[TenTec] Paragon I (585) Roofing Filter

[Dr. Gerald N. Johnson]

On Sun, 2007-02-04 at 20:32 +0100, Alec Otulak wrote:
>  
> Hi Dears,
> 
> re: Paragon I (585)
> 
> I need Your help in getting information on
> the impedance and load capacitance of Paragon's 75MHz
> filter (Y1)located on the Second MiXer board (81332)
> as I am truly devoted to the idea of installing
> a roofing filter there.
> 
> I have directly emailed Ten-Tec about it a dozen times
> but still got no response whatsoever.
> 
> Will You then be so kind to sift through Your databases
> to find the information and revert with it,
> please ?
> 
> I will appreciate that very much,
> Yours,
> Alec/SP2EWQ
> 
>  
Are you sure the first oscillator does all the fine tuning? Sometimes
with that architecture the first oscillator goes in 10 KHz steps and the
finer tuning is in the second oscillator and so that low VHF filter has
to be wide to allow that to work.

If the first oscillator does the fine tuning, you should be able to
detect with a strong signal checking for blocking that the blocking of
the second mixer has a frequency range symmetrical about the receive
frequency for all receive frequencies over a 50 KHz range on a band. If
the first oscillator has larger steps that blocking frequency range
should show considerable asymmetry at some frequencies.

Of course if the second oscillator is a single crystal on 75 - 9 MHz
then I'm all wet.

-- 
73, Jerry, K0CQ,
All content copyright Dr. Gerald N. Johnson, electrical engineer