[K3] [Elecraft] Transmit AM through FM Filter?

[Joe Subich, W4TV]

> What do most radios with only 15kHz roofing filters do on AM? 

It's not a matter for the filter bandwidth.  The first IF filter 
is a significant factor in controlling image rejection.  With a 
2nd IF at 15 KHz, the image only 30 away from the desired signal. 

Still, the FM filer response SHOULD be down some 70 or 80 dB 
+/- 30 KHz from the center.  That would be more than enough for 
most purposes - nobody is going to be trying to work AM stations 
at the noise floor <G>.  With 70 dB of image rejection in the 
filter, even if the K3 were driving a 1500 W PEP amplifier the  
transmitted image would be less than .0005 milliwatts of carrier! 

73, 

   ... Joe, W4TV 
  





> -----Original Message-----
> From: elecraft-bounces at mailman.qth.net 
> [mailto:elecraft-bounces at mailman.qth.net] On Behalf Of AD6XY - Mike
> Sent: Sunday, June 29, 2008 1:06 PM
> To: elecraft at mailman.qth.net
> Subject: Re: [K3] [Elecraft] Transmit AM through FM Filter?
> 
> 
> 
> 
> 
> Dan Atchison wrote:
> > 
> > 
> > 
> > Yeah, I know, it's only $125, but I'm a cheapskate.
> > 
> > 73,
> > Dan -- N3ND
> > 
> > 
> 
> It is not only $125. It is $125. This is a lot of money for 
> something essentially unnecessary to you. That $125 could be 
> much more usefully spent on a better CW filter or if you do 
> not need a CW filter, $125 donated to charity would go a long 
> way to making you feel good compared to knowing your
> rarely sent AM signal is exceptionally clean.
> 
> What do most radios with only 15kHz roofing filters do on AM? 
> 
> 73 Mike
> 
> 
> -- 
> View this message in context: 
> http://www.nabble.com/Transmit-AM-through-FM-Filter--tp1816107
4p18183029.html
Sent from the [K3] mailing list archive at Nabble.com.

_______________________________________________
Elecraft mailing list
Post to: Elecraft at mailman.qth.net
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
 http://mailman.qth.net/mailman/listinfo/elecraft    

Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com