[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

FW: RE: Linrad Questions (Leif Asbrink Oct 08 2002)

-----Original Message-----
From: owner-linrad@xxxxxxxxxxxxxxxxxxxxx
[mailto:owner-linrad@xxxxxxxxxxxxxxxxxxxxx]On Behalf Of Leif Asbrink
Sent: Tuesday, October 08, 2002 3:05 PM
To: linrad@xxxxxxxxxxxxxxxxxxxxx
Subject: RE: [linrad] Linrad Questions

Hi Terry, 

>      A few questions.   I currently have Linrad running under RedHat 7.3 
> using a very old SB16 sound card and taking the receive audio from a 
> Kenwood TS-850SAT.
>     Could some one give me some good starting values to use in setting up 
> Linrad?   I really don't know which ones to play with.
It depends on what you want to do.

>     I am thinking of building aKK7B direct conversion binaural 
> I-Q receiver 
> but don't know how much difference it might make.    Is it worth 
> the effort 
> to go to a direct conversion radio with IQ output?   With two kids in 
> university and another going next year ham radio funds are very limited 
> here. 
The component cost for a direct conversion receiver is close to nothing
if you make 74HC4052 or 74HC5053 mixers and skip the anti-alias filters. 
Performance will be good enough for many purposes.

If it is worth the time/money to go to a larger bandwidth depends
entirely on what you want to do. Is noise blanking important or not?
The blanker improves with larger bandwidth but otherwise bandwidth 
will not affect sensitivity for weak signals. Do you have strong
signals from nearby amateurs? If that is the case you need a 
sophisticated IQ receiver that has adequate dynamic range. In a good
location the simplest solution will be good enough.

> If you do how do you net the your transmit frequency?
Typically the tx and rx are separate so you watch the tx frequency 
on the Linrad screen. If you use Linrad with a single transceiver, 
just act as if you did not use Linrad.


Leif / SM5BSZ