KitsAndParts.Com Forum

ak2b · 2008-11-29 12:46:09

Hi Gary,
In Manhattan the utility poles are underground which helps a lot. My antenna is a Force 12 GT-5 vertical dipole on top of the apartment building where I live. It is up about 110 feet from the street which is good but I had to run 200 feet of coax to get to my rig. 20 meters, which is my favorite band, is usually pretty quiet although I get my share of "what the hell was that?" noises that come and go at random. 40 meters is very noisy around here but then 40 meters can be pretty noisy anwhere.
I was operating mobile up until 6 months ago when I got another car and haven't reinstalled the rig yet. Other than the usual noises from traffic lights, city buses, etc. by the time I got on the Belt Parkway, on my way to work, I could work the world with very little effort with an IC-706, AH-4 and a Radio Shack CB whip. Driving near the ocean never hurts .

Tom, ak2b

ak2b · 2008-12-01 17:57:48

I just finished this 40 meter receiver with universal VFO
It works pretty well but I ran out of mounting hardware so it's just pinned to a cardboard box . Hardware should be in this week.

Tom, ak2b

W8DIZ · 2008-12-01 18:14:22

Hi Tom,

I built the same style rig but had the RF amp in front of an SA612 Mixer
All the rest was the same.

ak2b · 2008-12-01 19:14:27

W8DIZ wrote:
I built the same style rig but had the RF amp in front of an SA612 Mixer
All the rest was the same.

Hi Diz,
Did you put an rf amp after the sa612 mixer or did you go straight into the crystal filter?

W8DIZ · 2008-12-01 19:52:04

ak2b wrote:
Did you put an rf amp after the sa612 mixer or did you go straight into the crystal filter?

Yup...no amp after the mixer.
The SA612 has gain...so no need to place an amp after the SA612 mixer to the Xtal filter.

-Diz

W4GNS · 2008-12-01 21:29:04

The toroid on your VFO looks fine, at some point in my life I gotta wind mine...... too bad DIZ did not offer to wind that for 2 bucks, like he did for soldering the SMT diode on the diode ring mixer board

UPDATE: After posting the above comment, I checked my VFO bag, its still in the same condition that DIZ shipped it So I figured it was time for me to do it , since it does not seem willing to wind itself. To be honest I enjoyed winding it so much , I wound it a second time !! don't ask !

foot note: its a VERY good idea to take extreme caution when cutting the tape after being applied to the toroid to NOT cut the pig tail flush with the 'roid (yea, I cussed)

ak2b wrote:
I just finished this 40 meter receiver with universal VFO
It works pretty well but I ran out of mounting hardware so it's just pinned to a cardboard box . Hardware should be in this week.

Tom, ak2b

Last edited by W4GNS (2008-12-01 23:20:09)

ak2b · 2008-12-02 09:05:23

Overall, I've found that gain is definitely not an issue with the two receivers I’ve built. In fact, just the opposite, there is way too much gain. Which is why I used the 10K pot to apply voltage to pin 2 of J4 on the IF amp and lower the gain in the audio amp by adjusting R3. I also found an immediate need for audio filtering – which makes a big difference.
Just for fun, I swapped the RF amp from the output of the diode ring mixer to the input but really couldn’t hear much difference. Then again, it was late and the band was dead. It’s nice that it’s so easy to do .

Tom, ak2b

kc0wox · 2008-12-02 09:47:43

The reason to have the rf amplifier first is to establish a low noise figure. That might be a big deal at 6 meters but on the lower frequencies, the external noise will be higher than the internal noise figure anyway.

The rig looks great!
Leonard

ak2b · 2008-12-06 16:14:09

I found a variable crystal filter described by YU1LM here:
http://yu1lm.qrpradio.com/XTAL-VAR%20FILTER-YU1LM.pdf
It looked interesting because it was simple and has a 50 ohm input and output termination.
Using one of Diz's Universal Generic PCB's I built up the circuit (the smd resistors are on the bottom):

It worked ok. I didn't really have the right varactor diodes to get a narrow enough CW bandwidth so I put them in parallel which was better but still not quite what I want to see.
Here are some Spectrograms that give you an idea of performance:

And lastly a Spectrogram the audio detector adjusted for SSB.

Which sounds like this (you can hear the pot being varied between wide and narrow in the beginning and near the end if you listen closely). The recording is K6AER.
http://tomnyc.no-ip.org/k6aerssb.mp3

I think I need to get some other varactor diodes. The ones Elecraft uses look pretty good with a nice wide C min/Cmax ratio. They are 1SV149's. I couldn't find them anywhere. As a matter of fact, Mouser doesn't seem to stock any varactor's.

