Date   

Re: Si4734 Hardware and Software Guides

sdwillingham
 

Roy,

A clarification: the code in the reference design I linked to
is actually operating the chip in 3-wire mode. It nicely makes
use of the MCU's SPI interface hardware, but the incoming and
outgoing serial data lines are actually connected together with
a 1 kohm resistor (see the schematic in the app note).

I actually used a version of that code example in the first
version of my interface. That said, I'm back to bit-banging
with my current software.

Yesterday, one of these arrived at my house from Mouser:

http://www.silabs.com/Support%20Documents/TechnicalDocs/ToolStick_F321_DC_UG.pdf

It's quite a lot bigger than my present prototype, but should be
easier to work with in terms of solder points, etc. Last night
I determined that if I cut off the bottom third of the board
(where the potentiometer and switch are), I will be able to fit
the remainder inside my PL-380. (These Tecsuns are remarkable
in their packaging design -- very little wasted space and yet
very easy to dis- and re-assemble.) The PL-380's built-in USB
connector will make this a very stealth modification!

-Scott-

--- In ultralightdx@..., "Roy" <roy.dyball@...> wrote:

Because the Tecsun uses the 3 wire interface I feel it is best to stick
with it while they use it because I can unhook my interface, and as soon
as I switch the local MCU control lines back in it takes over without a
fuss and you can still use any changes you have made until power down
while using the radio normally.

I am really leaning toward using an MCU like you are doing and am
looking forward to seeing your final results. I noticed you have posted
more pictures and your radio with interface looks good now it is back
together.


Re: conditions last night

jim_kr1s <jkearman@...>
 


--- In ultralightdx@..., Allen Willie >
>
> Last night here in the North Atlantic produced a TA opening which was later than usual here ( about 1:30 AM Local 5:00 UTC ) Was hoping to ride the wave longer but the sandman took over .

Allen,

Strong coffee! :)  Good results there. The aurora is really kicking up, and the geomagnetic field is disturbed today.

http://sec.noaa.gov/pmap/pmapN.html


http://geomag.nrcan.gc.ca/common_apps/ssp-1-eng.php

As you're so much farther north than me I'd be interested in how things fare tonight.

Other sources of propagation info at "Propagation" tab here: http://kr1s.kearman.com/

73,

Jim, KR1S
http://qrp.kearman.com/ 


Re: Guy Atkin's Independent Testing of PL-380 7.5" Loopstick

Guy Atkins
 



Hi Roy,
 
I really appreciate the clear fashion in which you (and Scott) explain the SiLabs chip's operation! You are correct; I did not realize that the chip tunes for proper inductance after it detects a change of frequency; I thought it "senses" the inductance continuously, and displays any signal strength changes during the "refresh" cycle of the RSSI indicator.
 
I'd forgotten about the maxim of best "Q" with a centered coil. After so many years of seeing stock loopsticks with factory coils positioned so far from center, I've not given it much thought. I like Scott's idea of starting coil winding right at the center, and seeing if there's any difference between a 330 uH and 550 uH coil.
 
The purpose of the black arrow marker in my video was simply to show the positioning of the coil for which I had previously found to give the best reception. With that precise point in mind it was easier to see and hear the signal fall-off when the coil was shifted. However, I agree that by not retuning the receiver after each shift it becomes a moot point.
 
Despite the flaws in the method, it still remains that I'm seeing a greater than 20 dB improvement over the stock loopstick, and that's excellent. If performance increases further with a coil at the rod's exact center, that will be even better.
 
I'm knee-deep in finalizing Wellbrook arrays and QDFA phased array antennas plus other preparations for a coastal DXpedition later this month, so I won't be able to return to ULR radio experimentation for a while. However, I'm sure Gary and others will be able to follow up on your and Scott's suggestions soon. I look forward to reading about these experiments of others.
 
73,
 
Guy Atkins
Puyallup, WA USA
 
 
 
On Tue, Feb 2, 2010 at 2:13 AM, <ultralightdx@...> wrote:

 
13e.

Re: Guy Atkin's Independent Testing of PL-380 7.5" Loopstick

Posted by: "Roy" roy.dyball@...   roy.dyball

Tue Feb 2, 2010 12:56 am (PST)




Hi Garry

Looking at the video of the coil being moved indicates that the all that
is happening is that you are moving the coil away from a peak that has
already been established from a previous tuning operation that has set
the varactors capacitance to tune the loopstick at the black mark for
the coils inductance at that position on the rod. It appears to me that
the coil was originally tuned at the black mark then moved off peak
before the video started.

