Re: Early results of 7.5" Amidion rod


Roy <roy.dyball@...>
 

Thank you Gary and Neil.

Having the Si4734 tell you what's going on regarding the capacitance/inductance of the loopstick is a real bonus and makes fine tuning easy. Gary I think the 81 turn coil is too big. The 81 turn coil really worked well on LW, it was almost 45 dbu and 25 S/n db above the stock PL-310 on my local NDB (311Khz). At 81 turns the G8 reported the inductance as 630 uh at 520Khz.

Neil I would not hesitate to use your ferrite rod to practice with until your Amidon rod arrives. I would use the wire wrap wire and work on a coil length of 30mm or 60mm for spaced winding (just wind two wires together then unwind one).

I also have never heard a station from Western Australia. Receiving 1323 Cruise AM last night is my best so far (1600KM) without an external aerial. I woke up about 3AM and just had to try the 7.5 inch Amidon, admittedly  I had turned off the soft mute on the G8 and had selected 2Khz bandwidth. I find 1Khz although showing better S/N can be a bit muffled when you are trying to get an ID.

Winding coils is fast and easy with these little Tecsun's so wind a couple of different configurations and compare them. I hope it works out well.

Cheers Roy

--- In ultralightdx@..., D1028Gary@... wrote:
>
> Hello Roy and Neil,
>
> Thanks for your comments on our group, Neil.
>
> Roy, in my previous post there was a description of the method that Steve
> Ratzlaff and I used to optimize AM reception in the Tecsun PL-300WT and G8
> models, and to determine the optimum loopstick coil inductance for peak AM
> sensitivity in the stock models (and in the 7.5" Amidon loopstick transplant
> models). That procedure is actually described in a file posted in our
> Ultralightdx site (under modifications), and is also directly linked at
> _http://www.mediafire.com/?jyjg5hmkyqm_ (http://www.mediafire.com/?jyjg5hmkyqm) .
>
> Once we determined the optimum loopstick coil inductance for peak AM
> sensitivity in the models, we simply wound a fixed 40/44 Litz wire coil of the
> same inductance on the 7.5" Amidon ferrite bar, and obtained great results
> every time. Although their AM sensitivity was equal to the best of the
> modified Ultralights, unfortunately the fixed 3 kHz DSP selectivity in the 7.5"
> loopstick PL-300WT/ G8 models made them uncompetitive in transoceanic DXing
> when compared to the CFJ455K5 filter-modified E100 Slider and SWP Slider
> 7.5" loopstick models, so we didn't make too many of the modified PL-300WT/
> G8 models last spring.
>
> 73 and Good DX, Gary
>
>
>
>
>
>
> In a message dated 1/13/2010 5:51:24 P.M. Pacific Standard Time,
> neil.findlay52@... writes:
>
>
>
>
>
> Hi all
> And a question to Roy
>
> Currently using a 310 and a 380 with my Palstar R30a with 3 Kaz antennae
> as my spotter reciever
>
> Just got my order of 40/44 litz wire, not yet got the Amidon rods. I do
> have a flat rod of unknown
> ferrite type ( probably bought from local electronics supplier years ago )
> it is 7&7/8 inch long by
> 3/4inch by 3/16 inch - The comment seem to indicate that flat is not ideal
> but at that size would it
> be worth a try. I am off work / working from home at around 40% for two
> weeks after a minor
> operation so will have some time and the Amidon rods wont arrive in that
> time.
>
> Roy
> I am interested in what ypu have been able to hear from the East and North
> East also have you
> ever heard a Western Australian station. I live at Rothwell ( on the edge
> of Deception Bay) just
> going off the Redcliffe Peninsular. I have heard Fiji and many New
> Zealanders. I can hear a lot
> of asians but not good at recognising the languages. My son knows some
> japanese and can rcognise
> so will try for some of the powerhouses that Gary hears ie 747 etc. I have
> never heard a West Aust
> yet. My other project is to get the Vactrol connected to the 3 Kaz antenna
> and wind a coupling on to
> the 380 - I have some wire wrap from years ago computer projects.
>
> This is the best group that I have part of in Medium Wave - a most
> co-operative group covering
> listening and technical even part of the design team of our prime chip.
> Thank you for everyones effort
> and for making the information available
>
> Neil
>
>
>
> ____________________________________
> From: Roy roy.dyball@...
> To: ultralightdx@ ultrali
> Sent: Thu, 14 January, 2010 10:50:38 AM
> Subject: [ultralightdx] Early results of 7.5" Amidion rod
>
>
> Hi All
> The first coil was wound on the 7.5 inch rod with 165/46 spaced using
> 0.7mm solder as the spacer which is about the same size as the Litz, wound over
> 110mm centred on the rod. The capacitance reported by the G8 showed it had
> bottomed out at 1710Khz. I removed 2mm from each end and the capacitance
> showed 18 Pf at 1710Khz (7pf is the lowest). This resulted in aprox 15dbu
> increase on the G8 when compared to a stock PL-310 set a 3Khz bandwidth,
> holding this to the end of the band.
> I was able to hear a station in another state on 1323Mhz (Cruise AM in
> Adelaide) last night that I have tried on and off and have never been able to
> receive at a distance of over 1600 KM (great circle) while listening with
> the radio on my bed side table.
> I then decided to emulate Gary's 81 turn 40/44 coil starting at 43mm. The
> G8 reported it was bottoming out of capacitance at 1540Khz. I ran my
> standard tests and found this configuration was performing the same as the 165/46
> coil at the bottom of the band but was dropping off by around 1200Khz (2-3
> dbu).
> I had to unwind 18 turns to get the G8 to report a value of 12pf at
> 1710Khz. This only dropped the very end of the (low) band by 2 dbu but had
> started to pick up by 1200Khz. I won't know how well it performs until tonight
> when the high end of the band opens. For now it is performing aprox 13dbu
> better than the stock PL-310.
> Gary has reported that his coil shows a better improvement when fitted to
> the 380 than the 310. Probably this coil would perform better in the PL-380
> than the G8. I will try that later. I am also going to rewind the first
> coil but use 0.5mm spacing.
>
> Roy.
>
>
>
>
>
>
> ____________________________________
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>

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