[1000mp] Observations After Roofing Filter Install and Other Upgrades

[Dean Fewkes]

Well I did some major upgrades to my Mark V field this last weekend. 
These upgrades
included:

The Inrad roofing filter.
2.8 HTZ Inrad filters for the 2nd and 3rd IF.
Inrad key click mod.
Changed out the old K9AN bonus mod for a .022 capacitor instead of .047.

Here are some initial observations that really stood out:

The roofing filter greatly improved my AM reception and short wave 
listening. This is
because the puny ceramic AM filter used in the 3rd IF let way too much 
stuff blow by
including hi-pitched whines etc. The roofing filter STOPPED this with 
only a slight
reduction in observed fidelity. It is now what I would call the perfect 
filter width for AM.
If you want hi-fi, you can use the synchronous receive feature because 
it needs only one
sideband and the carrier of the AM signal and is not restricted at all 
by the roofing filter.

The noise blanker causes much less distortion and works just as well, 
thanks to the
roofing filter.

The clicks that are normally heard in the headphones of the Field model 
while working
QSK are gone, and the S meter pinning that is often associated with QSK 
is gone. I am
not sure if these improvements are due to the roofing filter or the key 
click mod.

As advertised, the roofing filter does reduce or eliminate interference 
from strong signals
that are near your operating frequency.  For those of us that must use 
the noise blanker at
times, this improvement is very significant. Without the noise blanker 
the improvement is
more subtle but still definitely makes a difference.

The change in the old K9AN bonus mod made the CW audio quality a little 
less
restrictive and smoother when using the wide filters. I thought the .047 
blocked too much
hi-pitched reception when wanting to listen to a wide pass-band. This is 
really a personal
preference.

I hope this information is helpful and I will probably add more after 
further use.

Dean Fewkes
KG7MZ
Kalama, WA