You cannot expect the Si4734 to track while moving the coil because it
does not know the coil has moved and keeps the capacitance unchanged,
but you have changed the inductance by moving the coil and of course the
signal will rises and fall when you move the loopstick.

Had the radio been retuned each time the coil was moved the Si4734 would
have returned its varactor capacitance for the new inductance brought
about by the movement and really the signal would not have changed by
much more than about 3dbu across the rod.

The only time the Si4734 changes its capacitance to match the loopsticks
inductance is during a tuning operation and this was not done in the
video. The capacitance does not change automatically when you slide the
coil. The whole idea of the Si4734 is it is self aligning. And that is
why you must step off and step back on frequency every time you move the
loopstick.

It would be very interesting to see the video redone showing the method
described above because every time the coil was moved and the frequency
retuned the audio and the signal levels (within about 3dbu) would have
come back up.

We must understand how this chip works and use this chip as it is
designed and not copy old methods from completely different technology
without applying them to this new technology correctly.

I think there has been a misunderstanding as to the correct operation of
how the Si4734 works and I now that criticism can be taken the wrong way
especially when someone has put a lot of work into their results and
presented them sincerely.

I really believe that the video showing a peak signal on the rod is
incorrectly presented and had the radio been retuned between movements
it would have only shown how cleaver the Si4734 really is at realigning
itself and not a signal dropping off from an established peak.

Cheers Roy.



conditions last night

Allen Willie
 

 
 
Hi Guys,
 
Last night here in the North Atlantic produced a TA opening which was later than usual here ( about 1:30 AM Local 5:00 UTC ) Was hoping to ride the wave longer but the sandman took over .
 
1476 khz -  Euskadi Irratia , Biribilondo Spain  5:32 UTC 2/2/10 - News by man  in Basque or Spanish  (strongest signal I've ever heard from this one )
 
 
Other logs earlier in the evening
 
1150 khz - CHGM - Gaspe, Quebec  00:27 UTC 2/2/10 w/ french talk and many Country music tunes in English and french  (sounded like a local )
 
 720 khz - KNR - Simmutaq, Greenland   00:50 UTC 2/2/10 w/ musical selections and woman reading in Danish or Greenlandic (Great signal from this one tonight )
 
 
Good DX to All
 
Allen Willie
St. John's, Newfoundland  37:47N  52:45W
SRF-39 FP barefoot
 
 


Yahoo! Canada Toolbar : Search from anywhere on the web and bookmark your favourite sites. Download it now!


Re: I received my PL-380 today but don´t know

www-clorofila-up-to@...
 

Hi Neil,

Thanks for your return.

The merit goes to Jim and Gary because the too important photos that clarify once and for all any doubt about the identification of PL-380´s newest version.

Milton

Brasil

 

 

Re: [ultralightdx] Re: I received my PL-380 today but don´t know

Posted by: "Neil Findlay" neil.findlay52@... neil.findlay52

Tue Feb 2, 2010 4:53 am (PST)



Thanks

I had not found till I saw your Photograph

Looked an still could not see it -- opened other end that was still taped up and there it was

So mine is a 2009 version 1

Thanks again

Neil Findlay

 


Traverse City, MI Loggings, All Times UTC

Antonios Kekalos <akekalos@...>
 

2.2.10, 0529, am 1660, WQLR, Kalamazoo, MI, 175mi/281km, Sony SRF-M37V (The Fan)
2.2.10, 1350, am 1680, WPRR, Grand Rapids, MI, 127mi/204km, Sony SRF-M37V (Public Reality Radio)

--
Tony Kekalos
Traverse City, MI
SWLR-RN072
EN74es



Re: Si4734 Hardware and Software Guides

gratiscomputer <gratiscomputer@...>
 

Roy schreef:

Hi Marc

Yes I came across that site. They had written their code in VB6 and were using the I2C interface to control the chip. They openly admitted it did not work properly and someone had
I threw away my history in firefox, which was a stupid idea... Do you have the site??

Delphi is Pascal code and is much clearer than all those VB/C++/C# samples..
http://freepascal.org will supply a pascal compiler for all platforms...


