[Icom] RE: Filtering at 9 MHz vs. 455 kHz

Sun, 15 Sep 2002 23:43:41 -0700

Hi Wade,

If you look at the "Underside of chassis" picture on my homebrew transceiver
page

http://www.qsl.net/ab4oj/1ststeps/homebrew/homebrew.html

you will notice a rectangular shielded mixer compartment at the bottom
right, with an elongated shielded IF area just above it, running p the right
side of the chassis. The horizontal partition between those two compartments
(at the bottom of the IF area) is the shield which straddles the 9 MHz IF
filter (visible in the "Top view of chassis" picture).

If you are concerned about blow-by around a 9 MHz filter in any of your
rigs, you can probably install a similar shield partition - just make sure
it is  properly earthed to chassis.

Cheers for now, 73,
Adam VA7OJ/AB4OJ

-----Original Message-----
From: [email protected] [mailto:[email protected]]On
Behalf Of Wade Millwood VK4ACB
Sent: Sunday, September 15, 2002 18:59
To: [email protected]
Subject: Re: [Icom] RE: Filtering at 9 MHz vs. 455 kHz

G'day Adam

From the sound of all that you and others have said about blowby with
analogue IF systems, there must be room for improvement with a lot of rigs,
ie shielding can be improved.

I must admit looking at a lot of my gear, on most there is no shielding
between the input and output pins on IF crystal filters.

I find these pages a very useful resource, thanks.

Regards

Wade VK4ACB