[Elecraft] softrock with K3

[Jerry Flanders]

Lyle, perhaps you have actually hooked up the softrock "panadaptor" 
and found a problem. If so, let us know.

Otherwise, considering that the K3 is using a roofing filter which 
should be VERY effective in eliminating any feedthrough from the 
softrock's actual LO freq, until somebody actually hooks one up to 
the K3 and finds a problem, I continue to hope that no isolation is 
required, or that a simple attenuation pad can do the job without 
excessive attenuation of the display sigs.

With the standard K3 softrock panadaptor kit that KB9YIG provides, 
the LO is at 8.191 kHz and K3 IF is at 8.215, 24 KHz away. The 
roofing filters should provide pretty good attenuation at that 
"distance". Some phase noise will be present at 8.215, but it may or 
may not be negligible.

I will definitely use the panadaptor with the K3 I have on order, and 
already have the softrock kit awaiting the build.

Jerry W4UK

At 04:51 PM 12/23/2007, Don Wilhelm wrote:
>Dave,
>
>"simple" and "effective" are often antonyms and do not occur 
>together except in the most simple cases.  Assuring that no signals 
>are inadvertently injected into the K3 IF OUT jack does not sound 
>like a simple case.  Bite the bullet and do a good job of isolating 
>no matter what you use - the performance of your K3 depends on 
>it.  Directly connecting an $11 piece of equipment to a $1000 piece 
>of equipment and expecting no adverse consequences is a lot to be expected.
>It *can* be done - the devil is in the details.
>
>73,
>Don W3FPR
>
>Dave Martin wrote:
>>We'll have to get some ideas for a simple buffer that will provide
>>good isolation.  Otherwise before long questions will be popping up
>>about spurious responses and noise with our new K3s.
>>
>>
>>On Dec 23, 2007 2:19 PM, Lyle Johnson <kk7p at wavecable.com> wrote:
>>
>>>>Any one have any experience with the softrock and the K3...
>>>>
>>>PLEASE remember that you *must* have a high-reverse isolation buffer
>>>between the K3 IF OUT jack and the Softrock antenna input.  The Softrock
>>>may have a huge spur at its carrier frequency and its mixer may not
>>>suppress this adequately.  So there is a potential coupling problem
>>>(mixer) and radiation problem (shielding).  The IF out of the K3 does
>>>not have high reverse isolation characteristics, so you need to ensure
>>>you do not couple a signal at the IF *into* the K3 through this connector.
>>>
>>>73,
>>>
>>>Lyle KK7P