Marc


Re: I received my PL-380 today but don´t know if it´s the late...

neil.findlay52
 

Thanks
 
I had not found till I saw your Photograph
 
Looked an still could not see it -- opened other end that was still taped up and there it was

So mine is a 2009 version 1
 
Thanks again
 
Neil Findlay
 


From: jim_kr1s <jkearman@...>
To: ultralightdx@...
Sent: Tue, 2 February, 2010 1:02:36 AM
Subject: [ultralightdx] Re: I received my PL-380 today but don´t know if it´s the late...

 


--- In ultralightdx@ yahoogroups. com, "Silvio" wrote:

> According Jim´s answer (which also grateful for the answer) I sniffed that he he did not know about the details of this so relevante label with this inscription.

Hi, Milton,

My eyes are going. I found the numbers on the end of the flap. I put a photo with a ring around the version number in the Photos section of our Yahoo site, in an album titled "PL-380 Version." This link to it might work:

http://groups. yahoo.com/ group/ultralight dx/photos/ album/1244091616 /pic/list

73,

Jim, KR1S
http://qrp.kearman. com/ 



Yahoo!7: Catch-up on your favourite Channel 7 TV shows easily, legally, and for free at PLUS7. Check it out.


Re: Si4734 Hardware and Software Guides

Roy <roy.dyball@...>
 

Hi Marc

Yes I came across that site. They had written their code in VB6 and were using the I2C interface to control the chip. They openly admitted it did not work properly and someone had rewritten the program using Delphi which is what they are using now.

Cheers Roy.   

--- In ultralightdx@..., gratiscomputer wrote:
>
> Roy schreef:
> >
> >
> > Hi Scott
> >
> > Thank you for the link to the sample C code and the explanation. All
> > my code is written in VB.NET 2008. I have many years experience with
> > it from my previous business dealings before I retired and the program
> > was going before I thought too much about it. I have got the 3 wire
> > interface running really well and the 9 bit data word was a real
> > challenge especially in VB.NET, I think the hardest part was getting
> > the half clock cycle delay correct during the bus turn around.
> >
>
> Strange, but I think I saw some source code on the german site modul-bus
> ag (or so), where they sell a silabs chip on a usb-bridge.
>
> Marc
>


Re: I received my PL-380 today but don´t know if it´s the late...

Silvio <www-clorofila-up-to@...>
 

Hi Jim, Hi Gary !

Thanks both for the highly useful and enlightening photos and explantions about soft mute & SW stability !

Unfortunately my Pl-380 is old version.

Because my english is basic (many times with google´s help) i did not understand the meaning of the word "flap" and only with the box´s flap photo i could do it.

So since the soft mute did not change, I'll give it time before making a possible exchange or acquisition of a new version.

I am very grateful for clarification and follow my wishes of great 73's for everyone.

Maybe my question is that of many people because with respect to SW, I am thinking about creating a port for an external antenna to SW to pull a wire from the battery negative and another from telescopic antenna. I did this with the Tecsun R9012 that I had and the improvement was remarkable. I think there would be no problem in the case of PL-380. Although i'm more focused on Dxer in OM, i thik to do this procedure.

Milton
Brasil


In ultralightdx@..., "jim_kr1s" <jkearman@...> wrote:


--- In ultralightdx@..., "Silvio" <www-clorofila-up-to@>
wrote:

According Jim´s answer (which also grateful for the answer) I
sniffed that he he did not know about the details of this so relevante
label with this inscription.

Hi, Milton,

My eyes are going. I found the numbers on the end of the flap. I put a
photo with a ring around the version number in the Photos section of our
Yahoo site, in an album titled "PL-380 Version." This link to it might
work:

http://groups.yahoo.com/group/ultralightdx/photos/album/1244091616/pic/l\;
ist
<http://groups.yahoo.com/group/ultralightdx/photos/album/1244091616/pic/\;
list>

73,

Jim, KR1S
http://qrp.kearman.com/ <http://qrp.kearman.com/>
Re: [ultralightdx] Re: I received my PL-380 today but don´t know
Posted by: "D1028Gary@..." D1028Gary@... dxergary
Mon Feb 1, 2010 5:35 pm (PST)


Hi Milton,

Thank you for your kind comments, which are much appreciated.

