Archive for the ‘QRP’ Category

KX1 Upgrades

December 4, 2014

I have been adding to my Elecraft KX1 rig. Added the 30 meter mod and as of tonight, have built and installed the ATU mod. I plan on using the KX1 while we are in the RV and having the ATU is a definite plus with a non-resonant antenna. I received the Ten Tec Rebel rig last week. Checked it out and all seems fine, but have to wait till Christmas morning before Santa will let me play with it. But, this will be a big part of what I plan on doing this winter…ARDUINO learning!

I do have some Arduino projects I might start now that all the outside work/chores are done. I do want to try to use an Arduino for a CW decoding project. Have seen a couple of blogs that have done some work in this area, so I won’t have to start from scratch.

The weather in November was quite an eye-opener for most of the northern part of Michigan…but December has proven to be quite tame and I hope it stays that way. I might even try to get some antenna projects launched if the current temperature trend continues.

That’s it for now…stay tuned.

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Relook at Measurements…

June 21, 2014

Well, found that a bad scope probe can be a big problem when trying to understand things…LOL.  Since replacing the bad probe, I discovered that the LO is working fine, have just over a volt coming out and going to the Product Detector. The RF input section still bothers me but it seems to be working as it should. However, the RF Phase Shift inductor (molded inductor) may be a problem, so after looking at things, I am going to take Mark’s advice and try a torroid. This may help recover some gain I seem to be losing. I get a three fold gain in voltage (317mv input/922mv output) from the RF Amp…but this varies as the input signal decreases in amplitude.

I have thought about incorporating some type of feedback for the RF Amp section to help maintain the RF level from the input to the Product Detector. I can hear a signal with -50 dBm input, but any less than that and I lose all AF going to a speaker/headphone. I should be able to use half that value of input signal and still hear a signal. I am thinking after I try swapping a torroid for the molded inductor, I may switch to a single signal type detector or pop a NE602 in-place of the current front end and see what I get. Since I wouldn’t be able to hear the binuaral effect anyway (due to being deaf in one ear), I might as well move on and try other ideas.

I built a 40 meter NE602 receiver a number of years ago and it was fun and simple. I may use the LO from this project and incorporate that receiver into a single signal receiver. I want to make up one 80 meter LO and one 40 meter LO on separate PCB boards to have on the bench for future use. All in all, this has been a fun  and thought provoking exercise. I need to keep a focus on little things that can affect the overall success of the project (Thanks Mark of helping me learn this!), and remember to check my measurement methods to ensure they are sound and accurate.

I will probably have one more update after this and then move on to another project involving a remote terminal for my PHSNA.

Corrections/Update

June 20, 2014

Been wrapped up in a bunch of chores/Honey-Do’s/etc and haven’t had much time to spend at the bench. Finally got back at it tonight and rechecked some measurements I did earlier on the LO and RF portion of the receiver project…and they do not match what I had recorded earlier.

Since the forecast is for rain all day tomorrow, I hope to remeasure everything and re-evaluate what I have so far and where to go from here. Since I am deaf in one ear…making a binaural receiver makes little sense. Have been thinking of changing directions with this project since the LO was the main interest when I started this whole thing. Thinking of rewiring the front end and using a NE602 to see what that produces…and spend some more time with the current product detector to better understand it.

A special thanks goes out to Mark Dunning from down-under who has pointed out some items I overlooked…and in general made me reconsider just what I am doing and where I might go with this. Its always better to have an extra pair of eyes and a second opinion to help one focus on what they are doing!

Binaural Receiver Update

June 7, 2014

Well, wired up one stage of the AF section (which provided one earphone worth of audio). Using my sig gen I could hear and tune above and below the signal…but that is with about zero dBm of input signal. When I connected the project to a 40 meter antenna, I heard nothing!

Need to check the Input RF Preamp and see if it is working. There were enough 40 meter CW signals on the air tonight that I should have heard something. I may have to add a RF amp to the front end if everything else is working as it should.

