Shortwave Capture

[gbaars]

Switching off IC5 can
simply be done properly
with a BS170 or BC547C in
the groundline of IC5
(between pin 3 and ground).

[mikemike]

HI. I have used ribbon cable for all my wiring with no problems after removing R4. Still have to case it all up, but will be using a separate keypad on a metre of cable. It's more convenient and will stop me pushing the receiver off the back of the workbench! See from photo's that you have same problem of finding correct 'S' meter.
Another way of avoiding voltage drop to IC5 is to use a small relay with the extra transistor, I think I will disable SSB altogether since all I required was a decent portable DRM receiver, AM is good and will set up FM once screening is complete. FM is possibly only for CB at the moment and that is plagued by 'pond life' round here.
Will check to see if I have same problem with the SSB oscillator continiously running.
Glad you like the Dream software, Steve, its good, have been using it for several years. One day all serious receivers will have a spectrum display, if you ever get a chance take a look at the WINRADIO set up, The display of these SDR radios is great. To be able to see the signal and all just beside it is invaluable.
Mike

[sarma]

Hi, I am attaching a transistorised version below as a .gif file.
Mr Steveg may try it out instead of BS170 modd



Sarma

[sarma]

Hi Steveg,

I accidentally removed it and shall put back with slight mod as the author was opioning drop of 1.5V,

i shall be putting a new schematic in another hour or so.

the Photos are really NICE. I thought the cable is shielded by a metal foil and connected to earth-- but to my surprise you took more pains in 5 individual shielded wires. -- i think, after removal of 4.7 ohm resistor, there may not be need for screened cable-- please check.

the BS170 application you may perhaps try out on a seperate board as a circuit element

Regards

Sarma

[steveg]

Hello Sarma
How did you add your circuit diagram to the forum. I do not seem to be able to copy and paste. I had to use the attach option for my photos, which are then too large for the good resolution of the jpeg image.

[steveg]

Hello GBaars.
I am sure the ssb detector interferes. I was able to see the signal on the dream display with all controls at minimum and no aerial connected. I have removed the supply to the detector and the signal has gone and there is no interference. Do you have another suggestion please to switch the ssb detector on and off with the controller?

[steveg]

Hi Sarma and anyone else
Still playing with the radio. I have now added the rf preselector from the july/august 2006 article, using my own tuning voltage. This has made a huge reduction in the spurious signals received, cleaning up the received signal really well. I no longer use the audio section of the radio but prefer to feed the signal through the dream software for all demodulation. Still happy with the radio, and I prefer it to the latest sdr radio from elector (should hope so considering the cost difference). I do use a loop aerial as I have no access to outdoor space.

[sarma]

Hi Steveg,
Nice being able to contact after the site updation. A pre selector is always a healthy item, to my beleif. it amouts preconditionig.

as he item is alredy afforded by you , you can improve on it and see that its performance is almost near Yeasu Rx.

I have my PCBs locally made on have , now after a long delay. I am still starved of 44.545MHz and 45M15B1 filter. i am not able to source them in India till date. otherday someone 'rfplus' put them as sets for sale on ebay australis- but stocks exhauted by the time i couled register and reach --
it was really a cheap bargain.

i intend, developing software locally, with help of another friend.

mean time, we from India, get few reports of DRM reception here and there. say Kuwait on 13620KHz received at West coast state "GOA"

for normal reception no use of depending on PC as lot of power wastage and interference also.

sdradio, i am trying another version, using AD9851 DDS-VFO followed by 74HC74,74HC4052 & LM358.

i did purchase a kit for dds-VFO with 9851, and PIC16F877 from Shaji P B (VU3WIJ) --details can be had from
http://www.hamradioindia.org/forums/viewtopic.php?t=857

Regards
Sarma

[sarma]

Hi Mark,

Hope you must have finished the testing by now and the rx must be working fine--

Hope to see your remarks as a latest assembler of the kit

Sarma

[sarma]

Hi Steveg,

Four months have passed after your mod for Preselection and AGC, hope to hear your comment soon the reception satbility and also details of loop antenna.

I would like to implement one, as I stay in the second floor of an apartment dewlling.

Also please indicate whether DX reception of DRM stations could be possible. We get DW english languge program relay from Trincomae-Srilanka. this station is aroud 1200Km for Hyderabad (India) and my SW capture is gtg ready still for want of 45M15B1.

meantime I am using an SDradio designed around a local oscilltorbuiltin, and 74HC74,74HC4053&Ne5532- to get I/Q output. then as suggested we listen to normal stations using SDRadio1.0

DRM using Dream shows at -85db--too low for recogntion by software. Co-axial loop antenna is set up on an outer door but needed amplification.
Sarma