My earlier photo of the Tecsun PL-380 model shipping boxes was not so
clear, so here is a better one. You can easily see the writing "2009.9 VER.2"
and "2009.9 VER.1" on the shipping box flaps in the photo below, which can
help any DXer determine whether or not the model is a "new version" or old
version" PL-380. This same photo is posted at
_http://www.mediafire.com/?nimoyajwkzj_ (http://www.mediafire.com/?nimoyajwkzj) , for those who cannot
receive the photo in their email.

Regarding the soft-mute issue, Milton, I have tested both the "new version"
and "old version" PL-380 models by tuning 1 kHz up or down (as Scott has
recommended), but I cannot detect any difference in the soft-mute function.
I think that the soft-mute function is set at the same level on both of the
PL-380 versions, but this level is significantly lower than on the PL-310,
D96L or other Si4734 models.

Milton, the SW band on the PL-380 is usually stable on all models, both new
and old version. When I was drafting the PL-380 review one of my two
review models had a defective SW section with an intermittent oscillation
problem, but this was only a problem in one out of twelve PL-380 models so far,
so it seems that this was just a rare issue. Seven other "old version"
PL-380 models have been fine on the SW band.
***


Re: Si4734 Hardware and Software Guides

gratiscomputer <gratiscomputer@...>
 

Roy schreef:

Hi Scott

Thank you for the link to the sample C code and the explanation. All my code is written in VB.NET 2008. I have many years experience with it from my previous business dealings before I retired and the program was going before I thought too much about it. I have got the 3 wire interface running really well and the 9 bit data word was a real challenge especially in VB.NET, I think the hardest part was getting the half clock cycle delay correct during the bus turn around.
Strange, but I think I saw some source code on the german site modul-bus ag (or so), where they sell a silabs chip on a usb-bridge.

Marc


Re: Si4734 Hardware and Software Guides

Roy <roy.dyball@...>
 

Hi Phil

I would gladly do that for you but my G8 with the interface has the Si4734 removed at the moment. I will be able to do it toward the end of the week when the new chip arrives and I have installed it.

When you tune a SW frequency you change the 0 high and low byte capacitance values signifying automatic tunning at MW frequencies, to a 1 in the low byte and a 0 in the high byte capacitance value signifying SW. I can't remember what it comes back with for SW frequencies but I will let you know as soon as it is running again.

Roy.

--- In ultralightdx@..., "just_rtfm" wrote:
>
>
>
> Roy, thanks for your informative post! if you have time: tune your G8 to 5 MHz via the radio and then poll status via your USB interface, what is the capacitor value? how about at 10 MHz? 20 MHz?
>
> Scott, thanks for the ZIP... lots of great info in there.
>
> regards,
> phil :)
>


Re: Si4734 Hardware and Software Guides

Roy <roy.dyball@...>
 

Hi Scott

Thank you for the link to the sample C code and the explanation. All my code is written in VB.NET 2008. I have many years experience with it from my previous business dealings before I retired and the program was going before I thought too much about it. I have got the 3 wire interface running really well and the 9 bit data word was a real challenge especially in VB.NET, I think the hardest part was getting the half clock cycle delay correct during the bus turn around.

Because the Tecsun uses the 3 wire interface I feel it is best to stick with it while they use it because I can unhook my interface, and as soon as I switch the local MCU control lines back in it takes over without a fuss and you can still use any changes you have made until power down while using the radio normally.

I am really leaning toward using an MCU like you are doing and am looking forward to seeing your final results. I noticed you have posted more pictures and your radio with interface looks good now it is back together.

Cheers Roy.

--- In ultralightdx@..., "sdwillingham" wrote:
>
>
>
>
> Roy,
>
> The 9-bit control word is a bit of a pain, but although it is not
> obvious, it is not too hard to use a standard 8-bit SPI-type
> interface to communicate with the Si4734. The technique is used
> in this software:
>
> http://www.silabs.com/Support%20Documents/Software/AN264SW.zip
>
> (See the CONTROL_WRITE and CONTROL_READ macros in file
> F320_Si470x_Interface.h. Note, this code is for the Si470x parts,
> but works the same for Si473x if you change the chip-address to
> 0xA0 instead of 0x60.)
>
> The basic idea is to do a 2-byte read or write by packaging the
> 25-bit command+response or command+data in four 8-bit transactions.
> (While manually banging the SENB signal before and after the
> 32-bits.) The first 25 bits are as documented for the part. The
> last 7 bits just hang on as partial extra response or data. When
> SENB is driven high, the last partial transaction is aborted and
> the control interface state-machine is reset for a new transaction.
>
> Perhaps you can simplify your interface with this technique.
>
> Cheers,
> Scott
>
> --- In ultralightdx@..., "Roy" roy.dyball@ wrote:
> > The 3 wire (SDIO SCLK SEN) control interface opened up a big can of
> > worms because it uses a non standard nine bit control word. I then
> > discovered I could use the advanced bit banging functions of the FTDI
> > chip to construct a non standard nine bit word and get my I/O routines
> > running fast enough to produce good results. By this time it was clear
> > to me that RS-232 would not do the job.
>


