[HomeBrew] Homebrewed beacon, KO6BB/B is QRV on 28.248MCs

[Philip KO6BB]

Hi,

I'm posting this here as some list members helped me to bring this project 
in at "nearly" zero cost by providing things like an Xtal, new "Final 
transistor" and advice. I DID have to buy a few stainless steel hardware 
items for the antenna.

I finally got the 10M beacon up and running. Plans call for running it 24/7,
though with NO real-estate for antennas, all 7 antennas (Butternut HF-2V,
Alpha Delta DX-EE, Inverted Vee's for 15 & 10M, two LF active whips and the
new 10M antenna) antennas are unavoidably in closer proximity to each other
than I would prefer (all mounted over my mobile home roof/awnings) there
'may' be times I need to shut the beacon down to prevent receiver desensing
while DXing.

So far all these antennas being close to each other has worked well, but
then I've not tried running "multi" (multiple stations) in any contests etc.
Depending on which antenna/band is in use I can hear the receiver "puffing"
in time to the beacon keying 8^(  The two active whips for LF seem to be
especially vulnerable 8^(  That means that I may have to shut the beacon
down when NDB chasing. . .

Beacon Specifics.
1.  Frequency: 28.248MCS.  May change that later if I receive reports that
another beacon and I are QRMing each other.
2.  RF Power: 7 Watts from "gutted" JC Penny 40 Channel CB.
3.  Antenna: Roof mounted 1/4 wave groundplane over approximately 1200 Sq/ft
of sheet-metal roof/awning.  1.2/1 SWR at the operating frequency and under
1.5/1 between 28.0 and 29.0 MCs.  Under 2.0/1 at 29.7MCs!
4.  Keyer:  Old NEC laptop computer running DOS.

ANTENNA Notes:  I had "salvaged" an old Ringo 1/2 wave CB antenna.  This 
puppy would NOT tune up regardless of what I did.  I suspect the ring may 
have been changed or cut down.  So, the ring was removed along with the top 
couple sections and the antenna configured as a 1/4 Wave groundplane.

Radio Notes:  As mentioned above, the radio is a gutted JC Penny 40 Channel 
rig.  Audio and receive circuitry was removed and the modulation Xformer 
removed and bypassed (for higher supply Voltage to the final).  The TX mixer 
Xtal was replaced with one that gives me about 7 channels at 10KC steps in 
the Beacon Sub-band (28.208, 28.218, 28.228, 28.238, 28.248, 28.258 and 
28.268 MCS).  I selected 28.248 as being nearly in the middle of the 
sub-band.  A keyer interface was installed in the radio consisting of an 
opto coupler and NPN transistor to key the PTT circuit of the radio from the 
RS-232 serial interface of the computer.

A damping capacitor was added across the keying line to dampen key-clicks 
somewhat.  The final and driver transistor was replaced with beefier units 
and heatsink was beefed up.  A small fan was added in the original speaker 
hole to keep things cool in case the keyer locks up in transmit.  The fan 
runs on a reduced Voltage of 6 Volts for low speed operation.  The Output 
power from this "beast" is a mighty 7.3 Watts CW carrier as measured on my 
MFj auto-tuner/digital power meter.

73 de Phil,  KO6BB
DX begins at the noise floor!

THE BEACONEER'S LAIR:   http://www.geocities.com/ko6bb/
MY RADIO-LOGS:       http://www.geocities.com/ko6bb/Logs/
QSL GALLERY: http://photobucket.com/albums/f306/KO6BB/
Merced, Central California,    37.3N  120.48W  CM97sh