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Showing posts from February, 2019

March 1, 2019 ~ A Digitally Controlled Analog VFO

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A Digitally Controlled Analog VFO.
So OK here is the great reveal on some of the earlier posts on this blog. I built a prototype of a stepper motor controlling the main tuning capacitor of an analog VFO. 
We now have a digitally controlled Analog VFO. This is the first time that I have actually used an Arduino to control a stepper motor. Old hat undoubtedly to many of you; but a first for me with the Arduino. About 10 years ago I dabbled with a project using a PIC16F84. I was totally lost in the Assembly Language.
We will now, some 10 years later, circle back to that old project. It involved the controlling of a remote antenna tuner. This effort with the controlling of the capacitor with a stepper motor is a stepping stone to the Antenna Tuner.
See my website for more details on the VFO, the code to control the stepper motor including the LCD readout and the code for automatic zeroing of the capacitor on power shutdown. It also describes the Antenna Tuner Project approach and how the LCD …

2019 ~ Big DX Contest Coming Up this Weekend

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Big DX Contest This Weekend!
In preparation for the contest I reconfigured one of my 40 Meter rigs so it will work on 20 Meters. It was a pretty simple change over. Unsolder two caps in the BPF and retune the Trimmers and then swap in a pre-made 20M LPF. 

This is the two Filter, two VFO rig with a wooden front panel and of course the cool 20X4 display.
There are quite a few stations in the Caribbean that were testing their stations today. I picked a PJ2, and an HR8 using this rig with an outboard amp at 80 watts. I had my beam in line but can tell it is at times intermittent. I think it is a coax/connector problem at the beam itself. On the list to get fixed ASAP.
What I didn't mention was three lines of code changes, 5 minutes on the computer and I reset the tuning range to 20 Meters. Kind of hard to do with  analog systems unless you have a bunch of heterodyne crystals. 
VFO B defaults to FT8 on startup -- need to test FT8 on 20 Meters. Tomorrow.
The Red knob on the lower right hand s…

2019 ~ A Tale Of Two Hams

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Two variations on the same theme.2/27/2019 ~ Simple is Better!
 Several off and on blog comments has caused me to think (something I should have done more of sooner). 


My main issue was to "assure an automatic "ZEROING" of a circuit which led me down a path of trying to store a register value in EEPROM should I forget to manually Zero a control before power turn off. This quickly got complex. Then N8MN described to me how he used something I developed for an LDMOS amp control circuit to essentially do the same thing. Other commenters suggested a similar approach.


But then in a lightning moment at 3;00 AM this morning my brain said STOP!. You don't need to screw with the EEPROM! What I am trying to do is ZERO a control before the power goes off (either manually or automatically). When you power off the circuit logic takes over to automatically introduce a delay while the control is Zeroed and then power shut off. A bonus --some logic in there to provide reverse voltage …

2019 ~ Building SSB Transceivers

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The Building of a SSB Transceiver ~ You can do it!2/22/2019 At Christmas my 3rd son gave me a transducer speaker that mounts to a piece of foam board and I sit here amazed at the sound reproduction. The amp driving the speaker is the 2N3904 and LM386. So it will provide more than just headphone volume (with a 100 Ohm resistor installed). I received a comment about the 100 Ohm resistor and just for fun substituted a 10 Ohm in the LT Spice simulation and saw no difference in the output curves. The short video tells much.


Pete, N6QW

2/21/2019 ~ Go Daddy Now Fixed! The audio Amp Schematic is on the website.
2/20/2019 ~ Problems with Go Daddy!!
For over 24 hours I have been trying to upload updated schematics and information to my n6qw website. It seems like Go Daddy who hosts my website has some sort of issue with a windows server. One solution that offered was for me to spend more money and move over to a Linux server OR just wait until they get around to fixing the problem. Not only is it a …

2019 ~ Retrofitting Old Boat Anchors with New Technology

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Turning an Old Boat Anchor into a Silk Purse. Yes it involves the Arduino!!!!
I frequently tour eBay looking for bargain "Boat Anchors" that can be easily retrofitted to work the bands with rock solid frequency stability. Most of these old boat anchors suffer from drifting "ANALOG" VFO's. Yesterday I came close to acquiring such a rig. Early on Yaesu marketed some rigs that pre-date the highly successful FT-101 series of transceivers.
One such model is the FTdx-100 and I had one of those about 7 years ago and you can see how I "worked on that rig" on my website www.jessystems.com. Recently I spotted a Sommerkamp FT-100, virtually the same gear marketed by Sommerkamp in Germany along about 1966.


My complaint about the FTdx-100 was that it lacked DFMA.

[ For those who did not spend half their life in aerospace manufacturing DFMA is defined as Designed For Manufacturing & Assembly. Bottom Line you can service what you build without a total disassembly of…

2019 ~ Lets Be Safe as we Pursue our Wonderful Hobby!

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Listen to Pete!