Wednesday, November 29, 2006

WMR PowerGate 40 Backup Power System

A major reason I got my ham ticket was because I wanted emergency communications. I have a pretty good home setup for VHF/UHF in the form of a Yaesu FT-7800R hooked up to a Comet GP-3 antenna on my roof. What I haven't had, up until now, is some form of powering the radio if the power goes out.

Early last week I placed an order with West Mountain Radio for a few items:

  • A PWRGate PG40 backup power system.
  • An MK brand 73 amp hour gel cell.
  • Cables to connect the PowerGate to my Yaesu power supply and to the gel cel, along with my FT-7800R and VX-5RS HT.

The PG40 and cables came the next day but the gel cel didn't arrive today; it's dropped shipped from the manufacturer's warehouse.

The PWRGate has three power connectors:

  • Power in from a DC power supply, which in turn is plugged into mains power.
  • Power out to the radio.
  • Power to the battery for a trickle charge. This port also accepts power in from the battery.

The connectors are Anderson Power Poles.

During normal operation with mains power, the PWRGate provides a trickle charge to the gel cel and DC to the radio. If the battery drains down it could take a few days to recharge once mains power returns, so at some point I'll get a separate battery charger.

If the mains power goes out then the PWRGate's internal switch reconfigures the unit to take power from the battery and provide it to the radio. The power source transfer is seamless, requiring no user intervention, and when I tried it out I didn't notice any difference in the audio I was listening.

The reasons for using a gel cel are that (a) they're safer than lead acid batteries that you need to worry about keeping equalized since they are maintenance free, and (b) they are rated as spill-proof and don't give off fumes. Being a deep cycle battery, it can safely be discharged down to a low level without harm.

Here's a pic of my setup:

The PWRGate is the finned black thing sitting on top of another black box, which is my DC power supply. The leftmost cord plugged into the top is the power input, the middle is power to the radio, and the right hand one goes to the gel cel. The black square on the red cable to the cel's positive lead is a fuse holder. (I have a temporary cover over the gel cel as a protective measure so nobody accidentally shocks himself.)

Future refinements to this system will include a battery box to protect the gel cel and anybody who get a bit careless, a battery charger, and a cable with Anderson Power Poles on one end and a cigarette lighter receptacle on the other so I can power 12V devices including charging cell phones.

Tuesday, November 21, 2006

Backup Radio Power

The major thing missing from my ham radio setup has been a backup power source. With Winter just around the corner I decided that it was time to remedy this. Today I placed an order with West Mountain Radio for several items:

  • PWRgate 40 package
  • 73 ah gel cell
  • Cable for my VX-5RS
  • Cable for my FT-7800R

The cables have an Andersen Power Pole connector on one end, for plugging into the PWRgate, and the appropriate connector on the other end for plugging into the radio.

The PWRgate allows one to create an uninterruptable power supply for radios. Ugly ASCII diagram:

[A/C power] – [PWRgate] – [Gel cell]

This provides the same basic functionality as a UPS intended for computers. If the mains power goes out an you're using the radio, it will automatically shift over to the gel cell. While the radio isn't being used, it will trickle charge the battery.

My Yaesu FT-7800R consumes only 0.5A in RX mode (squelched) and 8.5A when transmitting, so if I'm just monitoring during a power outage, the 73 ah gel cell should last quite awhile. My VX-5RS HT uses a max of 1.9A when transmitting, so it'll last even longer.

At some point I may invest in a generator but for now our power is sufficiently reliable that I don't feel the need yet.

Monday, November 20, 2006

Cross-platform encryption

I want to save digital copies of important documents on a USB stick, but want to secure them against unauthorized access if the drive gets into the wrong hands, because it would be an identity thief's wet dream. The stick will be part of my household emergency kit.

Today I discovered jFileCrypt, a cross-platform encryption/decryption tool written in Java, and which can run on any platform with Java 5. Aside from the fact that it's free (GPL) software, being platform-independent is what I really find attactive. JFileCrypt supports Blowfish so the resulting encrypted file should be secure.

Alternatives include Mac OS X's built-in ability to create encrypted disk images and GPG. Unfortunately, an ecrypted Mac disk image isn't cross platform, and GPG can be confusing, although I've been playing around with it and I'm getting a better understanding of it. For Windows and Linux users, TrueCrypt looks like a good alternative.

Ideally, I'd like to have an ~500 MB encrypted file or folder on a 1 GB USB drive. On the unencrypted portion I'll keep a copy of the encryption utility so that if necessary, I can decrypt the information even if I don't have access to one of my computers. The password I'll be using is long, non-obvious, and has zero significance to anyone other than me.

If any of my readers have suggestions for cross-platform encryption software that would be suitable for this application, please post them as a comment.

Wednesday, November 15, 2006

Good 2M Propagation Tonight

So I'm sitting here in Plymouth Mtg., PA scanning through the freqs on my radio and I picked up the Carbon County ARES net coming in loud and clear. Their repeater is located about 60 miles away in Jim Thorpe, PA. I checked in and introduced myself. Net control gave me a good signal report, even though I was transmitting with only 10W. According to him, there were some "scrambled eggs" in the background but I was totally intelligible.

Even though VHF FM is often said to require line of sight, there are a lot of hills between the repeater and me, so I think the knife edge effect is in play.

My rig is a Yaesu FT-7800R 2M/70cm dual bander, with a Comet GP-3 antenna on top of a 5 foot mast on the short chimney sticking out of my roof.

A few minutes later a station from Sussex County, DE checked in and reported that he too was hearing the repeater clearly. He noted that he also was able to bring in Martinsburg, WV shortly beforehand. Impressive!

Nice to know I can communicate out that far without much infrastructure (or will be, once I get a battery backup in place for my shack).

Tuesday, November 14, 2006

When the lights go out

Back in August I posted about coming shortfalls in reliable electrical power.

The [Electric Reliability Organization] projects that U.S. demand will increase by 141,000 megawatts (MW) over the next 10 years. Supply, however, will increase by only 57,000 MW, and that assumes that all currently proposed new facilities are approved and built.

The system will be operating below the marginal capacity needed to ensure supply reliability at all times. In other words, in peak periods like heat waves, there won’t be enough electricity to go around. Blackouts will inevitably result.


Read the rest of the article here. [H/T to InstaPundit.]

Now, it won't be the end of the world if this comes to pass. However, reliable electricity is something that most Americans have come to expect as a given, much as if it was air. It will take getting used to, and points to the value of implementing alternatives for when grid power is down.