The RF Phase Splitter is working as I can turn it all the one way and have lots of audio when using the sig gen for an input, and then when turned all the other way, have nothing. I am not going to build the second AF section until I determine what or why I cannot hear any 40 meter CW signals.

 

Stay tuned!

Binaural Receiver for 40 Meters

May 5, 2014

Started a new project.  It is taken from the the Lo-Key magazine, number 121, March 2014. It is published by the VK QRP Club from down under, and the article is by Peter Parker, VK3YE.  Actually it started out wanting to play with a ceramic resonator oscillator and this receiver had one.  So I built the oscillator first…it worked first time and I am quite happy with the results thus far. It was to be for 40 meters…but found that it will oscillate on both 40 and 80 meters, so thinking I may end up with a dual-band binaural receiver. Will have to build a second LPF for the input…and I need to look into the RF Shifting network to see if it is frequency sensitive.

Here is the schematic:

Ceramic Resonator Osc-jpg

 

 

 

 

 

 

 

 

 

The range of tuning is from 6.978 MHz to 7.295 MHz. I am only interested in 7.0 to 7.18 MHz…primarily the CW portion of the 40 meter band. The tuning capacitor needed turned out to be only 250 to 30 pf (7.0 to 7.18 MHz respectively).  The LO signal level is 3.3 dbm at 7 MHz and drops only to 2.5 dBm at 7.18 MHz.

I found out that the oscillator will also put out a signal from 3.47 MHz to 3.627 MHz…and the LO signal level is 4.5 to 3.7 dBm.  Considering the capacitance swing needed, I can use a simple polyvaricon  (Nine Volt Transistor Radio variable capacitor type) for the tuning capacitor.

We are getting our RV ready for our annual trek to Dayton for FDIM/Hamvention in a couple of weeks, so not sure how much of this project will get done till we get back… but it has been fun  so far.  I want to play with the oscillator a bit before I move on with the rest of the receiver.  I used molded inductors to make the 3.3 uh tuning inductor and want to try a roid and then try the whole circuit with the small variable capacitor.

Enjoying the bench time and snuffing solder fumes. It was so cold this winter and the shack/workbench are in the unheated basement…so needless to say, I spent less time this winter down here than I had hoped too.  Either I have to move the shack/workbench upstairs or come up with some sort of heating that is affordable when the outside temps tend to stay below 32 degrees (if not below zero) for days and weeks at a time!

 

Fall 2013 Update

September 28, 2013

Had a great summer camping (RVing with our fifth-wheel), but the leaves are starting to fall so guess its time to put the RV under the cover and start playing on the workbench and getting back on the air.

Want to finish playing with the vertical antenna ideas for our RV, then start playing with some of the new microcontroller boards I have gotten over the summer. Have found many ham radio related Arduino projects so guess that will be first on my list of things to do. Have to yet to build the PTO for my 4SQRP kit so that is a “must do” in the month of October. Also want to do some playing around with some test equipment ideas that have been floating around in my head. Going to be a busy winter. The forecast is for more snow than average so will not be going out to sun-bath much in the next few months.

Have several QRP rigs I have built but have not used in quite awhile…so plan on doing the musical chair thing and play with them this winter also. Maybe it is time to sell some of these older rigs and keep just a couple for me…stay tuned for the result of that decision.  Drop me a line at wb8icn@gmail.com if you have any ideas/projects that you might want to share.

FDIM, Hamvention, KX1

May 25, 2013

Well, as they say, FDIM/Hamvention is in the history books. We camped at the KOA with about 200+ hams and had a very enjoyable time. I think I go now to Dayton for the social aspects of FDIM and Hamvention, whereas years ago it was to find bargains and new kits. I did buy the new 40 xcvr from the 4SQRP gang…it is called a Cyclone and uses a neat version of a PTO VFO. The case is made of the same material as the PCB, so that will be a new one for me. I also bought the RF Section (8554B) for the HP spectrum analyzer that I had but without a working RF Section. Also found a blue LCD shield for the arduino microprocessor board. All in all, the trip was very good even though there were a few days of cool weather while we were camping just north of Dayton and then some rainy weather at Shipshewanne.

