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Author Topic: looking for dds vfo with bcd outputs to switch a band pass filter for Juma RX1.  (Read 5369 times)
KH2BR
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Posts: 98




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« on: February 17, 2013, 03:14:39 PM »

I have been looking all over the internet for a dds vfo that has bcd outputs that I can use to switch in band pass filters for each band
that the vfo is tuned to. I dont know how to make my own pic code to make one do what I want it to do.

I am modifying a Juma RX1 receiver. The receiver only covers 40 meters and down but I want more coverage.
I removed the original dds vfo and replaced it with one from N3ZI  and it is a exact match physicaly to mount above the receiver board.

It works like a champ and covers all bands but It only has one bit that I can switch so It will only switch two band pass filters. I put a rather big band pass filter in for 20 meters from KitsAndParts and was realy surprised of how well it worked. I was also able to pick up some 15 meter signals but rather weak for an obvious reason.

 I have a band pass filter kit on the way from Kess K5BCQ  www.qsl.net/k5bcq/Kits/Kits.html 
that I will use in the small radio, so instead of using a seperate bcd switch, I sure would like to have a VFO that has band switching output that I can use. So, any one out there have a good source to what I am looking for?

I know I can make my own, but would rather use what is out there, life is short and dont want to spend that time playing around designing something.

Robert KH2BR

Robert KH2BR
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W4OP
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« Reply #1 on: February 17, 2013, 04:29:10 PM »

Have you looked at Jim Hagerty'y DDS? I see he now has bandswitch input and you could likely use his DDS and this board  to control your filters:
http://www.wa1ffl.com/rotaryVFOcontrol.html

Let us know how you progress.
Dale W4OP
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KH2BR
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Posts: 98




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« Reply #2 on: February 17, 2013, 05:22:50 PM »

Hi Dale,


Thanks for the fast response and info. I checked it out and the price is way to steep and with the add on board for band switching, you still have a knob to twist and the only knob I want to turn would be the vfo knob.

PA0KLT at sdr-kits has a SI570 vfo that has outputs for band switching and it goes down to 3.5mhz but, output is a square wave and additional LP filtering would be needed due to harmonics.There also other buttons to add.  I would like to use the vfo with a transmitter and not have to worry about harmonics. I could give it a try. I saw that price and said WOW !!  cost more then the Juma RX1 and the N3ZI dds cost me $45 bucks. so I need to keep the cost down. It should not be to hard to add bcd band switching outputs to a pic and not cost that much. I may be forced to make my own.

73's, Robert KH2BR
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K8AC
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Posts: 1464




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« Reply #3 on: February 25, 2013, 02:13:48 PM »

Way out of the price range you stated, but check out the IQPro DDS VFO.  I'm aware of the other DDS VFO kits and use one of them as well, but the IQPro design covers all the bases and can control external relays for band switching.  Plus, the source code is available free from the author.  That might give you some ideas on doing your own thing.

73, K8AC
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TANAKASAN
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« Reply #4 on: March 02, 2013, 09:12:22 AM »

This isn't exactly what you're looking for because the outputs to switch the bandpass filters are not in binary, but it might give you some clues.

http://www.analog.com/static/imported-files/application_notes/AN-557.pdf

Tanakasan
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2E0SDR
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« Reply #5 on: June 05, 2013, 01:43:50 PM »

Try DX Kits at www.dxkits.com, they do exactly what you are looking for.
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AK2B
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Posts: 94




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« Reply #6 on: June 06, 2013, 02:02:37 PM »

I use the K5BCQ controller kit II on the same page of your url. I use it to controll the same multi-band BPF board that you mentioned and it works quite well.
Tom, ak2b
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KH2BR
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« Reply #7 on: June 11, 2013, 11:18:01 AM »

