[TenTec] Omni-VI+ Phase Noise and INRAD roofing filter mod?

[Duane - N9DG]

RE LO noise measurements - Note that the Sherwood
measurements are not very consistent for the spacing used to
measure the LO phase noise:

Orion (II)  10kHz
Corsair      4kHz
Omni VI+    20kHz

It's really too bad Bob didn't pick something in the range of
3-5 kHz as the standard spacing for the phase noise
measurement tests for all of the radios he tests. With the
test spacing all over the place it is hard to make any direct
comparisons between radios for LO phase noise performance.

Duane
N9DG

--- Bill Tippett <btippett at alum.mit.edu> wrote:

> 
> 
>          More data from:
> 
> http://www.sherweng.com/table.html
> 
> Sherwood has been making these measurements
> consistently over many years:
> 
> Transceiver     10 kHz LO Noise IMD 20 kHz      IMD 2 kHz
> Orion                   -130            96              93
> Corsair         -132            93              79 (@ 3
> kHz)
> Omni VI+                -137            97              80
> 
> where LO Noise = Phase Noise
> 
> Again, I would expect an properly modified Omni VI to
> have equivalent IMD performance as Orion at 2 kHz.
> 
>          Here's another comparison by Inrad of Omni's
> IMD using stock, 600 and 2400 Hz roofing filters:
> 
> http://www.qth.com/inrad/kits.htm#tentec
> 
> Spacing         OEM      600 Hz filter  2400Hz filter
> 2 kHz           79 dB   94 dB           85.5 dB
> 5 kHz           82.5    97              95.5
> 10 kHz  86.5    98              96.5
> 20 kHz  95      97.5            97.5
> 
>          These measurements cannot necessarily be
> compared directly (i.e. RSGB vs Sherwood vs Inrad)
> because they use different spacings, measurement
> methodologies, equipment and testers.  However,
> they are probably internally consistent within normal
> sample and measurement errors.  From what I see
> and know about the Inrad mod, I would probably
> choose a 600 Hz Inrad modified Omni over the
> Corsair for CW operation.  Remember however
> that the 600 Hz filter will not be inline when you use
> Omni on SSB!
> 
>                                  73,  Bill  W4ZV
> 
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> 


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