[1000mp] MP vs MkV vs K2

Mon, 1 Jul 2002 09:21:33 -0400

> The ARRL has traditionally tested IMD DR (and BDR) using an unwanted
> signal spaced 20 kHz from the desired signal.  Tom, W8JI finally
> convinced them that 5 kHz spacing would be more meaningful, 
> so now they
> include IMD DR and BDR values for both spacings.

I am not sure it was all Tom.  :-) ARRL has been testing the IMD DR of
receivers using 2 to 100 kHz spacing for about the past 10 years. These
results have been being documented in the expanded test result reports. The
recent change was to start reporting the 5 kHz results in the test-result
report column in the Product Reviews.

73, 
Ed Hare, W1RFI
ARRL Lab
225 Main St
Newington, CT 06111
Tel: 860-594-0318
Internet: [email protected]
Web: http://www.arrl.org/tis

> -----Original Message-----
> From: [email protected] [mailto:[email protected]]
> Sent: Saturday, June 29, 2002 10:54 PM
> To: [email protected]
> Subject: Re: [1000mp] MP vs MkV vs K2
> 
> 
> Tom, W7GT wrote:
> 
> "Where are the non-linear products in the MP being generated?  In
> particular, are they in the early stages, prior to the 8.2 and 455 IF
> filters?"
> ----------
> 3rd-order IMD (IMD DR) products are the result of unwanted 
> signals (along
> with the desired signal) getting inside the various filters 
> in a receiver
> and thus producing spurious responses.  In the MP (and most 
> other modern
> receivers), these filters are the "roofing" filter in the 
> early receiver
> stages, the 1st IF xtal filter, and the subsequent IF xtal filter. 
> Because the unwanted signals we talk about when we are 
> referring to IMD
> DR and BDR are normally outside of the IF xtal filters (but inside the
> roofing filter), I would say that 3rd-order IMD "birdies" are 
> most often
> generated in the early stages of the receiver.
> 
> The ARRL has traditionally tested IMD DR (and BDR) using an unwanted
> signal spaced 20 kHz from the desired signal.  Tom, W8JI finally
> convinced them that 5 kHz spacing would be more meaningful, 
> so now they
> include IMD DR and BDR values for both spacings.
> 
> 73, de Earl, K6SE
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