Re: Si4734 Hardware and Software Guides

just_rtfm
 

Roy, thanks for your informative post! if you have time: tune your G8 to 5 MHz via the radio and then poll status via your USB interface, what is the capacitor value? how about at 10 MHz? 20 MHz?

Scott, thanks for the ZIP... lots of great info in there.

regards,
phil :)


Re: Guy Atkin's Independent Testing of PL-380 7.5" Loopstick

Roy <roy.dyball@...>
 

Hi Garry

Looking at the video of the coil being moved indicates that the all that is happening is that you are moving the coil away from a peak that has already been established from a previous tuning operation that has set the varactors capacitance to tune the loopstick at the black mark for the coils inductance at that position on the rod. It appears to me that the coil was originally tuned at the black mark then moved off peak before the video started.

You cannot expect the Si4734 to track while moving the coil because it does not know the coil has moved and keeps the capacitance unchanged, but you have changed the inductance by moving the coil and of course the signal will rises and fall when you move the loopstick.

Had the radio been retuned each time the coil was moved the Si4734 would have returned its varactor capacitance for the new inductance brought about by the movement and really the signal would not have changed by much more than about 3dbu across the rod.

The only time the Si4734 changes its capacitance to match the loopsticks inductance is during a tuning operation and this was not done in the video. The capacitance does not change automatically when you slide the coil. The whole idea of the Si4734 is it is self aligning. And that is why you must step off and step back on frequency every time you move the loopstick.

It would be very interesting to see the video redone showing the method described above because every time the coil was moved and the frequency retuned the audio and the signal levels (within about 3dbu) would have come back up.

We must understand how this chip works and use this chip as it is designed and not copy old methods from completely different technology without applying them to this new technology correctly.

I think there has been a misunderstanding as to the correct operation of how the Si4734 works and I now that criticism can be taken the wrong way especially when someone has put a lot of work into their results and presented them sincerely. 

I really believe that the video showing a peak signal on the rod is incorrectly presented and had the radio been retuned between movements it would have only shown how cleaver the Si4734 really is at realigning itself and not a signal dropping off from an established peak.

Cheers Roy. 

 


