Re: Early results of 7.5" Amidion rod

Gary DeBock

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 .
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. 
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

From: Roy com>
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.



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