I am using the Flag as brewed by a friends of mine (N0DL and KE0EPY). I am
using it with a Yaesu FT-818 and the DXE preamp. It has proven to be a great
asset in my current issue. The DXE preamp is a very easy to use/polished
product.
I am sure a SpecAn would provide even more revealing results. I am anxious to
see the results of the effort.
73,
Joe kk0sd
-----Original Message-----
From: RFI <rfi-bounces+gary_mayfield=hotmail.com@contesting.com> On Behalf Of
Dave Cole
Sent: Monday, April 12, 2021 8:15 PM
To: rfi@contesting.com
Subject: Re: [RFI] Flag Pennant loop - Tiny SA use
Hi Don,
I may just break down and buy the DXE product! :) Thanks for sharing that
info.
73, and thanks,
Dave (NK7Z)
https://www.nk7z.net
ARRL Volunteer Examiner
ARRL Technical Specialist, RFI
ARRL Asst. Director, NW Division, Technical Resources
On 4/12/21 6:03 PM, Don Kirk wrote:
> Hi Lee,
>
> I've gotten a little lost in this thread, but if you intend to use the
> tinySA with the Portable Flag I would like to comment about the
> placement of the attenuators relative to a preamp. I was involved
> with the initial field testing of the DX Engineering preamp designed
> for use with my portable flag and the first thing I recognized was
> that having attenuation before the preamp really destroyed the signal
> to noise ratio because the signal is so low from the portable flag and
> attenuating it causes the preamp noise figure to become a more
> dominate factor that degrades the signal to noise ratio. The design
> was then changed so that the attenuators come after the preamp which
> fixed the problem by keeping the signal from the portable flag going
> into the preamp as high as possible. The beauty of the DX Engineering
> preamp is that it can be turned off if not needed, and the attenuators
> can be used with the preamp on or off which provides a lot of
> flexibility to handle all situations, and it also has a selectable high pass
> filter to block the AM broadcast band as needed.
>
> Just some things to consider when home brewing your own system if you
> plan to use it with the portable flag that has very negative gain.
>
> Just FYI,
> Don (wd8dsb)
>
> On Mon, Apr 12, 2021 at 8:33 PM Lee STRAHAN <k7tjr@msn.com> wrote:
>
>> Hi LEV Dave and the group,
>> Indeed your comment most true. I have decided that a preamp
>> would be the answer for me but to have the attenuator I mentioned in
>> front of the Preamp. If I have large signals making IMD I certainly
>> wont need the extra gain and dynamic range so attenuate it. If the
>> signals are small they will not overload the dynamic range and make
>> IMD generally and the attenuator can be off. . The attenuator in the
>> Tiny SA is a menu item a bit unhandy to reach in the field. And not much dB
>> range.
>> This way the preamp wont have to be a power hog for high level signals.
>> With the tiny SA at about -100 dBm noise floor I am thinking adding a
>> 1 to
>> 2 dB noise figure preamp which will increase the sensitivity without
>> much added noise over the common 18 to 22 dB you mention. Normally in
>> a lab analyzer you can adjust the sweep speed as well as the
>> resolution bandwidth to get a lower noise display. That’s not an
>> option in the tiny SA. So, I will see how this works.
>> Any way appreciate the comment as it definitely deserves some thought. .
>> Lee K7TJR OR
>> From: David Eckhardt <davearea51a@gmail.com>
>> Sent: Monday, April 12, 2021 4:49 PM
>> To: Lee STRAHAN <k7tjr@msn.com>
>> Cc: Dave Cole <dave@nk7z.net>; rfi@contesting.com
>> Subject: Re: [RFI] Flag Pennant loop - Tiny SA use
>>
>> Don't forget the average 'lab' SA has a typical noise figure around
>> 18 to
>> 22 dB. All need a preamp for reasonable sensitivity. Many of the
>> lab instruments today are being marketed with a built-in preamp for
>> this reason. Also, note the dynamic range is degraded by the gain of
>> the preamp. It's generally best to have it present but easily
>> bypassable for that reason.
>>
>> Dave - WØLEV
>>
>> On Mon, Apr 12, 2021 at 8:35 PM Lee STRAHAN <k7tjr@msn.com<mailto:
>> k7tjr@msn.com>> wrote:
>> Hi Dave and group,
>> I find the Tiny SA a little low on sensitivity so I am planning
>> on adding an external 20 dB preamp with an easier to use step
>> attenuator for RFI hunting.
>> I have some other obligations at the moment so I am temporarily using
>> an SI 4732 radio which is also a tiny box with AM.
>> I have the local power company and a wood products manufacturing
>> company working with me on an interesting conducted interference case
>> I will eventually report on here later after more tests.
>> Lee K7TJR OR
>>
>> -----Original Message-----
>> From: RFI <rfi-bounces+k7tjr=msn.com@contesting.com<mailto:
>> msn.com@contesting.com>> On Behalf Of Dave Cole
>> Sent: Monday, April 12, 2021 1:00 PM
>> To: rfi@contesting.com<mailto:rfi@contesting.com>
>> Subject: Re: [RFI] Flag Pennant loop - added benefit of being
>> broadband
>>
>> BTW:
>>
>> I am currently working on setting up a tinySA on the FLAG... Try it,
>> it is really portable. The tinySA will mount right on the support
>> pole for the FLAG. No computer, no SDR, just a box the size of a pack of
>> smokes...
>>
>> 73, and thanks,
>> Dave (NK7Z)
>> https://www.nk7z.net
>> ARRL Volunteer Examiner
>> ARRL Technical Specialist, RFI
>> ARRL Asst. Director, NW Division, Technical Resources
>>
>> _______________________________________________
>> RFI mailing list
>> RFI@contesting.com<mailto:RFI@contesting.com>
>> http://lists.contesting.com/mailman/listinfo/rfi
>>
>>
>> --
>> Dave - WØLEV
>> Just Let Darwin Work
>>
>> _______________________________________________
>> RFI mailing list
>> RFI@contesting.com
>> http://lists.contesting.com/mailman/listinfo/rfi
>>
> _______________________________________________
> RFI mailing list
> RFI@contesting.com
> http://lists.contesting.com/mailman/listinfo/rfi
>
_______________________________________________
RFI mailing list
RFI@contesting.com
http://lists.contesting.com/mailman/listinfo/rfi
_______________________________________________
RFI mailing list
RFI@contesting.com
http://lists.contesting.com/mailman/listinfo/rfi
|