The K5BCQ controller LCD is to long, not backlight, and is single line. It will not fit inside of the Juma RX-1. I don't think that the LCD can be changed from serial to parallel input display.
The DXKits VFO is out because it is not surface mount and will not look like the all surface mounted parts in the Juma RX-1
What are all of those switching transistors doing there? Whats wrong with using a multiplexer / demultiplexer bus switch? that would be much simpler.
I will study the AVR band switching in the DXkits. The AVR is the same as in the PA0KLT dds vfo but band switching is not the same since its a custom AVR.
Replacing the PA0KLT AVR with the one from DXkits could work, but I have to study the band switching. I may have to slightly modify the switches on the BPF board to make it work the way I want. I don't understand why on the WB6DHW bpf board bits 011 and 100 were skipped over and not used. Strange.
The manual rotary band switch is not a option.
Robert KH2BR
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AK2B
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« Reply #8 on: June 12, 2013, 09:19:12 AM »

I was referring to the Controller II which doesn't use the serial LCD but a standard backlit LCD instead. It is only available as a partial kit but the rest of the parts are a cheap order to mouser. The WB6DHW BPF board doesn't really skip over two i/o's, they are for two additional BPF's of your choice. The Controller II kit firmware and hardware accommodates switching the board based on user settings on a band by band basis. I built the smd coil version of the BPF. The toroid version my be a bit better.
The Controller II is the last item on this page: <http://www.qsl.net/k5bcq/Kits/Kits.html>
Tom, ak2b
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KH2BR
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Posts: 98




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« Reply #9 on: June 12, 2013, 11:18:24 AM »

Thanks Tom,
I think you saved me from cutting up my BPF board. I will get ahold of Kess and get his controller II then give it a try. I like the idea of being able to set my own switching points for the BPF. This is what all of the others do not provide.
 What I meant by the bits being skipped over is that the logical sequence of those bits had been skipped over. They should have been placed at the end or start of the counting sequence.
73's Robert KH2BR
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AK2B
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Posts: 94




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« Reply #10 on: June 13, 2013, 10:06:48 AM »

Hi Robert,
The controller II is actually pretty slick. Each time you program a memory location, you include the frequency, IF offset and which BPF you want to use. The BPF is selected with the binary number of the BPF switch. I guess that's why I didn't consider the switching number sequence of any importance.
The controller II is also capable of control via a PS2 keyboard. I used a keypad instead and translated PS2 keyboard keystrokes using a Teensy board. This info is available in the files section of < http://groups.yahoo.com/group/AQRP/ > - The Austin QRP Club's website. There are also sa scans of the WB6DHW BPF board in the same place.
Tom, ak2b
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KH2BR
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Posts: 98




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« Reply #11 on: July 25, 2013, 11:29:15 PM »

I went ahead and got the SI570 Controller 2 from K5BCQ along with the band pass filter kit and installed both of them into my 2 band Juma RX1 and I am so pleased with it. Now I have all bands except for 160 meters because the controller only goes down to 3500 mhz. I did not want to install a divider that would give me that particular band with the SI570 running at a higher frequency. When I set up the controller in the band pass filter settings screen, there is a area under the frequency that something can be entered. I have looked every where and even posted to AQRP yahoo users group and still no luck.
If anyone knows what is entered in this area, I would appreciate the information very much.
All I have remaining to install is the hypermite cw filter from 4sqrp and will be grinning from ear to ear.
I also installed a low pass filter on the Controller in a empty space. A small double sided pc board was used and works quite well. I tried a perf board and the wave form looked like the sinewave was weaving in and out of the holes in the board.

Robert KH2BR
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AK2B
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Posts: 94




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« Reply #12 on: July 31, 2013, 10:21:44 AM »

Hi Robert,

< http://www.qsl.net/k5bcq/Kits/SDR2GO%20Builders%20Notes_V2.0.pdf >
Look in the above PDF under the 'TEXT' heading and you will find that the bottom line can only be set externally via a 5 pin header called J7. I just put my call in one of the preset messages. I can't remember which one.
I think this is what you are looking for. If not, let me know.

Tom, ak2b
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