Re: Questions from a newbie...

Allison Parent <kb1gmx@...>
 

Hello Roy,

I've put inline comments.

--- In BITX20@..., "Roy E. Ruivivar" <Roy.Ruivivar@d...>
wrote:

Arv / Rahul,

Thank you for the reply. As Rahul suggests, I'll try the 2SC1815. I
have lots of it and they are relatively cheap. I think I'll try to make
a CW Version first just to get a feel for the wide bandwidth as Arv
suggests on the Crystals ( 2 x 16 Mhz / 2 pole, for 5 Mhz VFO for a
BITX15 CW only).
For a decent CW or SSB filter the crystals need to be within 100Hz
or less. Even 3 poles will be weak for a CW filter in active bands.

This way I can try the 10.7 Mhz Ceramic Filters/Resonators later on. I
found a store that sells them really cheap. I think they don't know
what these are used for... hihi.
Ceramic resonators are lower Q devices than crystals and do not make
good narrow band filters.

One caveat of the BITx is the filter is important. There are few
tuned circuits and filters with out of band responses are not
desireable. Filters I've built with ceramic resonators and filters
do tend to have excess bandwidth and out of band responses.

BTW, does the principle for Testing the 10 Mhz Crystals and computing
for the capacitors applicable for the Ceramic Resonators? Maybe I'll
just try it and post my findings later.
It's possible to use any crystal in the range of 6-20mhz is matched
with the correct termination and coupling capacitors. Old 27mhz
crystals (at fundemental 9mhz) are very good for this too.


Allison
KB1GMX


Thank you very much.

ROY

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