Topics

RX BCI filters

 

We will have BCI kits out in the next week or so for the bitx radios as well as other direct conversion receivers that suffer from close AM stations.

The drop off is right at about 3Mhz and will cost 5$+ shipping. 3x toroids and 4x caps will be used, this would be a good kit to learn about wrapping toroids for those that have not had a chance to try.

They are RX ONLY! and should not be placed in the TX path, we will have detailed specs and instructions for both the Bitx40 and uBitx radios.

73
--
David

 N8DAH
Kit-Projects.com

Shop is open!

Curt
 

Interesting for those close to big medium wave transmitters. But it seems to me there is a larger market to kit something to remedy v3 and v4 ubitx transmit spurious. What am I missing in our greater interest in only improving what we hear?

Curt

 

Curt,

 As much I would like to make a spurs/harmonics kit I can only make products for which I have equipment to test. If I was to make a kit for the spurs and harmonics I would be doing so on blind faith of others work. Maybe once I can afford the equipment I can make a kit for it but until then I do what I can.
--
David

 N8DAH
Kit-Projects.com

Shop is open!

 

Check this kit out...it’s what I am currently building for my version 4...go to https://www.ebay.com/itm/KIT-Universal-Bandpass-Filters-for-HF-Transceivers-BPF-6-6-bands-12V/172672735615?hash=item283418d97f:g:VtYAAOSwXj5aon5k

David Posthuma, WD8PUO

 


From: bitx20@groups.io on behalf of N8DAH <dherron@...>
Sent: Saturday, July 13, 2019 10:19 PM
To: bitx20@groups.io
Subject: Re: [BITX20] RX BCI filters
 

Curt,

 As much I would like to make a spurs/harmonics kit I can only make products for which I have equipment to test. If I was to make a kit for the spurs and harmonics I would be doing so on blind faith of others work. Maybe once I can afford the equipment I can make a kit for it but until then I do what I can.

RICHARD
 

Yeah!! More power who cares about the rest of the spectrum

K6KWQ

 

Sent from Mail for Windows 10

 


From: BITX20@groups.io <BITX20@groups.io> on behalf of Curt via Groups.Io <wb8yyy@...>
Sent: Saturday, July 13, 2019 7:08:44 PM
To: BITX20@groups.io
Subject: Re: [BITX20] RX BCI filters
 
Interesting for those close to big medium wave transmitters. But it seems to me there is a larger market to kit something to remedy v3 and v4 ubitx transmit spurious. What am I missing in our greater interest in only improving what we hear?

Curt

Curt
 

David

Few of us can afford or choose to buy a spectrum analyzer. Some are having success with a SDR in measuring spurs, and I want to explore this route.

We can trust the results of the community. The circuit board designed by Gordon Gibby has been found to he highly effective in fixing harmonics, curing the major source of cw spurious. Kitting this could bring business to someone's store. Part 2 to cure mixing spurious has proven more difficult. A second xtal filter at 45 MHz was troublesome in my rig, but perhaps when I try shielded inductors might work better. 

Yes others having fun with putting on the blinders. My rig is dreadful on 12m, maybe not as bad on the other bands.

Curt

Mark Hatch
 

In regards to a spectrum analyzer....

The SDRPLAY has some add-on software that provides a basic spectrum analyzer. I used it to peak at my spurs/harmonics before and after. Could see the difference the changes made (relays and inductor). Again, wouldn't use this for absolute, but I could measure the db of spurs and harmonics and see that I was compliant except on the 10m band.  And with a noise source, you can look at the impact of filters too. Again, this will not replace a $2k+ spectrum analyzer, but I already had a SDRPLAY that I used with my IC-7300 as a spectrum display....

73
Mark

Christopher Miller
 

One of the maker spaces here in Tucson holds a low power fm radio license. They have all sorts of rf test equipment. I live in Tucson, so it’s probably worth while to just check and see if that is available near you.

KF4FTR

 

On Sat, Jul 13, 2019 at 10:37 PM, David Posthuma wrote:
https://www.ebay.com/itm/KIT-Universal-Bandpass-Filters-for-HF-Transceivers-BPF-6-6-bands-12V/172672735615?hash=item283418d97f:g:VtYAAOSwXj5aon5k
Hi David,

Could be quite useful for BCI and other out of band receive interference, but I don't think it was made for transmiter harmonics/spur reduction.

73,


Mark.

 

Filters have been release!

https://shop.kit-projects.com/index.php?route=product/product&path=59&product_id=118

I will have plots and data up soon, working on getting better screen shots.
--
David

 N8DAH
Kit-Projects.com

Shop is open!

 

If anyone has been trying to order a kit and could not get the order through it was a slight mistake on my part please refresh and try it again now with the kit option!

sorry for the mix up and thank you Steve AA7U for bringing it to my attention.
--
David

 N8DAH
Kit-Projects.com

Shop is open!