----- Original Message -----
From: "Michael Babineau" <mbabineau.ve3wmb@...>
To: <
[email protected]>
Sent: Thursday, July 19, 2018 6:51 AM
Subject: Re: [qrp-tech] NE4040B Project
I did some more poking around on eBay and I see that it is still possible to
get HC-49/S crystals for around $5 for 50.
They have 8.192 Mhz (30 m) and 4.000 Mhz (40m) ones available which is what
the parts list for the NE3040/NE4040 calls for.
I had very good luck with the HC-49/S in my NC40a build so I will plan ahead
to use the same for this project and avoid
delays waiting for the "slow boat" to arrive.
Looking at the NE4040 schematic, I wasn't previously aware that the crystal
filter only had 2 crystals in it.
I know that the plan to is "build an NE4040", but I am wondering if adding
another crystal to the filter
(aka using the SW40 IF filter), when laying out the new boards would go
against the spirit of the project ?
(I know that you have to draw the line somewhere, otherwise you might as
well just build an SW40 !)
One thing that I did notice is that the LPF has only 5 elements and I think
that 7 elements is now the norm for better harmonic suppression.
Adding the holes/traces for an extra cap and inductor in the LPF would be a
very simple, but useful, addition when the new board layout
is done.
Cheers
--
Michael VE3WMB / VA2NB
P.S. There is no need for someone to design a new 7 element LPF, as
component values for the W3NQN 7 element LPFs is well documented
in manual for the QRP Labs LPF kits :
