[TenTec] Cautionary Tale: Orion 13.8 V connector (long)

[Denton]

The dc connector has been one of my few gripes about TT rigs...from the 580 
delta I had years ago, the Pegasus I used to have, the current Omni 6 and 
the Omni 7 that is on its way back to TT for a look see and possibly some 
repair. My current Omni 6, I pulled out the dc cable connector and installed 
a pig tail with a much stouter dc connector...30 amp power poles.
I will probably clip off the TT male connectors to about 1/4 inch of the pc 
board inside of the Omni 7 and install a powerpole pig tail in its place.
----- Original Message ----- 
From: "Dick Green" <wc1m at msn.com>
To: "Ten Tec Reflector" <tentec at contesting.com>
Sent: Tuesday, May 29, 2007 11:57 AM
Subject: [TenTec] Cautionary Tale: Orion 13.8 V connector (long)


> Hi,
>
>
>
> I want to warn everyone about a problem I encountered with the 13.8 VDC
> power connector on my Orion I. Over time, stress on the cable can deform 
> the
> pins inside the connector, resulting in intermittent contact and/or a high
> resistance connection. If the resistance gets high enough, the voltage
> inside the radio will drop below spec when transmitting, causing the Orion
> to crash and reboot. There can be other odd symptoms before a crash 
> occurs,
> such as the LCD backlight flickering and audio artifacts in QSK operation
> (I'm sure that will get the attention of many on this reflector -- see the
> end of this mesage.) In my case, the high-resistance connection also 
> caused
> burn marks inside the plastic connector on the hot side. This made me 
> wonder
> if the problem could present a fire hazard.
>
>
>
> In my opinion, the connector arrangement is flawed because one end is
> rigidly fixed to a PC board inside the radio and the other end is attached
> to the cable. Repeated wiggling of the cable will cause the split male 
> pins
> in the cable end to compress, while the female pins at the radio end 
> expand.
> Eventually, they begin to lose contact with each other. Pulling a lot of
> current through the resulting high resistance junction causes the pins to
> heat up, leading to discoloration of the metal and burning of the
> surrounding plastic. I believe heat plays a role, making the symptoms
> intermittent. As you transmit, the connector heats up from drawing high
> current across the high resistance junction, the female pins expand even
> more, the resistance increases, and the voltage drops below spec.
>
>
>
> I've had my Orion for about 3 1/2 years. It's been moved around a few 
> times
> and was taken on a trip once, but I wouldn't say the cable has had 
> excessive
> stress put on it beyond what would be normal in most shacks. I considered
> ordering a new PC-mounted connector and power cable from Ten-Tec, but
> decided to install a more rigid system. I ended up soldering the cable
> directly to the PC board in place of the connector. I passed the cable
> through a rubber grommet to keep it from abrading against the sharp edges 
> of
> the rectangular connector hole in the chassis, and used a small cable tie 
> to
> clamp the cable down so it can't move inside the radio and put stress on 
> the
> solder junctions. I suppose it's a bit of a kludge, but is superior
> mechanically to what was there before. The downside is that the cable is
> permanently attached to the radio. I can live with that, but others may 
> not
> like it.
>
>
>
> Many mobile rigs have the power cable pass directly into the radio through 
> a
> strain relief, and the connectors are a few inches down the cable away 
> from
> the radio. I believe this arrangement puts less stress on the connectors.
> Also, I've seen much higher-quality connectors used for mobile rigs, which
> probably aren't vulnerable to the problem I encountered. Although it would
> result in a little pigtail hanging out of the back of the Orion, such an
> arrangement would be superior to the current design. If that's not
> acceptable, I'd recommend a completely different type of power connector.
>
>
>
> The story of how I discovered the problem follows. Some may find it
> interesting or helpful for diagnosing their own connector problems.
>
>
>
> I operated CQ WPX CW this weekend. In the weeks before the contest, I had
> noticed some mild flickering in the LCD backlight on transmit, which I had
> not seen before. I meant to look into the problem, but didn't get around 
> to
> it.
>
>
>
> I had great runs on 40m to Europe during the first two hours, about 235
> contacts, and then the rate dropped off. I turned on the CQ repeat loop 
> and
> the Orion spent at least an hour or two calling CQ. The Orion was driving 
> an
> Alpha 87A amp, which needed about 70W of drive to put legal limit power on