--- In ultralightdx@..., D1028Gary@... wrote:
>
> Hello All,
>
> This is forwarded from Guy Atkins, who apparently had a problem getting
> this message posted to the Ultralightdx Yahoo site:
>
>
>
>
> .
>
>
> ---------- Forwarded message ----------
> From: Guy Atkins <_dx@..._ (mailto:dx@...) >
> Date: Mon, Feb 1, 2010 at 4:56 PM
> Subject: Modding the Tecsun PL-380 with an External Ferrite Antenna - My
> Experience
> To: _ultralightdx@... (mailto:ultralightdx@...)
>
>
> I've followed some of the recent discussion about modifying the PL-380
> with the Amidon type 61, 7.5" ferrite rod that is commonly used with the
> hotrodded Eton E100 receivers. Having modified Kchibo D96Ls and Eton E100s with
> this useful Amidon item, I decided that it was time to try my hand at the
> Tecsun PL-380.
>
>
> I wasn't sure what to expect regarding the optimum coil inductance and
> position of the coil on the ferrite, since there's been a good amount of
> debate on this topic. Gary DeBock claims an inductance around 554 uH is the best
> for all MW frequencies, and that there's a "sweet spot" on the rod where
> an 81 turn coil of 40/44 Litz wire provides this inductance, giving the
> strongest signals across the band with this fixed position coil.
>
>
> The SiLab Si4734 chip's datasheet indicates an acceptable 180-450 uH
> inductance range for the antenna, and the chip tunes a varactor capacitor for
> best performance on each MW frequency (resonating the LC circuit)... no
> manual adjustments at the factory are needed. For the ULR experimenter this
> means there should be NO "best" position (sweet spot) of a coil on the external
> Amidon ferrite rod, as long as the inductance is within 180-450 uH.
>
>
> I dove into the disassembly of my PL-380, very curious as to what I would
> find gives the best signal gain with an Amidon rod modified receiver. Maybe
> there's be no difference 180 to 450 uH, just as SiLabs' data implies.
>
>
> I removed the small, flat ferrite antenna from the PL-380 and found it
> measured 239 uH, clearly within the specified range.
>
>
> An 81 turn Litz wire coil (the recommended 40/44 style) with Amidon 7.5"
> type 61 rod was tried next, mounted externally with the "piece of a
> carpenters level" trick that Gary pioneered as a simple frame to support a slider
> coil antenna.
>
>
> It was quickly evident that Gary is correct--there *is* a "best"
> inductance for the PL-380, and it is far outside the range given in the SiLabs
> chip's documentation. I listened to low, mid, and high-band MW stations for an
> audible peak and kept a close watch on the RSSI signal numbers on the
> radio's display while sliding the coil left and right (and taking average
> readings over a minute or so). With the coil positioned at the ends, signals were
> barely audible, but rose quickly to maximum levels at a location about
> 1-3/4 inches from the end of the rod to the first edge of the coil. Beyond that
> distance, the RSSI values started dropping (but not as quickly as they
> rose within the 1-3/4 inches from the end of the rod.) No matter what MW
> frequency I tuned, there was one small place on the Amidon rod where signals
> were strongest.
>
>
> I taped the coil in this "best" position, disconnected the antenna leads
> from the receiver, and measured the resulting value. It was 533 uH! This
> number is very close to Gary's claimed 554 uH optimum, and obviously beyond
> the 450 uH upper limit stated by SiLabs for an AM broadcast antenna. With the
> coil moved toward the end of the Amidon rod, I measured around 300 uH (all
> but the strongest signals were inaudible with 300 uH inductance on the
> Amidon rod).
>
>
> See below for a short video (1 Mb WMV file) I made of the peaking of my
> local TIS station on 530 kHz using this PL-380 setup. It's a bit blurry, but
> the RSSI and SNR numbers can be seen changing. I placed a triangle of black
> tape on the support frame pointing to the "optimum" position of the left
> edge of the coil to help you observe and hear the signal changes left &
> right of the best spot. It is this position marked with the black arrow that
> results in a 533 uH inductance on my setup.
>
>
> _http://www.mediafire.com/?zdjhxmmmtyz_
> (http://www.mediafire.com/?zdjhxmmmtyz)
>
>
> Here are some photos and captions of different steps of this PL-380
> project: _http://tinyurl.com/ycajpex_ (http://tinyurl.com/ycajpex) Click on the
> thumbnail images and use the PicasaWeb magnifying glass tool for up-close
> views.
>
>
> This modified PL-380 is as sensitive as any slider coil E100 hotrod ULR
> radio I've built and used. I look forward to snagging some TP DX with this
> little wonder! The multiple DSP bandwidths are as useful as those on the
> Kchibo D96L, but the minimal soft mute is an excellent benefit of the PL-380. I
> also appreciate the easy frequency entry and the overall build quality of
> the Tecsun receiver.
>
>
> So what do we conclude about the "correct" inductance for the PL-380
> antenna? First of all, Gary is correct--an inductance of approximately 530-550
> uH when used with the 7.5", 61 type ferrite material from Amidon and 40/44
> Litz wire clearly provides the most sensitivity. Why this is well out of the
> SiLab-recommended range of inductance, I have no idea. Maybe it involves
> the physical size and ferrite mix of the rod, along with the Litz coil
> parameters, although this contradicts what others have said about the Si4734
> chip automatically matching any 180-450 uH coil, period.
>
>
> Whatever yet-to-be-discovered reason for the modded PL-380's behavior, I'm
> happy that fellow DXer and Puyallup, WA resident Gary DeBock has shared
> his discoveries freely with the rest of us. I'm sure he knew he'd get some
> "heat" for his unorthodox claim about modding the PL-380. I commend him for
> not keeping quiet, and for taking a risk to publicize his findings.
>
>
> As a reminder, Gary's article that details this modification to the PL-380
> is found here:
> _http://www.dxer.ca/file-area/doc_details/289-supercharging-the-tecsun-pl-38
> 0_
> (http://www.dxer.ca/file-area/doc_details/289-supercharging-the-tecsun-pl-380)
>
>
> I'm sure others will continue to debate theory vs. hands-on results with
> the PL-380 receiver, but if you'll excuse me I have some DX to snag with
> this little hotrod from Tecsun...
>
>
> 73,
>
>
> Guy Atkins
> Puyallup, WA
> _http://fivebelow.squarespace.com_ (http://fivebelow.squarespace.com/)
>