Tom, ak2b

P.S. Those Generic PCB's are really very nice. They take SMD's very nicely

W4GNS · 2008-12-06 16:55:22

Tom
A quick google search popped up 1 result here http://www.bdent.com/search/part.jsp?partnum=1SV149B they appear to be available in small quanities

I just noticed there is a $15.00 min order

Last edited by W4GNS (2008-12-06 21:07:39)

ak2b · 2008-12-08 13:07:31

Gary, Elecraft wrote me back and said they (1SV149) would be $0.80/ea. Not bad. That's a lot better than $3.88/ea.

Tom, ak2b

W4GNS · 2008-12-08 13:14:47

At that price difference, I think you better get extras! Thanks for the update, Tom

After even more research, I see you're getting a steal Tom,found these http://www.mouser.com/Search/Refine.asp … rd=MVAM109
should serve the same purpose but different, not sure why I'm researching, cuz I have no intentions of doing the variable BW filter

ak2b wrote:
Gary, Elecraft wrote me back and said they (1SV149) would be $0.80/ea. Not bad. That's a lot better than $3.88/ea.

Tom, ak2b

Last edited by W4GNS (2008-12-08 19:20:39)

ak2b · 2008-12-13 17:48:51

I made a grainy (not on purpose) video clip of my 40 meter receiver with VFO. I did it with my regular digital camera. The sound is picked up from cheap computer speakers and doesn't sound nearly as good as through ear-buds. In the movie I mention that I can't remember where the display came from. It is from KD1JV and sold by QRPkits.com. I would caution anyone thinking of building it since it uses little tiny 802 size smd's. Without some experience, you might find this kind of difficult. I put solder paste on all the pads, mounted the parts, put it on a heating tray used a heating gun when the paste turned dull gray. I only had one short between IC pins and two pads where I forgot to put solder. It came out pretty well. It is coupled to the VFO output through a 4.7pf cap.

tomnyc.no-ip.org/ErectorRXmovie.wmv

...And a short recording that I made earlier from the same receiver, when the band was a little better, that sounds more like the radio.

tomnyc.no-ip.org/All_Homebrew_Here.mp3

Tom, ak2b

W4GNS · 2008-12-14 01:52:41

Tom
What bandwidth's did you end up with, with your own crystal filter? Or is that the Nescafe that is helping to? I like tight filters and yours appears to be tight.
Slowly but surely I'm making some progress, I will use the multipig + PLL with my rig (I hope). These 14 hour work days are really making my hobbies tough to make time for ;-(
Fine show Tom........

ak2b wrote:
I made a grainy (not on purpose) video clip of my 40 meter receiver with VFO. I did it with my regular digital camera. The sound is picked up from cheap computer speakers and doesn't sound nearly as good as through ear-buds. In the movie I mention that I can't remember where the display came from. It is from KD1JV and sold by QRPkits.com. I would caution anyone thinking of building it since it uses little tiny 802 size smd's. Without some experience, you might find this kind of difficult. I put solder paste on all the pads, mounted the parts, put it on a heating tray used a heating gun when the paste turned dull gray. I only had one short between IC pins and two pads where I forgot to put solder. It came out pretty well. It is coupled to the VFO output through a 4.7pf cap.

tomnyc.no-ip.org/ErectorRXmovie.wmv

...And a short recording that I made earlier from the same receiver, when the band was a little better, that sounds more like the radio.

tomnyc.no-ip.org/All_Homebrew_Here.mp3

Tom, ak2b

kc0wox · 2008-12-14 09:17:27

I have 2 videos on the digital dial. One on assembly and one on troubleshooting it. You can see them at:
http://golddredgervideo.com/kc0wox/digi … sembly.wmv

and

http://golddredgervideo.com/kc0wox/digi … ooting.wmv

They are large files, 124 meg and 212 meg so may take some time to download.
Leonard
kc0wox.com

ak2b · 2008-12-14 15:45:15

w4gns wrote:
What bandwidth's did you end up with, with your own crystal filter? Or is that the Nescafe that is helping to?

Gary, the crystal filter you were listening to is the variable bandwidth filter - the curve is shown in a previous post above. The Nescaf helps a lot and I wouldn't use the receiver without it at this point. You need some sort of audio filter in my opinion. There is probably more than one solution to this like using something before or after the audio amplifier instead of using an outboard filter like I do. I like the Nescaf which is probably why I haven't spent too much time on another approach.
Also, having the IF pot can make things sound pretty quiet. I can see why some hams prefer to ride the IF gain(or in most cases, the RF gain) instead of using their AGC. The only thing you have to keep an eye on (or ear on) is coming across a sudden strong ear-splitting signal

