F, with sunny skies and calm winds.

Sunday, January 9, 2011

Home Satellite Station!



This weekend I replaced the 4-element Arrow VHF beam antenna with a 7-element M-Squared 2M7 VHF beam. The main reason for this was because the Arrow wasn't weatherproof, and I had to get it out of the rain before it corroded. A secondary reason was that the M-Squared antenna has quite a bit more gain than the Arrow -- I've found that this really helps pull the sometimes weak VHF-downlink signals out of the VO-52 and AO-07 sats. Here are some photos of the new installation: The twin Yaesu FT-817ND tranceivers and the Amsat LVB Tracker. The tracker is on left with the green display. The FT-817ND on the bottom with the orange display is used for VHF and is connected to the VHF yagi, while the FT-817ND on the top with the blue display is used for UHF and is connected to the UHF yagi:



This is the Yaesu G-5500 rotator controller. It's directly controlled by the LVB Tracker, and it connects directly wtih the rotators:



The cable feedthrough allows the two rotator cables and two antenna feedlines directly through the office wall. I wanted to keep the cable run as short as possible, so this hole is right beneath the radios. It isn't pretty but it's functional:



The antenna feedlines go to the preamplifier box mounted on the antenna tripod mast:



The preamp box houses the Advanced Receiver Research (ARR) pre-amps. One for 70cm and one for 2m. Both are switchable from inside the office:



Here's a view looking down (up?!) the two antennas. The M2 2M7 VHF antenna is on the left, and the 15-element Diamond yagi is on the right:



And here's the whole assembly:



And in this photo, the proximity of nearby houses is visible. Houses limit the visibility of the antenna to around 15 degrees to the south and 23 degrees to the north.



Finally, here's a short video of the antenna rotation in action:
video

Here's a list of the station components:

Support Mast:
10' steel pipe 1 1/2" diameter
Older style Radio Shack TV Antenna Tripod
Redwood 2x4 and concrete pier base

Rotator:
Yaesu G5500

PreampS:
Advanced Receiver Research SP432VDG - N connectors
Advanced Receiver Research SP144VDG - BNC connectors (not in use)

Antennas:
UHF Ant: Diamond A430S15 15-element yagi, mounted horizontally.
VHF Ant: M2 2M7 7-element yagi, mounted vertically.

Preamp Box:
Weatherproof camera box mounted to TV-mast support x 2.

Coaxial Cable:
VHF Feed (shack to box): 30' Tandy RG-8/U, PL-259x2
UHF Feed (shack to box): 30' Times Microwave LMR-400, PL259 + N connector
VHF Feed (box to ant): 8' Tandy RG-8/U, PL-259x2
UHF Feed (box to ant): 8' Times Microwave LMR-400, PL259 + N connector

Rotator Cable:
Rotator: Wireman 302 (2x40)':2-16, 6-18 Premium rotor cable, PE jacket
Rotator: Wireman 352 (2): 8 pole molded connector, male and female set.
(Molded connectors attached to controller end of cable)
(PowerPole connectors attached to 16-gauge lines to provide power to preamp box)

Rado Interface:
Yaesu CT-62 serial:CAT x 2
Serial-USB Adapters x 2 (FTDI chipset)

Rotator Interface:
LVB Tracker from AMSAT

Software:
SatPC32
Computer OS: Windows 7 - 64-bit

Radios:
2 x Yaesu FT-817ND

Monday, January 3, 2011

Satellite Antennas, Continued!



I spent part of the New Year's weekend moving the satellite array from the testing location (next to my garage, between two houses) to it's more-or-less final location in the backard (now between four houses!).



The new location gives a little more view of the sky -- it's pretty clear to the east and west (views down to about 10 degrees), and is limited by my own house to the south (about 18 degrees) and a towering 2-story neighbor's house to the north (about 23 degrees).

The antennas are the same as I used during testing -- a 4-element Arrow for the VHF side, and a 15-element Diamond for the UHF side. Both antennas feed to ARR pre-amps mounted on the mast; I keep the UHF pre-amp powered on all the time, but only intermittently use the VHF pre-amp since there is so much VHF noise in the local area.

The platform that the antenna sits on is built from 2x4 redwood and concrete block pylons. Pictures below!




I also modified the Yaesu G-5500 rotator controller to improve its accuracy. I had found that the controller sometimes had a drift or error of around 10 degrees, and searches on the internet indicated a cause of this problem could be the 7806 voltage regulator inside becoming unstable and oscillating. I checked out my regulator with an oscilloscope, and found that it was indeed oscillating by up to 100 mV at around 5 MHz. To solve this, I added a 0.1 uF tantalum capacitor directly to the bypass capacitor (0.01 uF) that's installed on the regulator output. This removed the oscillation, and now the rotator controller's accuracy is dead-on.

Saturday, January 1, 2011

California Lost Coast (CM79/CM89/CN70/CN80) Expedition

Dates: August 6-9 2011
QRV: Aug 7-8 2011
Modes: Satellite (+?)



Plans
Plans are coming together for a satellite mini grid-expedition in early August this year. The location will be the rare grid square CM79, along with the adjoining CM89/CN70/CN80 grid squares. I plan to camp out near Shelter Cove on the remote northern California Lost Coast area, arriving on Saturday August 6th. As weather conditions permit, I hope to operate as much as possible on the 7th and the 8th, and will return on the 9th. I'll work both linear and FM satellites: AO-51, SO-50, SO-67 (if on), ARISSAT-1, AO-27, VO-52, FO-29, and AO-07.

