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Analog vs. Digital Front Ends

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N1EU

Analog vs. Digital Front Ends

Sorry, I'm not buying that direct sampling front ends are as prone to
overload as many of the posts are suggesting, especially on 20M and
higher. During the past 3 years, I've worked one CQWW and one ARRLDX
contest from the Northeast with a SteppIR yagi feeding an ANAN-100D with
0dB attenuation and never experienced overload during the weekends. FWIW,
there's a clear indicator on the PowerSDR screen if ADC overload should
ever occur.

The superior rx audio clarity of the direct sampling front end radio is a
game changer to me, although I'm not a fan of computer GUI's. So I'm
looking forward to widespread use of direct sampling front ends by
all-in-one-box hf xcvrs.

73, Barry N1EU
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Jerry Moore

Re: Analog vs. Digital Front Ends

Is it possible your rig has AGC that's keeping strong signals down rather
than the rejection/selection capabilities of your receiver? Just asking.. I
don't know the answer.

-----Original Message-----
From: Elecraft [mailto:[hidden email]] On Behalf Of Barry
N1EU
Sent: Wednesday, September 16, 2015 8:33 AM
To: elecraft
Subject: [Elecraft] Analog vs. Digital Front Ends

Sorry, I'm not buying that direct sampling front ends are as prone to
overload as many of the posts are suggesting, especially on 20M and higher.
During the past 3 years, I've worked one CQWW and one ARRLDX contest from
the Northeast with a SteppIR yagi feeding an ANAN-100D with 0dB attenuation
and never experienced overload during the weekends. FWIW, there's a clear
indicator on the PowerSDR screen if ADC overload should ever occur.

The superior rx audio clarity of the direct sampling front end radio is a
game changer to me, although I'm not a fan of computer GUI's. So I'm
looking forward to widespread use of direct sampling front ends by
all-in-one-box hf xcvrs.

73, Barry N1EU
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N1EU

Re: Analog vs. Digital Front Ends

There's no pre-ADC hardware AGC at work in the radio like there is in the
K3 and Orion.

Barry N1EU

On Wed, Sep 16, 2015 at 8:37 AM, Jerry Moore <[hidden email]> wrote:

> Is it possible your rig has AGC that's keeping strong signals down rather
> than the rejection/selection capabilities of your receiver? Just asking.. I
> don't know the answer.
>
> -----Original Message-----
> From: Elecraft [mailto:[hidden email]] On Behalf Of
> Barry
> N1EU
> Sent: Wednesday, September 16, 2015 8:33 AM
> To: elecraft
> Subject: [Elecraft] Analog vs. Digital Front Ends
>
> Sorry, I'm not buying that direct sampling front ends are as prone to
> overload as many of the posts are suggesting, especially on 20M and higher.
> During the past 3 years, I've worked one CQWW and one ARRLDX contest from
> the Northeast with a SteppIR yagi feeding an ANAN-100D with 0dB attenuation
> and never experienced overload during the weekends. FWIW, there's a clear
> indicator on the PowerSDR screen if ADC overload should ever occur.
>
> The superior rx audio clarity of the direct sampling front end radio is a
> game changer to me, although I'm not a fan of computer GUI's. So I'm
> looking forward to widespread use of direct sampling front ends by
> all-in-one-box hf xcvrs.
>
> 73, Barry N1EU
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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> delivered to [hidden email]
>
>

Rick Stealey

Re: Analog vs. Digital Front Ends

In reply to this post by N1EU

Barry says:
>During the past 3 years, I've worked one CQWW and one ARRLDX
> contest from the Northeast with a SteppIR yagi feeding an ANAN-100D with
> 0dB attenuation and never experienced overload during the weekends.

And Joe presented a very useful tabulation showing how signals combine.
One thing that we should keep in mind is that single band antennas like Steppirs, single band dipoles, etc. greatly attenuate out of band signals. And from Joe's data look what a difference 10-20 db can make. This might be a good case against 80/40 fan dipoles and trap tribanders.
Rick K2XT
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ae4pb

Re: Analog vs. Digital Front Ends

In reply to this post by N1EU

Yes but it still has the equivalent. It's just integrated rather than being
separate. That doesn't make it better or worse, it just lowers the component
count.

-----Original Message-----
From: Elecraft [mailto:[hidden email]] On Behalf Of Barry
N1EU
Sent: Wednesday, September 16, 2015 8:42 AM
To: elecraft
Subject: Re: [Elecraft] Analog vs. Digital Front Ends

There's no pre-ADC hardware AGC at work in the radio like there is in the
K3 and Orion.

