May 26th, 2008

Enterprise Bridge

Today's lesson in color coding

...or why you always tone out all the connections when you replace the connector on a cable.

I have a Kenwood TM-V7A dual-band (144/440 MHz) mobile ham radio. A long while back, the RJ-45 plug on the end of the mic cord lost its little retention tab. I cut it off and crimped on a new one. I plugged it back into the radio, turned it on, and it immediately started transmitting. Every time I plugged in the mic, it nailed up the PTT switch. Whiskey Tango Foxtrot?

I looked at the old and new connectors, and they LOOKED identical. I put the whole thing on a shelf until I had time to dig deeper into this. Maybe strands of the mic signal shield were poking into two different wires and shorting it.

So tonight, months later, I finally pull the thing down and look it over. Took the mic apart, toned out each wire. Sure enough, the black one doesn't connect. Okay, cut off the cable, crimp on another one, and make damned sure the black wire goes all the way down its hole. Same problem. OMGWTFBBQ?

I spend the evening looking over the PC boards in the mic (it's a DTMF/remote control mic, a Kenwood MC-53DM.) Nothing's corroded, nothing's shorted, nothing's burned out. I tear aprt the 'net looking for a schematic. I find one for the MC-45DM, the non-backlit version of this mic. Okay, there's a chain of transistors that pulls the PTT when you dial a digit. That's what must be nailing it up. I get an ethernet cable and a coupler so I can hook the mic to the radio and test it live. (Tuned to the aircraft band, the radio won't transmit, it just beeps at first contact to tell you so.)

I find some rather odd voltages. And the DTMF emits no tones. It just makes a squishing noise in the speaker when I dial a digit. There's points that SHOULD be at ground, yet there's a voltage difference, of about FOUR volts, between them and the PTT ground. There's two ground connections in the RJ-45, one is called out on the schematic as being the mic wire's shield. Okay, an analog ground. Well, why the hell is there a difference between the analog and digital ground? You separate them for noise, but they should still be 0V relative to each other. Unless the analog ground isn't actually CONNECTED to the place where they finally bond. (In the radio.)

There's a black wire in the cable. There's a black wire attached to the mic's PC boards. Rather, there's what LOOKS like a black wire attached to the PC board. I get no continuity, so I strip the insulation off the mic end... the wire at the RJ-45 end is copper colored. This is not. This is silvery. Like the mic shield. It's got a very thin piece of heat-shrink tubing on it.


Clip the RJ-45, attach another one, using the twisted shield line instead of the black wire. It's REALLY tricky now because I'm starting to get into the coiled part of the cord. And I'm back in business.
Enterprise Bridge

DSL service charge

Some of us on IRC were talking about this the other day, as a couple of people are getting really shitty service from their cable companies, and the landscape has changed since they last had or considered DSL service.

Rather quietly in 2006, Pac Bell dropped its requirement that ADSL service had to be bundled with analog voice. I found this out from a promotional e-mail from Speakeasy (I'd been a happy customer since 2003, when I finally left Cox for fucking with me,) promoting their OneLink ADSL service--DSL over a dry pair. This was coupled with their new VoIP offering, which featured free long distance both domestically and to 22 major foreign countries. ADSL on a dry pair? I called and asked "O RLY?" They said "YA RLY!" I said "SINE ME UP!"

So here's what I'm paying...

  DSL: Home Select Plus OneLink ADSL 1500/768 kbps
    Monthly line charge                      $95.95
    Regulatory Compliance Fee                  5.71
  Home VoIP:
    Monthly service charge                   $27.95
    Regulatory Compliance Fee                  6.20
  Total                                     $135.81

They like to auto-bill credit cards. I think there's a service charge for conventional send-and-mail-payment paper billing.

Last March, Best Buy bought Speakeasy. Since then, nothing has changed. Not the name, not any kind of branding, and not the service. It's the same, excellent, professional service that understands that I Fucking Know My Shit™. When I call in for customer support, I get someone who also knows their shit, who is not bound to a script, who believes me if I tell him I can ping the gateway but can't reach anything beyond it. Or that yes, I run an SMTP server, but it's Postfix (not Sendmail) and I have unauthenticated relaying turned off. They can work with average-Joe users, but if you're an industry professional (or even just a gifted amateur,) this is the provider for you. Hell, I get e-mail advice of upcoming service outages, and they never use the whole window. Often, I don't even notice it.

The VoIP offering is run by Level 3, rebadged for Speakeasy. It uses the same Motorola terminal adapter as Vonage. I've been fantastically happy with the voice quality. The only hiccup is that the voice codec used does not support fax above standard resolution. If you've got to have fine or better resolution fax capability, you have to find an IP fax service. The unlimited international LD is to non-mobile numbers in Austria, Belgium, Canada, Chile, China, Denmark, France, Germany, Hong Kong, Ireland, Italy, Malaysia, Netherlands, New Zealand, Norway, Singapore, South Korea, Spain, Sweden, Switzerland, Taiwan, and the United Kingdom. If you call a mobile number, I don't think you pay full price, I think it just covers the airtime (since it's caller-pays pretty much everywhere but the US.)