[hpsdr] Mercury Spurious Emissions

[Jeremy McDermond]

On Sep 10, 2011, at 12:00 AM, Helmut Oeller wrote:

> Hi Jeremy,
> 
> It's possible that you receive the 122,88 Mc sampling clock due to a bad
> image rejection of the FM rig, if its if is around 10.7 Mc. In particular
> hand-held FM rigs have bad selection in the frontend. 

I have checked on the IF frequency of the TH-D7A, and the first IF is supposed to be at 38.85MHz on 2m.  

From Steve's dataset, it seems like it's harmonics of 3.072 that are being radiated somehow.

I'm seeing signals at:

Signal -- Harmonic (predicted frequency)
------------------------------
138.245 -- 45th (138.240)
Not Hrd -- 46th (141.312)
144.385 -- 47th (144.384)
147.455 -- 48th (147.456)
150.525 -- 49th (150.528)
Not Hrd -- 50th (153.600)
156.675 -- 51st (156.672)
159.745 -- 52nd (159.744)
162.815 -- 53rd (162.816)
Not Hrd -- 54th (165.888)
168.960 -- 55th (168.960)
172.030 -- 56th (172.032)

402.435 -- 131st (402.432)
405.505 -- 132nd (405.504)
408.575 -- 133rd (408.576)
Not Hrd -- 134th (411.648)
414.720 -- 135th (414.720)
417.795 -- 136th (417.792)
420.865 -- 137th (420.864)
Not Hrd -- 138th (423.936)
427.005 -- 139th (427.008)
430.080 -- 140th (430.080)
433.150 -- 141st (433.152)
436.225 -- 142nd (436.224) -- Weak
439.295 -- 143rd (439.296)
442.365 -- 144th (442.368)
445.440 -- 145th (445.440)
Not Hrd -- 146th (448.512)
451.585 -- 147th (451.584)
455.655 -- 148th (454.656)
457.725 -- 149th (457.728)
460.800 -- 150th (460.800) -- Weak
463.870 -- 151st (463.872)
466.945 -- 152nd (466.944)
470.015 -- 153rd (470.016)
Not Hrd -- 154th (473.088)
476.160 -- 155th (476.160)
479.235 -- 156th (479.232)

So, it appears as though the theory of 3.072MHz harmonics is correct, although it appears as though every 4th harmonic is being suppressed by something.

> 73 Helmut, DC6NY

--
Jeremy McDermond (NH6Z)
Xenotropic Systems
mcdermj at xenotropic.com




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