Barry N1EU

On Wed, Sep 16, 2015 at 8:37 AM, Jerry Moore <[hidden email]> wrote:

> Is it possible your rig has AGC that's keeping strong signals down
> rather than the rejection/selection capabilities of your receiver?
> Just asking.. I don't know the answer.
>
> -----Original Message-----
> From: Elecraft [mailto:[hidden email]] On Behalf Of
> Barry N1EU
> Sent: Wednesday, September 16, 2015 8:33 AM
> To: elecraft
> Subject: [Elecraft] Analog vs. Digital Front Ends
>
> Sorry, I'm not buying that direct sampling front ends are as prone to
> overload as many of the posts are suggesting, especially on 20M and

higher.
> During the past 3 years, I've worked one CQWW and one ARRLDX contest
> from the Northeast with a SteppIR yagi feeding an ANAN-100D with 0dB
> attenuation and never experienced overload during the weekends. FWIW,
> there's a clear indicator on the PowerSDR screen if ADC overload should
ever occur.

>
> The superior rx audio clarity of the direct sampling front end radio
> is a game changer to me, although I'm not a fan of computer GUI's. So
> I'm looking forward to widespread use of direct sampling front ends by
> all-in-one-box hf xcvrs.
>
> 73, Barry N1EU
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net Please help support this email
> list: http://www.qsl.net/donate.html Message delivered to
> [hidden email]
>
>

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N1EU

Re: Analog vs. Digital Front Ends

In reply to this post by Rick Stealey

All the serious direct sampling ham xcvrs have single band pass filters
ahead of the ADC for ham band reception so that's not an issue.

Barry N1EU

On Wed, Sep 16, 2015 at 9:13 AM, Rick Stealey <[hidden email]> wrote:

> Barry says:
> >During the past 3 years, I've worked one CQWW and one ARRLDX
> > contest from the Northeast with a SteppIR yagi feeding an ANAN-100D with
> > 0dB attenuation and never experienced overload during the weekends.
>
> And Joe presented a very useful tabulation showing how signals combine.
> One thing that we should keep in mind is that single band antennas like
> Steppirs, single band dipoles, etc. greatly attenuate out of band signals.
> And from Joe's data look what a difference 10-20 db can make. This might
> be a good case against 80/40 fan dipoles and trap tribanders.
> Rick K2XT
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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Joe Subich, W4TV-4

Re: Analog vs. Digital Front Ends

On 9/16/2015 9:16 AM, Barry N1EU wrote:
> All the serious direct sampling ham xcvrs have single band pass filters
> ahead of the ADC for ham band reception so that's not an issue.

Not true - the Flex-6300 has no preselectors. Even if the transceiver
includes preselectors (bandpass filters), defining a second "slice
receiver" on a different band causes the preselector to be bypassed.
The preselector (most of which are not very "tight") only works when
operations are confined to a single band.

Those who live in RF quiet locations - no nearby neighbors, no MF or
HF broadcast, etc. - can get away with current direct sampling SDRs
just like those in quiet locations can get away with an IC-706 or 7000.
The *real performance* of the direct sampling technology is equivalent
to a moderate performance conventional transceiver with broadband IF
panadapter.

73,

... Joe, W4TV
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N1EU

Re: Analog vs. Digital Front Ends

You're right about the 6300 Joe. I don't consider the Flex 6300 as
"serious" in terms of a serious contesting radio. I would expect a serious
contester to go with the Flex 6500/6700 or ANAN 100 or 200 series.

On a crowded band being pounded by strong signals, the direct sampling ANAN
rx sounds cleaner to my ears than the K3 or Orion. I don't see the
overload issues hypothesized by many on this thread. But maybe I'm wrong.

The K3 and Orion are ergonomically superior contesting radios however.

Barry N1EU

On Wed, Sep 16, 2015 at 10:27 AM, Joe Subich, W4TV <[hidden email]> wrote:

>
> On 9/16/2015 9:16 AM, Barry N1EU wrote:
>
>> All the serious direct sampling ham xcvrs have single band pass filters
>> ahead of the ADC for ham band reception so that's not an issue.
>>
>
> Not true - the Flex-6300 has no preselectors. Even if the transceiver
> includes preselectors (bandpass filters), defining a second "slice
> receiver" on a different band causes the preselector to be bypassed.
> The preselector (most of which are not very "tight") only works when
> operations are confined to a single band.
>
> Those who live in RF quiet locations - no nearby neighbors, no MF or
> HF broadcast, etc. - can get away with current direct sampling SDRs
> just like those in quiet locations can get away with an IC-706 or 7000.
> The *real performance* of the direct sampling technology is equivalent
> to a moderate performance conventional transceiver with broadband IF
> panadapter.
>
> 73,
>
> ... Joe, W4TV
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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>
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>

Wes (N7WS)

Re: Analog vs. Digital Front Ends

In reply to this post by Rick Stealey

I'm having a hard time understanding where the frequency selectivity of a piece
of wire comes from.

On 9/16/2015 6:13 AM, Rick Stealey wrote:
> And Joe presented a very useful tabulation showing how signals combine.
> One thing that we should keep in mind is that single band antennas like Steppirs, single band dipoles, etc. greatly attenuate out of band signals. And from Joe's data look what a difference 10-20 db can make. This might be a good case against 80/40 fan dipoles and trap tribanders.
> Rick K2XT
> _____________

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Guy Olinger K2AV

Re: Analog vs. Digital Front Ends

In reply to this post by Rick Stealey

In the late 60's W4BVV put a full size 3 el 40m yagi on a 70 foot boom up
150 feet. This would qualify as a passive front end. Pointed at Europe, at
the shack end of coax, peak to peak RF on a scope would measure five to ten
volts when the band was open.

