Category: BITX40Module

A Charming Detail About the BITX40 Module

In the BITX20 yahoo group, Farhan responded to a question about the BFO and the crystal filter in the BITX 40 Modules. In his response we learn more about the work of the members of the women’s collective. Uma is the name of the lady who has the job of sorting the crystals. She sorts 1000 a day:

Farhan writes:
There is a longer explanation to this. The crystals we use in the BITX are microprocessor grade. This means that they are not very precise. Uma is the crystal sorter. She takes a bunch of 1000 crystals a day and sorts them by their frequency into different bags. Each board takes its five crystals from any one bag. Hence, the central frequency of each board will be slightly different from another board.

The central frequency of the ladder filter moves down from the oscillating frequency of the same crystal. That is why, in a set of matched crystals, one can be directly used as the carrier/beat frequency oscillator without needing any trimmer : it directly sits on the higher side skirt of the filter.

The BITX40 board’s BFO usually ranges from 11.990.0 to 11.997.0, though in almost all cases it is very close to 11.998.0. The best way to determine the BFO frequency is to take it another ham’s shack, tune in the BFO to zero beat on USB or LSB and note the frequency. I use the Rigol scope’s built-in frequency counter to measure it off the modulator transformer’s primary.

So, the IF offset should ideally set to the measured BFO’s frequency. These are however, very subjective choices. Given that 2.2 KHz is not an ideal passband, 3 KHz is more like it, setting the BFO will determine how you would like to hear the receiver. Setting it close to the passband will make it bassy, setting it away will make it tinny. Setting it a few hundred hertz away will make it hollow. You get to choose which way you want to make your radio sound bad (harr! harr!)

– f

TRGHS! HB2HB! Homebrew Extravaganza on 40 Meters!

AC7M HB Amp and HB Power Supply
I was flying solo last night. Everyone else in the house was out. So I turned to ham radio for some company. And I was rewarded.


I called CQ with my BITX DIGI-TIA rig and was immediately answered by Doc AC7M in far-off Twin Peaks, Idaho. Doc was running a K3 to a homebrew solid state full gallon amp. And get this — Doc had also homebrewed the 3 kw switching power supply. I looked at my store-bought supply and felt like an appliance operator. I hang my head in shame.

As we discussed solid state amplifiers, we were joined by another builder of silicon after-burners: Don K9AQ, who called in from a beautiful cabin in rural Wisconsin. Don’s amp is based on the venerable EB-104 design.

Both Don and Doc talked about the work of W6PQL. He has a really amazing site devoted to homebrew solid stat amps, and he is selling lots of great boards and parts for this kind of project:
http://www.w6pql.com/

As I finishing up with Don and Doc, I got a very welcome call from an old friend from the SolderSmoke community: Dino KL0S. He as booming in from Williamsburg, Va. Dino has an amazing workshop. He is building a serious vertical antenna for 160 meters. Dino is going for the DX.

Dino’s Bench


At this point Mike WA3O in Pittsburgh called in. And get this: Mike heard me on his new BITX 40 Module. The Radio Gods Have Spoken! (TRGHS!). We switched up to 7.285 MHz where I fired up my BITX 40 Module for a BITX40-BITX40 QSO (albeit not at QRP levels).
We should definitely make more use of 7.285 for BITX40 and other HB QRP SSB QSOs. 1930 EST (0030 Z) seems like a good time.

Finally, just when I was thinking that things couldn’t get any better, they did: Armand WA1UQO called in from Richmond. Armand and I collaborate on parts acquisition at Virginia hamfests. We specialize in the contents of the musty cardboard boxes found under the tables. We discussed the DISRUPTIVE influence of Farhan’s BITX 40: All around the world, other homebrew projects are being literally pushed aside on workbenches to make room for that fantastic little module from Hyderabad.

I was very pleased to hear that Armand is building an analog VFO for his module, using a coil in the 4 uH range, wound on a piece of cardboard tube from a coathanger. The inspiration for this kind of coil (which I now have in THREE rigs) came from Farhan, who used sipping straws from fast-food restaurants as coil forms in a sig generator that he built years ago. This week, seeing a Facebook picture of my daughter and me in a restaurant with drinking glasses in front of us, Farhan asked if I had brought home the straws.

Moonbounce on 40

Well, we were talking about it on 40. This just proves that there is more to 40 meter SSB than the never-ending quest for audio “brilliance,” “presence,” “body” and “sparkle.” I was working at the bench yesterday when I heard Frank NC1I telling another fellow about his 35 years of experience with moonbounce. Wow, you don’t hear that kind of talk on 40 every day. Frank also said that the contact I was listening to was one of very few HF contacts that he has made in recent years. I just had to jump in to encourage him to get on 40 more regularly. He seemed impressed with my BITX40 Module (which I was using). I warned him of the buffoonery that can be found on the band, but told him not to be deterred by it — there are a lot of FB hams on 40.

Above you can see Frank’s amazing antenna farm. The dish is for 23 cm EME. Behind the you can see his 70 cm array. That is 48 (FORTY EIGHT!) end-mounted Yagis, aimed into space.

