XHDATA D-808 Longwave fix?

Medium & long wave receiver discussion
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AMDXHUN
Posts: 261
Joined: 03 Nov 2018 21:25
Location: Szekesfehervar, Hungary

XHDATA D-808 Longwave fix?

Post by AMDXHUN »

Almost deaf on LW, but very good on MW. Any suggestions to fix it?

KPC850
Posts: 145
Joined: 20 Aug 2016 15:49

Re: XHDATA D-808 Longwave fix?

Post by KPC850 »

You could simply put a greater number of windings on its ferrite rod, so it will work properly on LW.

However you will loose a big portion of MW which will become deaf.

It is impossible for the one winding that it has on the ferrite rod to properly cover LW as well as MW (which is why it goes deaf below approx 350 kHz).

Ideally replace current ferrite rod arrangement with one with seperate LW and MW windings and a switch to switch between them when you change bands.


(These DSP radios automatically match to the ferrite rod winding inductance if it is in within range, so there is no alignment needed,)

Jean-Luc
Posts: 20
Joined: 17 Feb 2016 17:02
Location: Central France (JN06UT)

Re: XHDATA D-808 Longwave fix?

Post by Jean-Luc »

Hi there,

An easy fix for the XHDATA deafness on longwave ;-)

https://youtu.be/WmZrhOjVfeA

73 Jean-Luc
Perseus + Wellbrook loop
RTL dongle + 3 el yagi in loft

chipbutty
Posts: 74
Joined: 02 May 2019 09:42
Location: Sheffield

Re: XHDATA D-808 Longwave fix?

Post by chipbutty »

LW is so bad on the 808 I disabled it. MW is a different story of course.
Sangean ATS-909X, Tecsun S-8800, Sangean PR-D5, Eton Elite Executive, Roberts R861, Tecsun PL-310ET, Grundig Yacht Boy 400, Radiwow R-108, Tecsun R9700DX, Grundig City Boy 700, Philips D1835, Realistic DX-360, Panasonic RF-3500, Sony XDR-P1DBP.

KPC850
Posts: 145
Joined: 20 Aug 2016 15:49

Re: XHDATA D-808 Longwave fix?

Post by KPC850 »

not about LW but SW :

I notice the low end of shortwave / HF on the XHDATA D808 can have images of strong shortwave signals on much higher frequencies. These images are more likely to be noticed (depending on frequency) on the wider AM bandwidth settings as they may not fall exactly on frequency.

These images are very 'narrow' and moving up or down just by 1kHz can cause them to disappear - a tell-tale sign of images of much higher frequencies and useful to know to eliminate any image effects on actual AM transmissions in the low end of HF.

so for example 1734kHz had an image of 11780
other images I have noted: (image and the originating frequencies with strong signals)
1716<-11650
1734<-11780
1735<-11785
1757<-11940
1766< 12005
1770<-12030
1781<-12110

2256<-15430
2304<-15770
2312<-15825
2732<-18765

(the strength of images appears to diminish with increasing frequency)

The relationship seems to be: to get the originating frequency multiply your image frequency by 7 and then subtract 360 kHz.You will now have the originating freq, or at least within a couple of kHz if not exact.

The same images are likely to be noticed on other radios using the same DSP chip. A filter could of course be effectively used if using an external aerial, if images are a problem.

It is useful to know the above in case these usually weak images are mistaken by DXers as an actual transmission on the frequency! I am not criticizing the receiver, no other receiver I have used is free of some image effects or other. The listener can improve matters with an external aerial and filter to deal with any images

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