> my 2-el 40m beam (SWR about 1.5:1 at the bottom of the band.) I noticed 
> that
> the LCD backlight flicker seemed to be getting worse. All of a sudden, I
> heard a loud pop in the headphones, several relays inside the Orion 
> snapped
> loudly, and the firmware rebooted. I've never seen that before -- usually 
> a
> crash kills  the radio and I have to cycle power. But the Orion came back 
> up
> by itself and appeared to be working normally again, except for the LCD
> backlight flicker.
>
>
>
> About 20 minutes later, I had another crash-reboot. Again, the radio
> recovered by itself. Pretty soon, the Orion was going through the
> crash-reboot sequence every few minutes. I was forced to switch run
> operation to my FT-1000D. I had loaded the latest V2.062a firmware before
> the contest (I like to live dangerously) and thought perhaps it was the
> culprit. I backed up to a previous V2 release, but the crash-reboot 
> sequence
> kept happening. I even backed up all the way to V1.363b5, but that did not
> cure the problem.
>
>
>
> I use an Alinco DM-33MV switching power supply with the Orion because I 
> find
> the fan on the stock Ten-Tec 963 power supply to be horrendously loud when
> it kicks on -- even when I'm wearing high-isolation headphones. I checked
> the voltage on the Alinco and found that it was slightly low -- 13.6VDC. I
> increased the voltage slowly, and found that at about 14VDC the LCD
> backlight flicker nearly disappeared. At 15VDC it went away entirely. The
> higher voltage seemed to somewhat reduce the frequency of the crash-reboot
> problem, but didn't cure it. Then I swapped out the Alinco for the Ten Tec
> 963 supply. That supply puts out about 14.22VDC when idle, and the LCD
> backlight flicker was completely gone. However, the Orion would still 
> crash
> and reboot every few minutes. I was beginning to think  the finals were
> shot, or perhaps an internal voltage regulator was failing.
>
>
>
> Later in the contest, I realized that if I reduced power to 30W the Orion
> would not crash. This drove the 87A to put out 500-750W, depending on the
> antenna, which was acceptable for S&P work. That's how I limped through 
> the
> contest.
>
>
>
> Late in the contest, I caught a break that saved the radio a trip to
> Tennessee. To battle fatigue, I decided to change my sitting position. I
> have a wireless keyboard that lets me push the chair away from the desk 
> and
> put my feet up with the keyboard on my lap. I reached over to grab the
> Orion's VFO pod, and suddenly the Orion crashed again -- without
> transmitting. I discovered that if I pulled on the cable, the Orion would
> crash. It didn't take long to realize that the pod cable was resting on 
> the
> power cable. I wiggled the Orion's 13.8 VDC connector, and the radio
> crashed. I pulled the connector and saw ugly brown burn marks on the hot
> side. The split male pins were compressed all the way. I tried cleaning 
> the
> male pins and spreading them. This solved the backlight flicker problem, 
> and
> greatly reduced the frequency of the crashes, but did not eliminate the
> problem. Back to 30W.
>
>
>
> After the contest, I popped the Orion's covers and, using an ohmmeter, 
> found
> that no matter what I did to rehabilitate the male and female pins, the
> cable would lose continuity if I wiggled it. That's when I decided to
> replace the connector, as detailed above. After doing so. I ran a CQ loop
> into both 80m and 40m at 100W for 15 minutes each and experienced no
> crashes. I also duplicated the 40m scenario, 70W into the 87A into the 
> 2-el
> 40m beam, and had no crashes for over 20 minutes. It'll take another 
> contest
> to be sure, but I believe the problem has been solved.
>
>
>
> QSK Audio Artifacts: There was some barely noticable LCD backlight flicker
> with the Alinco set to 13.8 VDC, so I increased it to 14.22 V, same as the
> 963 power supply. Now the flicker is gone. In the course of playing with 
> the
> input voltage, I was surprised to hear the tail-end clicks in the QSK 
> audio
> significantly reduced when the voltage was increased to the point where 
> the
> LCD backlight didn't flicker. This may explain why some people hear more 
> QSK
> audio artifacts than others.
>
>
>
> The moral of the story is: check your 13.8 VDC connector. Make sure there
> are no burn marks and that the pins are making tight contact. Be sure to
> rout the cable in such a way that there is minimal stress on the power
> connector. If you're really worried about it, devise a better connection 
> and
> let me know what you did.
>
>
>
> Sorry for the long story, but hopefully it will be useful to someone out
> there.
>
>
>
> 73, Dick WC1M
>
>
>
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