Location
Grid square CM79 is almost all ocean, with a small portion of the northeast grid corner extending up into the rugged California Coast Range. The actual grid boundary is reportedly 70 feet down a steep hillside from a ridge on Chemise Mountain. Looking at photos on the Confluence.org site, it seems the exact grid intersection is in a grove of oak and manzanita, and is already marked with a yellow box used by GeoCachers (http://confluence.org/confluence.php?visitid=2928). There's a hiking / pack trail that extends from a nearby campground, up about 1.5 miles to the ridge. If all goes well, I'll hike the trail with the portable satellite gear, and set up the station at the grid intersection.



Equipment
The equipment I'll use will be the same setup that I used on the previous Death Valley and Eagle Lake expeditions. This setup consists of twin Yaesu FT-817ND radios, an Elk antenna, a netbook computer for tuning and tracking, and PowerFilm solar panels.

Technicalities
The ARRL VUCC requirements indicate that "... the total area occupied by the station's physical setup, including operating position(s), power source(s), and antenna(s), must occupy some portion of each of the two/four grid squares simultaneously.". In order to achieve this, a combination of a centralized station (directly over the grid intersection) and a decentralized station (still directly over the grid intersection but with antenna located on the ridge) will be used depending on the particular satellite pass. This has been discussed with ARRL HQ and the plan has been confirmed as acceptable for VUCC credit:

Overhead and Westerly satellite passes:
Full station set up directly over grid square intersection. Specifically, I'll use the standard setup that I have used before, consisting of two Yaesu FT-817ND radios hanging from a photographic tripod, with the 6.4Ah LiFeP04 battery right next to the tripod. The antenna is an Elk antenna on top of the tripod. The area of the grid intersection will be marked with a ground tarp, and will be determined with better than 20' accuracy with WAAS-GPS. Photo and video will be used to document the station, GPS receiver, and surroundings.

Easterly satellite passes:
Since the view to the east is blocked by a ridge, 70' uphill, for easterly passes I will use the exact same station as above, except that the Elk antenna will be relocated to a second photographic tripod perched on the ridge. The Elk will be connected via 100 feet of LMR-400 coax, and I will use a preamp at the antenna to help overcome the signal loss on the 70cm downlink. As above, all station operation will be from directly over the grid intersection, including tuning, transceivers, and power source. The Elk can be re-aimed once or twice through the satellite pass to more or less keep up with the sat as it moves.

The disadvantage of the remote antenna setup is that it's using the single 100' LMR-400 coaxial cable for both transmit and receive. As such, the antenna-mounted preamplifier will switch off during transmit, so I'll effectively be operating half-duplex while on the V/U birds during lower easterly passes. Of course, the big advantage of the remote antenna + preamp is that it allows operation on easterly satellite passes without compromising the integrity of the station physically located on the grid square boundaries. Thanks to ARRL HQ Awards Branch for their suggestions and review of this plan.

Non-Satellite Modes
The primary goal of this expedition is to provide satellite contacts for people wishing to log the rare grid squares in this area. That being said, I will have the 2m/70cm antenna with me, so I may try some terrestrial SSB contacts. The weekend of the 6th/7th is the ARRL UHF contest, so if I hear anyone on 432.100 SSB, I'll try to contact them (remember I'm only running 5 watts QRP!). I also might bring the 6m HO Loop antenna for 6-meter sideband, but it's unlikely there will be any Es openings on 6 this late in the season. Since satellite operation is primary, operating on secondary modes will mainly depend on power budget (sunny = lots of power -- foggy or cloudy = will have to be careful).

Real-time GPS Tracking
I'll have my SPOT statellite tracker with me, and it will give the actual location of my position in real-time. Checking the SPOT page below will be the best indication of whether I'm at the operating position or not.
http://share.findmespot.com/shared/faces/viewspots.jsp?glId=07htI1NLFXRPkuxjfKceuGRTSqpQncKQ2



Pass Predictions
The following table shows the passes that I hope to be able to work. I'll work the linear satellites in the mid-to-upper end of the passband in SSB. Oscar 7 mode A is unlikely, but I may give it a try with a wire antenna for the downlink. I'll try to get on ARISSat-1 if it's available, and will cross my fingers that AO-51 is up and running as well. Due to the nature of the CM79 area (remote!!!) I won't be operating after dark, so the following table shows the daylight passes on local Sunday and Monday:



Checklist
The following is a rough checklist of the main items that I'll be bringing to the operating position. The system will be the same full-duplex portable satellite station that I have used in prior expeditions. In case the netbook computer that provides satellite tracking and doppler control goes down, I'll bring a backup frequency chart and pass prediction tables.

==== Radio =========
[] Yaesu FT-817ND x 2
[] Sat cable harness incl. diplexer
[] 6' RG-8x cable with PL-259's
[] 100' LMR-400 cable with PL-259's
[] Advanced Receiver SP432VDG low-noise preamp
[] Tripod x 2
[] Elk 2m/440 antenna
[] Netbook with SatPC32 and updated Keps
[] Boom mic headset

==== Power =========
[] 12.8V 6.4-Ah LiFePO4 battery
[] Solar Panels (60 watts total)
[] Charge Controller
[] Powerpole 4-way adapter
[] 16-ga Red/Black cable (100' + 50')

==== Misc ==========
[] Compass
[] GPS
[] SPOT tracker
[] Digital recorder
[] Log book
[] Sat frequency chart
[] Pass prediction tables
[] Medium backpack