Skip to main content

Simpleceiver ~ Part 23

Revisions to the Simpleceiver Detector

 
We are delighted to see that there are homebrewer's out there who are building this project and that is most gratifying. This gives me a sense that all of the time I spend developing circuits and maintaining this blog is having some impact and benefit to the greater ham community.
 
In an exchange of emails with Bob, K6GGO, who built the product detector with the intent of having an 8.0 MHz IF, he reported that he physically built the circuit and ran some test to characterize the performance. His conclusion was that the circuit performed nicely but was seeing an output response capability that extended beyond 100 kHz and in fact had seen a peak response closer to 200 kHz.
 
My response to Bob was that I had seen the same thing but simply ignored anything beyond 20 kHz as this was AUDIO and anything beyond that would never be heard by humans --maybe your dog would hear it? So in the interest of those who would have sleepless nights knowing that the output from their product detector could support  a frequency response output beyond the audio range, I did some further evaluations.
 
Using LT Spice it was a simple matter of making some trial runs to see the effect of changes. Basically I used the Direct Conversion Receiver to test the part change but the same change is made in the Product Detector circuit in he Superhet version.

I am happy to report there will be no output or peak response beyond the audio range and thus those who may suffer a sleepless night will have a peaceful rest. One component value change did the trick. L1 which is in the output filter network is changed from 1000 uHy to 100000 uHy. (For the old school guys like me that s 1 Milli Henry to 100 Milli Henry). I am delighted to report that 100 Milli Henry chokes may be acquired from Mouser  100MHy Choke The cost is a staggering 38 Cents.

 
 
 
 
There is much good in collaboration and having an openness to making changes. One part value change = peaceful sleep!
 
73's
Pete N6QW
 

Popular posts from this blog

January 26, 2024. A simple CW Transceiver/Transmitter

Cruise through the lower part of the ham bands bands and what do you hear? Well, FT-8 and CW. Often you will not hear any SSB stations yet go to the lower part of the bands, and it is a cacophony (I love that word) of bad sounding signals and some high-speed keying. Fast is not so much of the issue as is bad, run together and jerky keying. But none the less our hobby started there.    So, you could crank down your ICOM 7300 and watch the waterfall on CW or you could homebrew a radio. Actually, to do CW right you need more thought up front than you do with a SSB transceiver. Often, I will state that a CW Transceiver is much more difficult to build than a simple SSB rig. I published two articles in QRP Quarterly on CW transceivers and all I got was a yawn so maybe history will repeat itself.  Yawn!   30M CW Transceiver with RIT!   Of interest is that the LO is a Varactor tuned LC oscillator using a NE602. Look closely at the RIT circuit which is only activated on ...
Read more

August 30, 2024. A PNP 20M SSB Transceiver

Shown below is the Block Diagram for the 20M PNP SSB Transceiver steered in the  Transmit Mode . The components shown in the dotted block are relay steered so that the block module is single pass and amplifies in a single direction. The Block diagram show steered in Transmit.  Essentially the steering process works so that the IF Module input follows the Balanced Modulator on Transmit and then the input side follows the Receive Mixer on Receive. All done with some relays and a bit of RG174U coax. For those who count things in detail, this block diagram is not unlike what was used for the PSSST Transceiver which can be found on my website . Yes, a warmed over P3ST only using PNP devices. TYGNYBNT. 73's Pete N6QW
Read more

March 31, 2024. Happy Easter to those who celebrate this day.

What a great day to Binge on Chocolate and experience the pain of that filling that has been leaking.  I would be in that category with the leaking filling(s) had I not just spent an amount equivalent to one of the fancy new uptown appliance box transceivers on two filling repairs. Well at least I can binge on the Chocolate bunnies without fear of pain. Regrettably everything appears to have jumped in price including the price of parts. Well not so much the parts as the shipping costs.  That notably is seen in the eBay treasures. I spotted a nice heathkit DX-20 for about $50 and the shipping was $65. Likely it is a twofer with part being a way to in effect charge a higher price by inflating the shipping and in part by increased shipping costs. Shipping with insurance across the US was about $150 for this jewel and that was three years ago. 6AM on the Left Coast ~ 20M Easter Sunday! My only hope is the cost of Chocolate Bunnies remains steady although a pound of See's Candies f...
Read more