Archive for the ‘Test Equipment’ Category

8640-jr Final

April 2, 2015


Well, I had it wrong…the pin-outs were as the datasheets showed. But I had to actually draw a picture of the device (both top and bottom view) to convince myself of what I was seeing. Long story short, it works as it should and I am happy with the results.

Here is a pic of the PCB of the VFO and a pic of the output from T1 on my scope.

VFO PCB

T1 Output

 

The power out at 13 MHz is 640 mv peak to peak and 412 mv at 32 MHz. I was surprised that the second harmonic was way down in the noise floor, barely noticeable.

Again, this as part of a project that Todd, VE7BPO proposed back in the winter months as a two part article for the Michigan QRP Club’s quarterly publication called the T5W. Todd did the first article that featured the divider portion of the project that follows this VFO. In a nutshell, the VFO produces a signal source from 13 to 31 MHz. The 20 meter segment is analog and the 40 and 80 meters segments are produced by the digital portions of the project by dividing the analog signal by two and four respectively.

This project was originally conceived by Wes, W7ZOI…and reproduced my many others to follow him.  Though this project falls short in producing a lab grade signal generator, it does provide a great signal source for 3.5 to 30 MHz and can come in handy in the shack and on the workbench.  My thanks to Todd for suggesting this project…I learned a lot and had a lot of fun getting there!

 

 

 

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8640-jr Update #1

March 30, 2015

Well, I ran into a road block this afternoon that took some time to sort out. I built the FET VFO and Follower (for isolation) portions of the VFO…but could not get it to oscillate. After checking wiring and voltages, I pulled another 2N4416A from the junk box and checked it with my M-Cubed semiconductor checker. I noticed that it showed the DRAIN and SOURCE pins reversed from what the datasheet indicated. I rebuilt the two stages using the info that the M-Cubed checker showed me and the VFO worked. I got these 2N4416A’s from a reputable USA company but now wonder if maybe they were clones from an overseas location. Bottom line…never assume anything, always check and measure everything.

Have the BUFFER AMP to build and then do some tweaking and final measurements. This project is a joint effort of Todd, VE7BPO and myself for an article for the Michigan QRP Club’s quarterly publication called “The 5 Watter” (T5W). Todd suggested this article during the winter months and it has been a fun adventure so far.  I sort of got side tracked this last month and just now am getting back on track with the project.  The original 8640-jr project was done by Wes, W7ZOI…it is a three band VFO that develops a 13 to 30 MHz signal which is then ran through a couple of dividers to result in 3.5, 7 and 14 MHz VFO signal source or can be configured to run from 3.4 to 31 MHz as a signal generator.

Always fun to snuff solder fumes and figure out why things don’t work the first time as planned <smile>.

8640-jr VFO

March 29, 2015

Started assembling a 8640-jr VFO tonight. Should have done this a month ago but been rather busy with no-related bench stuff lately. Built and tested the +6 volt strip and now onto the oscillator and buffer stages.

Located and sorted the parts for the entire project…now just need to build it, then test and measure the three stages. This is for a T5W article that VE7BPO inspired a couple of months ago.

Recovering from FDIM/Hamvention

May 21, 2014

Have about recovered from the trip to Dayton. Rained the entire time except Sunday and Monday (the day we came home) and quite cool. But, if you don’t have to like the weather to enjoy it at Dayton. We stay at the KOA campground every year and love the friendships we have made the there.

As far as what goodies I bought…some 2.5″x3.0″ prototyping boards at a dollar a piece (good deal), an interface for my MFJ-259B so I can plot my sweeps on the PC, and finally broke down and bought the DSA815-TG spectrum analyzer. I have been struggling about buying one for over a year…so made the plunge. I have been playing with it for a few days now and makes me wonder how I ever got along without it! I put it next to my DS1052E scope and was able to remove several pieces of older test equipment that I won’t need anymore on the bench. Also picked up a hiking pack for three to four day trips on the trails.

I hope to get back to the Binuaral Receiver in a day or two. I am anxious to use the new SA on it and see how clean the crystal resonator really is. If it is clean, I will use those prototyping boards and make both 40 meter and a 80 meter resonators for the work bench.

Update on PHSNA

March 23, 2014

Todd, VE7BPO has posted some pictures of my PHSNA system on his web site. Look near the end of section 1 at http://www.qrp.pops.net/sundry12.asp  (with a sub-title of QRP-POSDATA for March 2014  — Poor Hams Scalar Network Analyzer  (PHSNA) – ) for a look at the pictures. I am now playing with some software written by Nick, WA5BDU that incorporates many of the newer functions!

72/73…Mikey, WB8ICN

Winter Updates

March 5, 2014

Been doing some bench work, though I am still not doing a good job of posting my work here. Built a SNA using an Arduino, DDS module, and a W7ZOI power detector. The web site for this project is located at https://groups.yahoo.com/neo/groups/PHSNA/info and is a fun project. I had a RLB I built a few year ago, but just finished another one from a kit offered by the same group that offered the SNA. I ended up with a bridge directivity of a bit over 35 dB, which is pretty good. I sweep my YAGI beam and had about the same result as with my previous homebrewed RLB. Below is the sweep using my old RLB

Yagi Sweep 13 to 30 MHz Chart (1)

 

 

 

 

I have built and sweep several LPFs, BPFs, and crystals. My next endeavor is sweep components to see the response compared to frequency. Should be interesting.

That is it for now. Been the coldest winter I can remember here and have used the electric heater in the shack here in the basement more than I care to admit…the electric bill really shows it when I do this for an extended period of time. We have had weeks at a time without ever getting above the freezing mark of 32 degrees (F), and many nights and a few days of below zero temps. Thinking that maybe next winter we might go south and try to get sun tans during the winter months <smile>.

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…

Turkey Day Update

November 24, 2011

Been working on understanding Return Loss (RL) and also various ways to use a return loss bridge (RLB). Todd, VE7BPO and his RF Workbench series are a great help in learning to make meaningful measurements in a 50 Ohm environment. Now a lot of the equations I have read about are making sense and the numbers are something I can use.

Took a break and built a five-switch 95dB attenuator this evening to use for our local transmitter hunts. Between my homebrewed W7ZOI spectrum analyzer (SA) and my M-Cubed Freq/PWR meter, I verified all the switches and how it performs at 147MHz. Wish the SA would reach up to the VHF, but only goes to about 90 MHz. But, between the SA and the power meter, I was able to satisfy myself that the attenuator does what I want it to do.

Tomorrow is Thanksgiving, so here is wishing all of you a very happy and joyful day. I have many things to thankful for and look forward to eating and playing in the shack later on.