[aprssig] Need help testing 30m HF APRS in the Northwest

[Ben Jackson]

On Sun, Jul 30, 2006 at 09:11:33PM -0700, Ray McKnight wrote:
> You've made no comments as to what your antenna is and how it's mounted.

It's an L-shaped dipole, indoors.  It's not quite half wavelength,
more like 48% since I couldn't tune it when it was exactly 1/2.
The L points southeast, which is probably the worst direction based
on known digis.

It's tuned with a modified Z-match using a "red LED SWR bridge".

> What TNC did you say you had and what's the tone pairs?
> And you rig?

It's all home built.  The idea was to create something very simple for
APRS use only.  It's a VCXO at 25MHz - 14.85MHz (SA602A) (both crystals
available at Digikey).  The output of that is buffered by a 74HC240
inverter and that drives 4 other inverters.  I've used that output
directly (about 400mW w/8V into the '240) and used that to drive an
IRF510 with up to 12V input.

(yes, there's an output low pass filter)

> Make SURE you're on freq first, then work on the antenna issue.

I used a signal generator to zero-beat WWV at 10MHz and used that to
calibrate a frequency counter.  I've even swept about 100Hz at 10Hz
increments (constant 200Hz mark/space interval).

-- 
Ben Jackson AD7GD
<ben at ben.com>
http://www.ben.com/