[Elecraft] preamp for using an SDR as a pan adapter

Fri Oct 4 21:27:43 EDT 2019

Fred,

Is that "K3S" or multiple "K3"s?
All The K3S have the mod, as well as later K3s.  If an early K3, then 
you may need the mod.

73,
Don W3FPR

On 10/4/2019 8:59 PM, Fred Massey wrote:
> I knew I had an issue when I could hear signals on the K3s that weren’t
> showing on the waterfall.
> 
> I need to engage Elecraft tech support to see if I need the mod for my K3s,
> and see what they say about using an external buffer amp or preamp.
> 
> When I posted, I thought this might be a common problem that others had
> fixed before.
> 
> 
> On Fri, Oct 4, 2019 at 6:59 PM Bob McGraw K4TAX <rmcgraw at blomand.net> wrote:
> 
>> I read that folks have successfully used the Clifton buffer amp.
>> Certainly worth a try.   Others have indicated only about 6 dB of gain is
>> needed.
>>
>> The software I use for my RSP-1 allows RF Gain changes.  Thus with the
>> lower IF output of my K3S, I just raise the gain of the RSP-1 via the
>> software.  I've never considered the SDR receivers of that type to be very
>> precise with regard to "calibration".    Although some seem to think they
>> can split hairs on a mosquito with the level and frequency accuracy of the
>> receivers.    I do not consider them of instrumentation quality, thus
>> anything +/-10 dB is deemed satisfactory.  Likewise the same with frequency
>> accuracy.  Others may have different experiences with different receivers.
>>
>> 73
>>
>> Bob, K4TAX
>>
>>
>> On 10/4/2019 6:34 PM, Fred Massey wrote:
>>
>> A friend of mine, Tim AB4B, suggested that I might need a buffer amp to
>> keep the IF being pulled down by the sdr. DXEngineering sells the Clifton
>> Z10000.  That adds about 6db of gain, but maybe the buffering that it does
>> has an even bigger effect.
>>
>> On Fri, Oct 4, 2019 at 2:18 PM Bob McGraw K4TAX <rmcgraw at blomand.net>
>> wrote:
>>
>>> In a word, YES.   I find that to be true with my K3S as well as other
>>> brands/models of radios.   Thus you'll need about 20 dB of gain in the
>>> form of a preamp between the IF output and the QSR receiver.
>>>
>>> 73
>>>
>>> Bob, K4TAX
>>>
>>>
>>> On 10/4/2019 12:57 PM, Fred Massey wrote:
>>>> Some.  I was planning on sending an email to Elecraft support with the
>>> s/n
>>>> of my K3s to see if I needed the mod.  The difference I’m seeing in
>>> signal
>>>> strength is about 20+ dB.  Is it normal for the if-out to be weaker
>>> than a
>>>> direct connection to the antenna?
>>>> 73,
>>>> Fred
>>>> AE4ED
>>>>
>>>> On Fri, Oct 4, 2019 at 12:44 PM Don Wilhelm <donwilh at embarqmail.com>
>>> wrote:
>>>>
>>>>> Fred,
>>>>>
>>>>> Have you looked the K3 IF Output mod?
>>>>>
>>>>>
>>> https://ftp.elecraft.com/K3/Mod%20Notes%20Alerts/IF_Output_Buffer_Gain_Mod_Rev_A.pdf
>>>>>
>>>>> If you don't have the 13k SMD resistor or a 1/8 watt 13k resistor, you
>>>>> can order the kit from Elecraft.
>>>>>
>>>>> 73,
>>>>> Don W3FPR
>>>>>
>>>>> On 10/4/2019 1:24 PM, Fred Massey wrote:
>>>>>> Good afternoon Wes and all,
>>>>>>
>>>>>> If I connect the antenna directly to the QSR-1, I get the same signal
>>>>> level
>>>>>> as the K3s.  But, when I connect to the QSR-1 to the IF-out, the
>>> signal
>>>>> is
>>>>>> about 4 s-units less.
>>>>>>
>>>>>> Any ideas...anyone?
>>>>>>
>>>>>> Fred
>>>>>>
>>>>>> On Thu, Oct 3, 2019 at 4:14 PM Wes <wes_n7ws at triconet.org> wrote:
>>>>>>
>>>>>>> I use an SDR-IQ on the i-f output on my (very) early K3S.  it works
>>>>> fine.
>>>>>>> IIRC,
>>>>>>> always a dubious proposition, I did the mod on my original K3 and it
>>>>>>> worked well
>>>>>>> too without any additional amplification.  I think you have another
>>>>>>> problem.
>>>>>>>
>>>>>>> Wes  N7WS
>>>>>>>
>>>>>>> On 10/3/2019 2:01 PM, Fred Massey wrote:
>>>>>>>> Good afternoon,
>>>>>>>>
>>>>>>>> I have successfully connected my QSR-1 to my K3s if-out, and
>>>>> immediately
>>>>>>>> noticed the signal strengths showing on the QSR-1 were much
>>> weaker.  I
>>>>>>>> probably have an early K3s, so the if-out signal strength is even
>>>>> weaker.
>>>>>>>> Any recommendations at a good preamp to use?  It seems like 20db is
>>>>> what
>>>>>>> I
>>>>>>>> need:
>>>>>>>>
>>>>>>>> 73,
>>>>>>>> Fred
>>>>>>>> AE4ED
>>>>>>> ______________________________________________________________
>>>>>>> Elecraft mailing list
>>>>>>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>>>>>>> Help: http://mailman.qth.net/mmfaq.htm
>>>>>>> Post: mailto:Elecraft at mailman.qth.net
>>>>>>>
>>>>>>> This list hosted by: http://www.qsl.net
>>>>>>> Please help support this email list: http://www.qsl.net/donate.html
>>>>>>> Message delivered to fhmassey at gmail.com
>>>>>> ______________________________________________________________
>>>>>> Elecraft mailing list
>>>>>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>>>>>> Help: http://mailman.qth.net/mmfaq.htm
>>>>>> Post: mailto:Elecraft at mailman.qth.net
>>>>>>
>>>>>> This list hosted by: http://www.qsl.net
>>>>>> Please help support this email list: http://www.qsl.net/donate.html
>>>>>> Message delivered to donwilh at embarqmail.com
>>>>>>
>>>> ______________________________________________________________
>>>> Elecraft mailing list
>>>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>>>> Help: http://mailman.qth.net/mmfaq.htm
>>>> Post: mailto:Elecraft at mailman.qth.net
>>>>
>>>> This list hosted by: http://www.qsl.net
>>>> Please help support this email list: http://www.qsl.net/donate.html
>>>> Message delivered to rmcgraw at blomand.net
>>>
>>> ______________________________________________________________
>>> Elecraft mailing list
>>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>>> Help: http://mailman.qth.net/mmfaq.htm
>>> Post: mailto:Elecraft at mailman.qth.net
>>>
>>> This list hosted by: http://www.qsl.net
>>> Please help support this email list: http://www.qsl.net/donate.html
>>> Message delivered to fhmassey at gmail.com
>>
>>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Elecraft at mailman.qth.net
> 
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to donwilh at embarqmail.com
> 