[CRAPRS] FW: Radio Problems

[Gary Bishop]

Ah, the joys of running the TH-F6A.  I suspect the following:

The remote mike button functions are wired as different resistances into the mike circuit.
Like remote mike button 'A' is a 10k resistance, remote mike button 'B' is a 15k resistance
across the mike circuit, etc.  I don't remember the exact values, but you get the idea.

I've found that the after market plugs don't quite fit into the jacks properly on the side
of the radio.  The jacks are recessed slightly, meaning the outer shell or cover for any
external plug must be very thin.  This
means the plugs are almost, but not quite, seated into the radio jacks.  When this 
happens, the slightest movement outward on the plugs will trigger a channel change,
vfo mode switch, or some other strange behavior in the radio, even if you lock the
functions.  I think the lock only affects the buttons on the radio, not the external
mike functions.  


Even if you bought the cable from the open tracker folks, it may still just use more
standard sized plugs.

If you made your own plug, be aware that the ground or return for the mike circuit is not
the shell or shield on the (larger) mike jack; it's the shell on the audio output jack.

I have a cable I made from external parts, with very narrow shells, that do seat properly
into the jacks.  I can let you borrow it.

Or maybe better yet, I have a known-good
Radio Shack HTX-202 you could use. It uses the more standard wiring for audio and mike:
the larger 3.5 mm or 1/8 inch for external speaker, 2.5 mm or 3/16 for the mike, with
a 10K to ground to key the thing.  When powered by 12 volts, it's rated to 5 watts out,
and the usually measure pretty close to that.  BNC RF connector, standard barrel sleeve
for input power.  

Everything about the Kenwood is odd, as far as connectors are concerned.


> Date: Wed, 4 Feb 2009 16:35:58 -0600
> To: craprs at rf.org
> From: info at n-connect.net
> Subject: [CRAPRS] Radio Problems
> 
> Posting from the CRAPRS mailing list:
> I've got an Opentracker2 in my truck connected to a KenwoodTHF6A, and 
> an external antenna.   It's a "waste" of a tribander to use it on 
> APRS, and I've got another HT on my list of radio gear to acquire, 
> but for now, the Kenwood is all I've got.
> 
> The problem I'm having with it is that it changes channels. 
> Completely randomly.  Sometimes it's fine for weeks, and other times, 
> it changes channels after only a minute of use.  It's worse when I 
> run it off it's internal battery, so I run it off 12 volt vehicle 
> power.  And it's random.  It will randomly change to some memory 
> channel.
> 
> I've got some snap on chokes, for the mic and audio cable, but they 
> don't seem to have any effect. Running off the HT's antenna (crap for 
> getting packets out, but I wanted to test it) or external roof top 
> mag mount doesn't make any difference.  Normal power is 5 watts. 
> I've run it on .5 watts, and .05 watts, and have seen no difference. 
> And yeah, you CAN actually get some APRS packets out on .05 watts. 
> But not many, and not far from a digi.  :-)
> 
> I've set it to one band use only, and always run it with the controls 
> locked when I use it as an APRS radio.  I also run it in VFO mode, 
> since I do not have a memory setting for 144.390.  So VFO, one band 
> mode, controls locked, and it still manages to change to some random 
> memory channel.  Since I have a lot of channels in memory that I 
> can't transmit on, (radio works well as a scanner too) I usually land 
> on one of those channels, so it's no real harm.  But one of these 
> days, I'm going to land on a repeater channel, and blast it with APRS 
> packets.
> 
> And that day was today, when I noticed it was on 444.225. (Dubuque?) 
> I'm not sure if that is a working repeater, or not.
> 
> And it stays locked during the channel change.  I have to unlock it, 
> and change it back and relock it.
> 
> Anyone have any ideas?
> 
> _______________________________________________
> CRAPRS mailing list
> CRAPRS at rf.org
> http://rf.org/mailman/listinfo/craprs

_________________________________________________________________
Windows Live™: E-mail. Chat. Share. Get more ways to connect. 
http://windowslive.com/online/hotmail?ocid=TXT_TAGLM_WL_HM_AE_Faster_022009
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://rf.org/pipermail/craprs/attachments/20090204/dedba220/attachment.htm