Tom, ak2b

ak2b · 2008-12-15 09:50:49

I've added a Universal Dual BandBass Filter (20 and 17 meters) and another FCC-1/2 to get multiband by moving a few jumpers.
The pots are all 10K and going from left to right are the variable crystal filter pot, IF gain pot and the volume control.
The two left pots have 4.7K resistors on the ground side and the input side is connected to the 8V line with the center as the control lead. The filter pot is not connected as it previously shorted to the circuit board when it wasn't mounted and now the variable crystal filter doesn't want to work anymore . I replaced the pot since it acted like a fuse. The crystal filter in there now is a narrow, about 350 Hz filter.
I mounted a small piece of PC board material on a nylon standoff and soldered the main +12V lead to it. I also mounted a strip of 5 pins (the same as the 3 pin female connectors at the end of each small board) on the same board so that I would have several sources of +12 volts. I did the same a strip of ground pins soldered directly to the main PC board backplane. You can never have have enough voltage sources.
I found a reference Diz gave in the FAQ notes on the MultigPlus and ordered a bulk supply of connectors from Jameco. http://kitsandparts.com/faq.php

Video:
tomnyc.no-ip.org/ErectorRXdds.wmv

So now I have a decent platform for adding/removing/changing boards and general experimenting.
Now if I only knew what I was doing .

Tom, ak2b

W4GNS · 2008-12-15 11:50:18

We are suppose to know what were doing?!?!?!?!?! First I have heard of that
News Flash: I have upgraded my mobile lab ! (Youre gonna love this one Diz) see second picture http://www.w4gns.com/trk.html

ak2b wrote:
Now if I only knew what I was doing .

Tom, ak2b

Last edited by W4GNS (2008-12-15 14:55:25)

kc0wox · 2008-12-15 14:45:37

Nice video. The setup looks good.

I don't know about that funny souning, intermittant, tone that was on the speaker though. I was waiting to hear someone speak.
Leonard
( a newly licensed no-coder )

jaswarb · 2008-12-24 08:58:24

Hello Tom,

I am Jim Benson NS5U. I am collecting parts to build a 30/20 meter version of a "Dizzy Transceiver" and have a few questions. I have been following your developing rig with great interest. I have aquired a FCC-1/2 for the VFO and now I am looking for guidance to choose the RF-ToolKits to accompany it.

Specifically:

Choice of IF frequency would seem to be narrowed to the 4mhz crystals available here as the second harmonice of the 5mhz crystals would fall in the middle of the 30 meter band but the BFO kit mentions choosing the 5mhz crystal for use with the other kits. Can I successfully use the 4mhz crystals?

Would I need just the Gilbert Cell Audio Detector or do I need the BFO kit as well?

Can I change the passband characteristics of the Crystal Filter Kit with different capacitor values. I am curious about the effect of changing the shunt capacitor values and the possibility of using varicap diodes for an adjustable bandwidth. What would you suggest?

Considering the IF amp seems to have excess gain is the wideband preamp either pre/post mixer necessary?

Will the receive path benefit from routing through a low pass filter?

I am learning a great deal from your posts and those of KC0WOX(his videos are tremendous vicarious thrills).

I would encourage anyone lurking to jump in here for the benefit of all.(particularly me)

tnx de
Jim Benson
NS5U/1

ak2b · 2008-12-24 12:56:52

Hi Jim,
Welcome to the group.

jaswarb wrote:
Would I need just the Gilbert Cell Audio Detector or do I need the BFO kit as well?

I think the Gilbert Cell audio Detector with the 4MHz crystal would do just fine. You may or may not have to tweak the values of C4 or C5 - Diz might jump in and answer that. One thing you have going for you is that 4.9Mhz is what Elecraft uses for an IF in all their rigs except the K3. I have all their manuals downloaded for reference. There is a lot of good information there. They use the SA602 as a detector which I don't think is all that different from the SA612.

jaswarb wrote:
Can I change the passband characteristics of the Crystal Filter Kit with different capacitor values? I am curious about the effect of changing the shunt capacitor values and the possibility of using varicap diodes for an adjustable bandwidth. What would you suggest?

Yes, you can choose your capacitors for the passband of your choice. Looking around the forum you will see that I've tried a variety of options - even a variable bandwidth filter. I used 120pf and got a passband of approximately 800 Hz. Diz suggests 470pf for 500Hz. I just got 10 SV149' varactor diodes for a variable crystal filter that I have been experimenting with (they were $0.80 each from Elecraft). I haven't had the chance to try them yet.

jaswarb wrote:
Considering the IF amp seems to have excess gain is the wideband preamp either pre/post mixer necessary?

Diz says he used the amp before the mixer but then he was using the Gilbert Cell mixer which has gain. If you are using the diode ring mixer, which has some loss, I would use it after. I put a 200 ohm pad on the amplifier output to give the crystal filter input a nice non-reactive source to look at. You can wire the amplifier for 50 or 200 ohm output impedance. ~200 ohms is the impedance of the crystal filter. The IF amp does have a lot of gain. On one of my boards I use a variable resistor on pin 5 to control it. I have no agc, but the pot works fine as an IF gain control.

jaswarb wrote:
Will the receive path benefit from routing through a low pass filter?

