Re: Elecraft K3S / IC-7610 comparison table

Joe Subich, W4TV
 

IIRC, the IC7610 has a bandpass filter ahead of the ADC whereas the 7300
has no BPF.

The 7610 will have the same problem as the 7300 if the close by
transmitter is in band. It will not have the same problem if the close
by transmitter is on another band or outside the BPF for the current
receive band.

This is the issue with direct conversion SDR design that the proponents
of direct conversion do not want to address. Without filtering to
protect the ADC, the direct conversion receiver sees *ALL* RF sources
from DC to light - a couple 50 KW AM broadcast signals will often wipe
out 160 meters, for example, particularly if they are near the top of
the broadcast band where BPFs are not effective.

Flex have tried to address this by using *SEVEN POLE* BPFs in the 6600
for the primary (160/80/40/20/15/10 meter) bands, but their receivers
still have significantly different MDS depending on the preamp in use
(or attenuator).

73,

... Joe, W4TV

On 2018-07-04 10:51 AM, dalej via Groups.Io wrote:
I think the 7610 uses extra band pass filtering ahead of the dsp.
I wouldn’t give up my K3s for one.
73
Dale, k9vuj
On 04, Jul 2018, at 9:42, mikerodgerske5gbc via Groups.Io <mikerodgerske5gbc=yahoo.com@groups.io> wrote:
Does the 7610 suffer the same problems as the 7300 with close by transmitters or have they addressed that?
73
Mike R
7!
Absolutely Awesome
On Jul 4, 2018, at 9:34 AM, dalej via Groups.Io <dalej2=mac.com@groups.io <mailto:dalej2=mac.com@groups.io>> wrote:

When I’ve asked the question blocking dynamic range in other forums they always said the two kinds of receivers can’t be tested the same way :).

Guess that explains it.

Tnx Joe

Dale, K9VUJ




On 04, Jul 2018, at 8:27, Joe Subich, W4TV <lists@... <mailto:lists@...>> wrote:


On 2018-07-04 4:02 AM, dalej via Groups.Io wrote:
I’m interested in this noise power ratio test that some use to
evaluate receivers. How does that fit in with the K3 ?
Noise power testing *can* be extremely confusing when comparing
direct sampling "receivers" like the Flex or IC-7851/7610/7300
with IF based SDR receivers like the K3.

In practice, proponents of noise power testing reduce the noise
power level until the ADC of the direct sampling receiver no
longer goes into overflow and then measure the IMD products
(increase in noise floor in the "notch" region). With IF/filter
based devices the noise power is not reduced. Effectively, the
two receiver technologies are being tested at different signal
levels.

The direct conversion receiver is being tested at maximum
interfering signal level but not maximum sensitivity while
the IF/Filter receiver is being tested at maximum sensitivity.
None of the tested direct conversion SDRs are capable of 100+
dB "dynamic range" while simultaneously maintaining a MDS of
~ -140 dBm unlike a IF/filter receiver (either analog like the
K2 or DSP like the K3/K3S).

73,

... Joe, W4TV


On 2018-07-04 4:02 AM, dalej via Groups.Io wrote:
I’m interested in this noise power ratio test that some use to evaluate receivers. How does that fit in with the K3 ?
Dale, K9VUJ
On 03, Jul 2018, at 21:16, N6KR <n6kr@... <mailto:n6kr@...>> wrote:
In response to many questions fielded by our sales and support staff we’ve put together a comparison of the K3S vs. the IC-7610.
While all rigs have certain strengths, the K3S has a combination of performance, features, and form factor that provide unique benefits to the operator, especially those who may encounter high-signal conditions or require portability (or both, as in the case of Field Day, DXpeditions, etc.).
The comparison table is in draft form and will continue to evolve, so we’re not posting it on our website just yet. However, we’ll be happy to send the current edition on request to anyone actively weighing the tradeoffs between the K3S and other transceivers.
Please email me directly if you’re interested. I’ll be happy to expand on information presented, whether theoretical or functional. No doubt these discussions will help us refine the table.
73,
Wayne
N6KR





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