[Elecraft] K3 FM filter required for full AM receive width

[Stewart Baker]

Blast ! you got there before me Dave.
I have been modeling some suitable LC filters, but as you say they 
are a bit wide for transmit. However looking back in my log shows 
that I haven't had an AM QSO for 10's of years, so it's unlikely I 
will have one now. :-)

73
Stewart G3RXQ
On Mon, 5 May 2008 11:01:13 -0400, Dave Martin wrote:
> On 5/5/08, Stewart Baker <stewart at baker.nildram.co.uk> wrote:
>> Why not an LC filter for AM reception instead of an expensive
>> crystal roofing filter ?
>>
> That's what I did.  I cut a scrap of PC board to the size of a 
filter
> and used three toroids with tuning and coupling caps.  It worked 
just
> fine in position one, set up as 13 KHz.  The DSP hasn't suffered 
at
> all.  Maybe with more antenna gain one might see some overload 
from
> nearby signals, but not with my modest wire.  I sure wouldn't 
transmit
> with it, though.  It's hugely wide, offering no attenuation of
> unwanted mixer products.
>
> Dave  W5DHM
> _______________________________________________
> 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