I made my first contact using my KX1. Was on 40 meters and worked Bill, W9VC down in Richmond. IN. Bill has a very good first and it was fun to chat with him.

I tried operating the first part of the week while at Dayton, but some X-Class flares on Monday and Tuesday (prior to FDIM/Hamvention) made band conditions unworkable. I had to want to give my new end-fed antenna a work out, but that did not pan out. We are going to NY next month for some fishing and visit the XYL’s family, so will try again then.

I am listening the the CQ WW WPX CW contest right now with the KX1 and have found that the variable receive filter is worth its weight in gold. I really like being able to adjust the bandwidth on the fly when conditions get crowded. I can adjust from 0.3 to 2.0 KHz and it makes copying so enjoyable! Guess the KX1 and K1 will both be in my camping box for the summer…hi hi.

That is about it for now. Trying to get some yard work done this weekend before I doing some bass fishing next week, so solder fumes and dit/dahs are on hold for the moment.

Stay tuned for how my antenna experiments go this summer with the RV…

End-Feed Antenna is Finished…

April 23, 2013

Finished the end-fed antenna for the RV today. I ended up taking off about four feet of the wire so the antenna is about 26 feet long. SWR using my K1 with auto tuner is as follows:

40 meters = 1.3 to 1
30 meters = 1.1 to 1
20 meters = 1.0 to 1
15 meters = 1.0 to 1

Sent CQ on 7031 KHz and N9OL in Evansville, IN (386 miles to the SW) answered and we had a short QRP QSO. I was running 4 watts and John was running 5 watts. Things were fine till three other stations crowded in and I lost John in the ensuing chaos. My end-fed is mounted as a sloper and should have favored the NW…but our trips RV’ing this summer will tell more on this.

The antenna is short enough to fit in the foot print of my fifth-wheel RV. I use my awning as the tie-point for the UNUN and coax. If I don’t have the awning up, I can always just use a stake or short pole to hook the UNUN and coax to.

This antenna was the brain-storm of the fine folks at http://www.earchi.org and is their end fed 6 – 40 meter multiband HF antenna. I followed their article and ended up with a great antenna for my RV. Anyone who is space limited as far as antennas are concerned, ought to check out this antenna. They also tell how to make a “No tuner needed” 20 and 40 meter end-fed antennas. The 6 thru 40 meter antenna does require a tuner.

CC & KX1

April 11, 2013

Made a couple of contacts with the CC1 but have not yet attempted to measure and drill the front and back panels for the case.

The KX1 arrived today. A tad over 4 watts out on both 40 and 20 meters and the receive sounds fantastic! The KX1 may become my new QRP camping rig. I have the 30 meter option for the KX1…if I install it, it will be the same as my K1. Been raining here for several days now…if it ever stops, I can start playing with the antenna ideas I have for the RV.

Being retired is both busy and hard work…LOL!!!

Workbench Progress

April 10, 2013

OK, the KX1 is done…the firmware chip was bad but thanks to the KX1 guru Don, W3FPR, that along with a couple of solder reflows and he got the rig working. The guy really knows his stuff! The KX1 should be back here in a week or so and then I can try it out.

Completed the beta build on Etherkit’s new CC1 40 meter transceiver…nearly all smd and challenging for an old fart like me. But had fun, though I may hesitate from future smd projects unless they are size 1206…better yet, stick with thru-hole components…LOL. Made a couple of contacts this evening as is and it works rather well.  2.5 watts out and the receiver is really hot! I have yet to tackle the case which is included but not marked so I have to do some measuring and praying (!!!) to get it right.

We have uncovered our fifth wheel and I want to start playing with some antenna ideas to use this season while out and about…camping/fishing/QRP operation, it just don’t get any better than that!