The Next Project a DSB Transceiver!
2nd Series of Tests of the MC1496 DSB Generator 7/11/2021
The Carrier Input Level is on the Critical Path and Affects Carrier Suppression!
Pete N6QW
Some Pasta Pete photos from the 4th of July Cookout! This was Dinner for 4.5 (Four Adults plus my 8 month old Granddaughter. She had some of the grilled Salmon and enjoyed it using her new two front teeth!)
A link to a Compendium of Information on DSB Transmitters from N2CQR
So Ok you lack skills and lack experience in building stuff ! Thusly, here is your chance to overcome those shortcomings by building a simple VOICE transceiver only it is double sideband. Think of it as an AM Signal with no carrier.
Double Sideband (DSB) is an authorized form of amateur transmission and so rebuff any claims from the FLEX guys that you can't use that radio here -- to the contrary -- it can be used any place where phone operation is authorized! They are just plain jealous that they had to spend $6K to put out a signal and you had to spend a small fraction of that sum.
The beauty of such a rig is that there are few components and such a DSB transceiver builds upon the N6QW Direct Conversion Receiver found in SPRAT 187. You already have the most critical part and that is the LO which makes it rock steady and avoids the criticism that you are drifting. Here is the link to the project N6QW DCR/DSB
The DSB Transmitter topology is in work and will be under test here in the real near term -- like maybe today. Today is Here!
The heart of the DSB Generator is an MC1496, available from Amazon in leaded form and Mouser in SMD with total unit cost at either source for less than $1.
The other piece the microphone amplifier is a 2N3904. I have built my DSB generator on a piece of single sided copper vector board and the size is 2" X 2". Following that will be a BPF and a couple of amplifier stages and a W3NQN LPF.
For good measure and for the anal retentive nerds who worry about such things, we could follow the mic amp with an 3 kHz wide audio filter such as those used by KK7B in the R2 and T2. At this stage I do not believe it is necessary. I am just trying to head off the emails from those who never have built stuff and see this as a Gotcha!
For those about to email me about using the NE602 --don't waste the keystrokes. You want an NE602 then have at it. Look at the cost -- NE602's costs a lot more than $1 and there is virtually no performance advantage. This transceiver will have two MC1496's with one in the Rx and the other in a Tx.
Now we must be good hams and think and act responsibly about the following.
You are putting out two sidebands --so refrain from connecting this to a KW amp -- a 1KW USB signal on 40M might not be appreciated. So keep it QRP at 5 watts with an IRF510 for the final. You will make many contacts!
The power spectrum issue drives a second consideration of a watering hole frequency. Already there is a 40M QRP SSB frequency and that is 7.285 Mhz. So if we operated on DSB on 7.285 --there will be less CRAP [CRAP = Constant Ragging And Poking] from the FLEX Radio Police.
Finally keep in mind out of band operation: while one Sideband may be In Band the other may not be in the event you are working very close to the band edges.
About 6 months ago I made my 1st ever 12 Meter Contact using 5 watts. So the higher frequency bands are like a lady in heat! I would avoid 20 Meters; but certainly 17 Meters would be ripe for the pickings at 18.130 MHz. In case so inclined 20M SSB QRP is 14.285 MHz.
In due course I will provide some schematics --but you could do a bit of research by visiting Google and You Tube. Peter Parker, VK3YE has quite a few DSB you-tube videos and is an excellent resource.
Stay tuned for more opportunities to harass the FLEX Radio 40M Radio Police.
73's
Pete N6QW
If you are not a member of the GQRP Club, then you are wrong!
[See the Latest Video Embed 7/8/2021]
This is the front cover of SPRAT 187, a Publication of the GQRP Club. Having a project on the front cover of SPRAT is significant and is akin in the ham radio world to having your face, band, or boobs on the cover of Rolling Stone Magazine. Shamelessly it is my project and so I am on the cover!
The article covers a Direct Conversion Receiver (DCR) that by the estimation and comment from many who have built the DCR is "Jaw Dropping" in terms of simplicity and outstanding performance. The basic innards are but one IC the MC1496, Double Balanced Mixer. The other "HUGE Bonus" no drifty analog LO. If you have not taken the leap to the digital VFO using the Arduino and Si5351, this is your opportunity!
A "Stop Order" to those of you that have never built anything, who are about to pen me an email telling me why the NE602 is so much better. I don't care to receive your email and this is not about comparing Double Balanced Mixers.
It is however, an application of the MC1496 that has been around so long it qualifies for membership in the AARP. Check out commercial ham equipment built in the 1970's/80's and typically you will see an MC1496 in the design with often several being used. If you check what I call the Ham Radio Bible (Not EMRFD), Solid State Design for the Radio Amateur, many of the projects are built around this device. Check out pp 203-205.
The MC1496 can be purchased in the SMD configuration from Mouser and in the leaded configuration from Amazon. In both sources, the unit cost is less than $1.
[A word of caution -- the myriad of older MC1496 designs use the 10 Pin metal TO-5 sized device. The current configurations (SMD or leaded) use the 14 Pin DIP. There is not a total pin for pin compatibility --so if you are using a schematic for a project that was built around the TO-5 but you wired it with the 14 Pin DIP -- that means I will get the usual email "your design sucks" -- no it doesn't suck; but it is that you failed to heed this caution.]
So you are not a member of the GQRP Club (that is too bad); but you can follow the project here Of note is that within that link is a further link to two hams in the UK who have built this DCR and they have much added technical information and alternative construction methods including Gerber Files so you can make boards at home.
Now being a radio genius I have it arranged that you must contact me to get the Arduino code. This affords me several pieces of data. I get a rough number of hams looking to build the project and it also gives me market penetration and segmentation data.
So OK there have been over 60 requests for the code so far with half of those coming from the UK which tracks that the bulk of members are in the UK. I have also found out that several were built without contacting me for the code. So that is another plus for the project -- any old code will work. But the input from one of these builders was "jaw dropping" which adds to the other jaw dropping comments.
When you visit the link there are several embedded you tube videos where you too can experience "jaw dropping".
Just so you fully appreciate the Left Coast life style, I received this advert in the mail last week. Note: Woodland Hills (the Drive Thru Location) is but a short jaunt from my QTH and an alternative "Hollywood" enclave. The Motion Picture's Retirement Home is also located here!
(Am still wondering why I was in the targeted ad mail group. Firstly, I don't smoke and secondly I don't use POT!)
Rock On! Do Not Let World Events harsh your mellow!
73'sPete N6QW