What will today's direct samplers do with 10 volts RF in band on the
antenna terminal?

73, Guy K2AV

On Wednesday, September 16, 2015, Rick Stealey <[hidden email]> wrote:

> Barry says:
> >During the past 3 years, I've worked one CQWW and one ARRLDX
> > contest from the Northeast with a SteppIR yagi feeding an ANAN-100D with
> > 0dB attenuation and never experienced overload during the weekends.
>
> And Joe presented a very useful tabulation showing how signals combine.
> One thing that we should keep in mind is that single band antennas like
> Steppirs, single band dipoles, etc. greatly attenuate out of band signals.
> And from Joe's data look what a difference 10-20 db can make. This might
> be a good case against 80/40 fan dipoles and trap tribanders.
> Rick K2XT
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email] <javascript:;>
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email] <javascript:;>
>

--
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riese-k3djc

Re: Analog vs. Digital Front Ends

In reply to this post by N1EU

http://www.radio-electronics.com/info/antennas/basics/resonance.php

BOB k3djc
On Wed, 16 Sep 2015 08:21:03 -0700 "Wes (N7WS)" <[hidden email]>
writes:

> I'm having a hard time understanding where the frequency selectivity
> of a piece
> of wire comes from.
>
> On 9/16/2015 6:13 AM, Rick Stealey wrote:
> > And Joe presented a very useful tabulation showing how signals
> combine.
> > One thing that we should keep in mind is that single band antennas
> like Steppirs, single band dipoles, etc. greatly attenuate out of
> band signals. And from Joe's data look what a difference 10-20 db
> can make. This might be a good case against 80/40 fan dipoles and
> trap tribanders.
> > Rick K2XT
> > _____________
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]
>

Rick Stealey

Re: Analog vs. Digital Front Ends

In reply to this post by Wes (N7WS)

If I'm using my 40 m dipole and go to 80 meters the signals will jump up SIGNIFICANTLY if I switch to my 80 meter antenna. Several S units.
Same on 20.
So, if instead of a single band 40 m dipole I had a 80/40 fan dipole, wouldn't an SDR have to deal with stronger signals in total?
Same as if we were talking about a Steppir vs a trapped tribander on 10-20 meters.

Rick K2XT

> To: [hidden email]
> From: [hidden email]
> Date: Wed, 16 Sep 2015 08:21:03 -0700
> Subject: Re: [Elecraft] Analog vs. Digital Front Ends
>
> I'm having a hard time understanding where the frequency selectivity of a piece
> of wire comes from.
>
> On 9/16/2015 6:13 AM, Rick Stealey wrote:
> > And Joe presented a very useful tabulation showing how signals combine.
> > One thing that we should keep in mind is that single band antennas like Steppirs, single band dipoles, etc. greatly attenuate out of band signals. And from Joe's data look what a difference 10-20 db can make. This might be a good case against 80/40 fan dipoles and trap tribanders.
> > Rick K2XT
> > _____________
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]

Wes (N7WS)

Re: Analog vs. Digital Front Ends

You're talking about matching, not any frequency selectivity of the wire.
Thousands of guys swear by a so-called G5RV and 43' verticals (I'm not one of
them), antennas that aren't resonant on any ham band where they're used. There
is absolutely no requirement that a wire be resonant to operate efficiently;
especially on receive, which is the case at hand. Any frequency selectivity is
due to the matching network, not anything inherent in the piece of wire.

On 9/16/2015 12:19 PM, Rick Stealey wrote:

> If I'm using my 40 m dipole and go to 80 meters the signals will jump up SIGNIFICANTLY if I switch to my 80 meter antenna. Several S units.
> Same on 20.
> So, if instead of a single band 40 m dipole I had a 80/40 fan dipole, wouldn't an SDR have to deal with stronger signals in total?
> Same as if we were talking about a Steppir vs a trapped tribander on 10-20 meters.
>
> Rick K2XT
>
>> To:[hidden email]
>> From:[hidden email]
>> Date: Wed, 16 Sep 2015 08:21:03 -0700
>> Subject: Re: [Elecraft] Analog vs. Digital Front Ends
>>
>> I'm having a hard time understanding where the frequency selectivity of a piece
>> of wire comes from.
>>
>> On 9/16/2015 6:13 AM, Rick Stealey wrote:
>>> And Joe presented a very useful tabulation showing how signals combine.
>>> One thing that we should keep in mind is that single band antennas like Steppirs, single band dipoles, etc. greatly attenuate out of band signals. And from Joe's data look what a difference 10-20 db can make. This might be a good case against 80/40 fan dipoles and trap tribanders.
>>> Rick K2XT
>>>