[DSP-10] DSP10 Birdie.

[Bob Larkin]

Hi Chuck,

Yes, I think your internal birdies are real!

On 13 Dec00, Lars Sj=F6berg, SM2GCR, in an email to this group pointed out
some birdies in his DSP-10. I found the same ones, and some more. These
would seem to be the same ones that you are seeing now. I was able to
calculate the harmonics of the two oscillators that produced these, but I
seem to have lost my notes!

In any event, there is always the possibility of moving the LO in a
transceiver when one is being used, and correcting this in the uhfa.cfg
file. For direct two meter operation, it is not so simple, especially if an
external 10 MHz reference is being used. If the external ref is not being
used, you can still offset the LO and correct it in software using the
uhfa.cfg file entries for all the tvtr that apply to 2-meters. What you are
doing is pretending that the offset is due to a transverter that converts
from, say 10 kHz, away. this offset can be either plus or minus.  At least,
I think this should work, but I have not tried it! =20

--------------Clipped from 19Dec00 email from me -----------

I did some birdie hunting. I seem to see the same ones that Lars sees, and
was able to find a few more:
144.310  -119 dBm
144.690  -143
145.620  -117
146.490  -119
Those were from Lars, and
144.300  -122
144.000  -126
145.000  -117
148.000  -113
I am using an external reference, and the even MHz could possibly come from
that, so don't be surprised if you don't find those.

I do not, however, see the 5 kHz birdie at all any more, with the software=
 fix.

And of course, when you hook an antenna on there are urban birdies literally
everywhere. I don't think we can do much about that, and I am at the edge of
town.

A challenge: The 145.620 one is one of the stronger ones. Here are the
frequencies involved. Can anyone figure how it is being generated (I have
not tried and do not have the answer):
1st LO Freq  125.955000 MHz
1st I-F       19.664000 MHz
2nd LO        19.680000 MHz
2nd I-F       15.600    kHz
Those frequencies put the signal at exact zero beat.

-----------------------------------------------------------------------

73,  Bob  W7PUA



At 06:27 AM 9/8/03 -0700, you wrote:
>
>I am experiencing a birdies at 144.300MHz & 144.310MHz on my DSP10 and
>they appear at .300MHz in all of my microwave transverters.  This is
>where the microwave beacons are located.  Is anyone else seeing these?=20
>Or have I missed something in the tune up of my DSP10?
>
>Chuck,  WA6EXV
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