The benefit of the low pass filter on receive isn't as obvious as it is for transmit. In other words, if you left it out while listening to your receiver you might not hear any difference. On the other hand, it will keep things like VHF interference and other extraneous garbage out of your front end. There are a lot of different front end designs floating around these days for you to pick from. I just tend to lean on the conservative side for the time being and trust what others have done, mainly because I don't know any better . The great thing about using these little boards is that you are not stuck to any one way of doing things. I fully plan to try other designs just as soon as I've understood as much as I can from the present one. I built a W7ZOI/K5IRK 'Progressive Receiver' in the 80's and I guess in my mind this is the correct way to do things. In any case it is interesting to note that the post mixer amplifier that Diz sells is the exact same one as in the Progressive RX - a good, solid, time tested design.

Have fun and please keep us informed of your progress.

Tom, ak2b

ak2b · 2009-01-21 19:49:58

I bought an N2PK VNA and made this *scan of the 15 meter Band Pass Filter with it. I just got this VNA and this is my first scan. I have to admit that I am way over my head with this piece of gear at this point - and to tell the truth, I'm happy to have made this much progress . It is cool that the scan runs fast enough that you can tune in real time and see your progress. Hopefully, in due time, I will be able to test crystal parameters, do impedance measurements and other good things.

Tom, ak2b

*scan revised on 1/24/09 after I reset the proper clock frequency in the VNA Software(steep learning curve )

W4GNS · 2009-01-23 09:53:09

Tom
I would enjoy continued updates on the analyzer. I came very close to ordering a kit this past fall , but at present just don't have the time. Maybe we could talk Papa Diz into a new thread related to stuff not directlt related to the "Dizzy Transceiver" ;-)

ak2b · 2009-01-23 11:59:52

Since I got the analyzer mainly for working with the RF Toolkits (at least for the time being) I will probably post the results I get right here as I go along.
I originally thought I would build the analyzer but when I added up the things I would need, the price kept on growing and growing. Originally hams were saying you could build it for a few hundred dollars but as time went by and the analyzer project grew with things like dual ADC's and USB various clock options, etc., the price climbed up to about $600 for a complete package, if I remember correctly. Anyway, there came a point where confusion over the various versions set in and whether I wanted something to build or something I wanted to use. Building it would have taken up a lot of time and the fear that in the long run it might not work as planned, so, I bought one . http://www.m0wwa.co.uk/page/vna.html It wasn't cheap, slightly over $1K (the British pound has dropped some against the US dollar) but it works and is built beautifully.
Gary, I don't think Diz minds if you or anyone else starts an unrelated topic as long it avoids politics and religion .

W8DIZ · 2009-01-23 14:22:20

ak2b wrote:
Gary, I don't think Diz minds if you or anyone else starts an unrelated topic as long it avoids politics and religion .

Go for it. More stuff to read
-Diz

KitsAndParts.Com Forum

#51 2008-11-29 12:46:09

Re: Erector RX

#52 2008-12-01 17:57:48

Re: Erector RX

#53 2008-12-01 18:14:22

Re: Erector RX

#54 2008-12-01 19:14:27

Re: Erector RX

W8DIZ wrote:

#55 2008-12-01 19:52:04

Re: Erector RX

ak2b wrote:

#56 2008-12-01 21:29:04

Re: Erector RX

ak2b wrote:

#57 2008-12-02 09:05:23

Re: Erector RX

#58 2008-12-02 09:47:43

Re: Erector RX

#59 2008-12-06 16:14:09

Re: Erector RX

#60 2008-12-06 16:55:22

Re: Erector RX

#61 2008-12-08 13:07:31

Re: Erector RX

#62 2008-12-08 13:14:47

Re: Erector RX

ak2b wrote:

#63 2008-12-13 17:48:51

Re: Erector RX

#64 2008-12-14 01:52:41

Re: Erector RX

ak2b wrote:

#65 2008-12-14 09:17:27

Re: Erector RX

#66 2008-12-14 15:45:15

Re: Erector RX

w4gns wrote:

#67 2008-12-15 09:50:49

Re: Erector RX

#68 2008-12-15 11:50:18

Re: Erector RX

ak2b wrote:

#69 2008-12-15 14:45:37

Re: Erector RX

#70 2008-12-24 08:58:24

Re: Erector RX

#71 2008-12-24 12:56:52

Re: Erector RX

jaswarb wrote:

jaswarb wrote:

jaswarb wrote:

jaswarb wrote:

#72 2009-01-21 19:49:58

Re: Erector RX

#73 2009-01-23 09:53:09

Re: Erector RX

#74 2009-01-23 11:59:52

Re: Erector RX

#75 2009-01-23 14:22:20

Re: Erector RX

ak2b wrote:

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