Re: Guy Atkin's Independent Testing of PL-380 7.5" Loopstick

sdwillingham
 

Gary,

Your results are interesting, but I think it would be good to
take the experiment to the next level. A problem with your
slider method is that it is well-known that loopstick Q is
degraded when the coil is not centered. At the extreme ends,
the effect is severe. I am afraid that your 81-turn coil
may be handicapping the low-inductance values too much.

A good experiment would be to slide your 81-turn coil to the
middle of the ferrite and measure its inductance. Then compute
two winding values that would produce coils with values of
say 330 uH and 550 uH, _when_centered_. Test each centered
coil over a range of stations over the band, strong and weak,
carefully comparing RSSI and SNR. It is also useful to spot-
check the general noise-floor at several points "between"
channels. It is probably necessary to build the coils with
connectors that are easy to swap in order to compare results
without too much error due to time variation of propagation.
(Be sure to retune the radio's frequency after each swap!)

I think a comparison of centered coils with no difference
besides number of turns will be educational and eliminate
possible confounding factors.

-Scott-

--- In ultralightdx@..., D1028Gary@... wrote:

Hi Scott,

Thanks for the clarification. I think if everyone had been clear on this
point originally, it might have saved a few "potshots" directed my way :-)

For those interested, Guy Atkins' modified PL-380 model is now the fifth
such unit to have received a 7.5" Amidon type 61 bar loopstick transplant,
and all of the models have been found (using an 81-turn 40/44 Litz wire
Slider coil) to have maximum AM sensitivity provided when the coil inductance is
somewhere within the 530- 560 uh range.

73, Gary DeBock
(in Puyallup, WA)

In a message dated 2/1/2010 11:23:22 P.M. Pacific Standard Time,
sdwillingham@... writes:






I think there is a bit of a misunderstanding here. The chip's datasheet
indicates a range of inductance over which the chip's built-in varactor
can successfully bring to resonance. This is neccessary, but not
sufficient for calling the antenna "optimal". The choice of which
inductance works "best" overall probably depends on several physical
factors and usage patterns. But once chosen, the chip will
automatically resonate the inductor, which eliminates the factory
alignment procedure which has historically been needed. I don't think
the inductance spec should be read as indicating that all inductances
will perform equivalently; only that all within range can be resonated.

As for the chip tuning inductors outside the specified range, please
recognize that a datasheet is a guarantee of performance. In the case
of integrated circuits, it is critical that a vanishingly small number
of them fall outside the datasheet parameters when deployed in the
field. No manufacturer can afford to scrap complex devices when one of
many chips inside fail to perform as specified. So the numbers in a
datasheet are all conservative, some are very much so.

-Scott-

---------- Forwarded message ----------
From: Guy Atkins <_dx@_ (mailto:dx@_dx@>
Date: Mon, Feb 1, 2010 at 4:56 PM
Subject: Modding the Tecsun PL-380 with an External Ferrite Antenna - My
Experience
To: __ultralightdx@_ultralightd_ul_
(mailto:_ultralightdx@...) _

The SiLab Si4734 chip's datasheet indicates an acceptable 180-450 uH
inductance range for the antenna, and the chip tunes a varactor
capacitor for
best performance on each MW frequency (resonating the LC circuit)... no
manual adjustments at the factory are needed. For the ULR experimenter
this
means there should be NO "best" position (sweet spot) of a coil on the
external
Amidon ferrite rod, as long as the inductance is within 180-450 uH.


