Topband: Content filtered message notification

[Bill Tippett]

"Raoul Coetzee" <raoulc at smmcape.co.za> wrote:

> I am having a bit pf a problem with a second harmonic when operating on 160m. This is of course falling in the 80m band segment and causing mild to severe qrm to my local 80m friends on phone.

        I had a similar problem when we gained SSB access to 3600 and
above.  My solution was a shorted 1/4 wave stub for 160 at the output
of my amplifier.  Use (246/1.83)*Vf to determine the length in feet
and cut it a little longer if you aren't certain of the velocity
factor of your coax.  I used an MFJ-259B analyzer and pruned the stub
for minimum impedance at 3.615.  Just remember to switch out the stub
for other bands!

        I had reports that my harmonic was S7 before I did this.
Afterwards I had W0FLS check it using his 4-Squares on both 80 and
160.  On 160 I was S9+30 and on 80 I was inaudible, and I've not
received further complaints from anyone.

                                       73,  Bill  W4ZV