开云体育

Hi all,
I had the intention to build this transceiver when a friend of me
brought this Yahoo group under my attention.
Too bad, now I spend all the time on reading all information instead
of building it ;-)
The nice thing I like is that the design is so basic, so
straightforward and everything (except the final stage) broadband
that it can be adjusted easily to everyones needs.

Because I have several x-tals with a frequency of 4.9152 MHz this
will be the IF frequency and because I want to make it for 18 Mhz, I
will try to cover the phone part with a VXO on about 13 MHz.

Looking at the pictures of other builders, I see several 'islands',
I do not build that way, I just solder every component to each other
(above the copper surface, only connected to it where needed).

What I also saw is that the x-tal filter has no kind of shielding.
Is it worth seperate the input/output of the filter with a kind of
shielding to prevent the signal passing it?

Good luck all,
Chris, PA3CRX

On Jun 27, 2004, at 6:16 AM, vdberghak wrote:

Looking at the pictures of other builders, I see several 'islands',
I do not build that way, I just solder every component to each other
(above the copper surface, only connected to it where needed).

The only reason(s) I can think of _not_ to make 'em float in the air is that this technique has the potential to make the circuit sensitive to microphonics. And in a high-vibration or high-shock environment such as portable or mobile use, the solder joints would tend to fracture and eventually cause intermittent failures long before any visual breakage was apparent.

What I also saw is that the x-tal filter has no kind of shielding.
Is it worth seperate the input/output of the filter with a kind of
shielding to prevent the signal passing it?

Well, you could take the PCB scraps you saved by not using "island" construction, and use it to make shielding.

What's that old bromide -- "You can never be too rich, too thin, or have too many friends" -- add to that the idea that your electronics can never have too much shielding.

Jim N6OTQ