Re: Guy Atkin's Independent Testing of PL-380 7.5" Loopstick

sdwillingham
 

I think there is a bit of a misunderstanding here. The chip's datasheet
indicates a range of inductance over which the chip's built-in varactor
can successfully bring to resonance. This is neccessary, but not
sufficient for calling the antenna "optimal". The choice of which
inductance works "best" overall probably depends on several physical
factors and usage patterns. But once chosen, the chip will
automatically resonate the inductor, which eliminates the factory
alignment procedure which has historically been needed. I don't think
the inductance spec should be read as indicating that all inductances
will perform equivalently; only that all within range can be resonated.

As for the chip tuning inductors outside the specified range, please
recognize that a datasheet is a guarantee of performance. In the case
of integrated circuits, it is critical that a vanishingly small number
of them fall outside the datasheet parameters when deployed in the
field. No manufacturer can afford to scrap complex devices when one of
many chips inside fail to perform as specified. So the numbers in a
datasheet are all conservative, some are very much so.

-Scott-

---------- Forwarded message ----------
From: Guy Atkins <_dx@..._ (mailto:dx@...) >
Date: Mon, Feb 1, 2010 at 4:56 PM
Subject: Modding the Tecsun PL-380 with an External Ferrite Antenna - My
Experience
To: _ultralightdx@...
The SiLab Si4734 chip's datasheet indicates an acceptable 180-450 uH
inductance range for the antenna, and the chip tunes a varactor capacitor for
best performance on each MW frequency (resonating the LC circuit)... no
manual adjustments at the factory are needed. For the ULR experimenter this
means there should be NO "best" position (sweet spot) of a coil on the external
Amidon ferrite rod, as long as the inductance is within 180-450 uH.


Re: Rob Ross closing in on # 800

Allen Willie
 

RE:
 
ULR LOG TOTALS are now.......798 Stations Heard
^^^^^^^^^^^^ ^^^^^^^^^ ^^^^^^^^^ ^^^^^^^^^ ^^^^^^^^^

73.......ROB VA3SW

Robert S. Ross
London, Ontario CANADA
 
 
Only a matter of milliseconds now before that magic number Rob , We can feel it in our old  bones. Good Luck in reaching  and accomplishing an awesome feat with # 800
 
Allen W and Dianne F
St. John's NL


Yahoo! Canada Toolbar : Search from anywhere on the web and bookmark your favourite sites. Download it now!


Re: Si4734 Hardware and Software Guides

sdwillingham
 

Roy,

The 9-bit control word is a bit of a pain, but although it is not
obvious, it is not too hard to use a standard 8-bit SPI-type
interface to communicate with the Si4734. The technique is used
in this software:

http://www.silabs.com/Support%20Documents/Software/AN264SW.zip

(See the CONTROL_WRITE and CONTROL_READ macros in file
F320_Si470x_Interface.h. Note, this code is for the Si470x parts,
but works the same for Si473x if you change the chip-address to
0xA0 instead of 0x60.)

The basic idea is to do a 2-byte read or write by packaging the
25-bit command+response or command+data in four 8-bit transactions.
(While manually banging the SENB signal before and after the
32-bits.) The first 25 bits are as documented for the part. The
last 7 bits just hang on as partial extra response or data. When
SENB is driven high, the last partial transaction is aborted and
the control interface state-machine is reset for a new transaction.

Perhaps you can simplify your interface with this technique.

Cheers,
Scott

--- In ultralightdx@..., "Roy" <roy.dyball@...> wrote:
The 3 wire (SDIO SCLK SEN) control interface opened up a big can of
worms because it uses a non standard nine bit control word. I then
discovered I could use the advanced bit banging functions of the FTDI
chip to construct a non standard nine bit word and get my I/O routines
running fast enough to produce good results. By this time it was clear
to me that RS-232 would not do the job.


Re: Three New Ones and a DX Centurian, I Hope

jerrysteck
 

John,

WKY is still loud and clear here in Bryan, Texas at night, altho it seems more subject to fading of late--for a long time i thought that station was south of the border until i caught an enlish ID--hadn't bothered to log it until then--just shows i need to pay attention to detail--

REs
jerry-----k5psh

--- In ultralightdx@..., "John H. Bryant" <bjohnorcas@...> wrote:

I was particularly happy this morning to also log KRKY, north of
Denver on 930. Until fairly recently, WKY-930 in nearby Oklahoma City
has dominated 930 nights as well as days. Several years ago, 1920s
WKY shifted to all SS and their signal has slowly deteriorated.