[Elecraft] preamp for using an SDR as a pan adapter
Bob McGraw K4TAX
rmcgraw at blomand.net
Fri Oct 4 19:58:57 EDT 2019
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
> <mailto: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 <mailto: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
> <mailto: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
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