RE: [linrad] RE: Hardware

[conrad@xxxxxxxxxxxxxxxx>]

In a word yes! I expect that Jim UWA and I will be going down a similar
route, perhaps between us we could get something up on a website. My initial
system will consist of
1. A 2m preamp which could be bought off the shelf or built depending on
skill/resources/inclination.
2.A simple 50 ohm 2m bandpass filter (actually I will probably be using a
DCI one in practice but it would be useful to design something simple). This
could be done with a software package or a pen and paper. In fact there is
probably some info on Leif site already.
3.A 3db attenuator to ensure that the mixer is properly terminated.
4.A schottky mixer, I have decent high level ones so I will use these.
5.A box made from double sided PCB with the appropriate connectors on
it.Everything built dead bug style.

That is all that is needed if you have a decent signal generator to use as a
LO at 141.5 Mhz and an RX2500.

I will probably then build a crystal oscillator for the LO and maybe a 2.5
Mhz amplifier, depending on how Leif is progressing with the other modules.

I will definitely bear the idea in mind Josh, after all you have helped me
plenty!

73

Conrad


-----Original Message-----
From: owner-linrad@xxxxxxxxxxxxxxxxxxxxx
[mailto:owner-linrad@xxxxxxxxxxxxxxxxxxxxx]On Behalf Of
josh-linrad@xxxxxxxxxxxx
Sent: 09 January 2003 18:59
To: Linrad
Subject: Re: [linrad] RE: Hardware



Leif wrote:

> That is not the reason. If you want 144MHz, low end only, a good
> solution would be to use a couple of X-tal oscillators to convert
> directly to 2.5 MHz. If you start with 15.722MHz and add two triplers to
> get 141.5 you will easily be able to pull the crystal 50 or 100kHz on
> 144MHz. The IC202 uses this method to pull 200kHz, but at some stage
> there will be a loss of Q causing too much sideband noise. If you are
> happy with coverage from 144.000 to 144.400 this will give very good
> performance at low cost with easily made hardware.


OK, I don't have a 2.5 MHz input so I need a different frequency, I was
working on going straight to sound card.  But I would like to know where
you find information on building something like this.

I like the idea of low cost and easy, but truly it is hard for me (with
out any building experience) to look at some of the ideas suggested on
yours and w3sz site to know how to build anything.  Rogers two stage
design looks trivial, but then I wonder how it all fits together.  I think
I have an OK idea on some of the pieces.  Others are still a mystery.
And when I once started to make a parts list two resistors did not have
values, and the capacitors did not all have units.  Some people can
probably just know how these were supposed to be used, but for me this is
too much of a jump to make.

The TimeMachine looks to be an OK start for HF, but something is still
needed to go from 2M to HF.  Maybe this is a good starting point for my
next idea, but only if we have a plan to get higher.

Is there soneone on this list that knows enough to lead a hardware
building session.  Something that is simple and cheap, but with enough
steps and notes and pictures that everyone can work on at the same time
and maybe learn how some of this works.  Ideally this can then be archived
in a way that anyone can come later and follow the same process and learn
the same things that we just did.

Is there any interest by others in a process like this?



						Later, JOSH (kd7hgl)






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