Check out Frank’s QRZ.com page: http://www.qrz.com/db/NC1I He has some great pictures of his shack. In case you are wondering why he has so many rotator control boxes, remember that the dish and the Yagi array need two each (azimuth AND elevation).

HB2HB: Butch K0BS with a KWM2 and a Hombrew 4-1000 Amp

Wow! Now THAT is a shack! This morning I heard Butch K0BS and his friends on 40 meter SSB. I knew I was listening to the voices of kindred spirits when I heard them talk about a drifting VFO and the need to heat up the filaments of an ART-13. As the group was shutting down to begin their preparations for Thanksgiving dinners, I gave Bruce a call with my BITX 40 Module. He was on a KWM-2 (the rig that had been drifting a bit) and a homebrew 4-1000 amplifier. I told him that I think a bit of VFO drift is a sign of good character.

You really need to check out the pictures on Bruce’s QRZ.com page:

https://www.qrz.com/db/K0BS

 Happy Thanksgiving to all who are celebrating the holiday.

Analog TO THE MAX! An Old School Readout for the BITX 40

Perhaps this was a reaction to a frustrating morning spent trying to get a 20×4 digital display to work with an Si5351 and an Arduino Uno via an I2C bus (I feel my blood pressure rising just due to the typing of those words). After much digital fiddling, I declared a “BASTA!” and looked around the shack for an antidote for the digital frustration. There on the bench was my fully analog BITX40Module rig, with its homebrew L-C analog VFO. It needed a better frequency readout. And this morning, it got one.

The pointer is Sharpie ink on a bit of PC board. It is held in place by superglue, suspended by a piece of wood about 1/4 inch off the chassis (to reduce dial parallax). The numerals are in Dymo tape — there was not enough room for the “7” but I think I will be able to remember this.

Very therapeutic and satisfying.

Putting a Heatsink on the BITX40 Module

The fan that I installed yesterday was driving me nuts. It was noisy, both acoustically and electrically. And I would occasionally get my fingers in the blades. Not good. While it did seem to keep the IRF510 from getting too hot, I knew that a real heatsink would do better thermally.

But how was I going to attach the sink to the transistor? That tab on the IRF510 goes to the collector, so if it touches a grounded heat sink, you get a short. A nylon screw and some mylar between the transistor tab and the heat sink is one option. But I didn’t have a nylon screw. So I decided to just keep the heat sink electrically insulated from the chassis.

This project required me to refresh my memory on how to tap a 4-40 hole. I went back and watched the short video I made on the tribal knowledge that Pete had shared with me. Out came the Tap and Die gear and the machine oil. The process went very smoothly.

 Here is what I did to get the heatsink in place:

1) After removing the original heatsink, I gently bent the leads on the IRF510 so that the transistors outer edge would be flush with the edge of the PC board.
2) I put a strip of thick tape (Gorilla Tape) along the lower side of the heat sink. This will keep the heat sink from shorting to the chassis.
3) I placed the heatsink where I wanted it, and carefully marked where the mounting screw (through the transistor’s tab) should go.
4) Drill! Tap! (see video) https://www.youtube.com/watch?v=LuqliWT1k5A
5) I applied some heat sink compound (or Desitin!) and then attached the transistor to the heatsink.
6) I put a few drops of glue between the heatsink and the board and the chassis, just to mechanically stabilize it a bit.
7) Bob’s your uncle.

It seems to work great. The MOSFET stays cool. even after long “old buzzard” transmissions. And I notice no stability problems. It was fun to put to use some tribal knowledge and refresh a mechanical skill.

My Extroverted BITX40 — On (but not in) a Box

I was going to put the BITX40 Module in a box today, but I just couldn’t bring myself to do it. That board looks too good to be hidden inside a box. So I put it topside. That’s the analog VFO to the right. You can see a fan off to the left — that is perhaps temporarily in lieu of a large heat sink for the final. You can see the two Gel cells in the background. I am indeed running 24 volts to the final, and am putting out about 20 watts. I had three nice contacts today on 40: WB2RON up on Long Island said I was “20 over”. Later I worked W1SJ in N. Vermont — I was 5-9. Then — icing on the cake — DK1NO in Stuttgart. I was 5-8. TRGHS.

I kind of like this arrangement — it has the “three dimensional” feel of an old tube rig. This obviously wouldn’t be good for portable operations, but I am not planning on going portable. There is a lot of room under the chassis. I could put a digital VFO in there and put in a switch so that I can easily go from digital to analog.

Two Gel Cells and a Heat Sink — BITX40 Power Hack

I blame Pete for this. And Farhan. Pete has been leading us astray with all his talk of high power linear amplifiers (“Two 813s kid, that’s all you need!”). And Farhan practically pushed us beyond QRP limits by placing a separate DC power connector for the IRF510 final amplifier on his new BITX 40 Module board. Farhan writes:

There are jump-points from where you can add more modules like the DDS, more bands, better audio amplifier, etc. Imagination is your limit. You can separately increase the power amplifier’s supply voltage to 25 volts to be more than 20 watts of power : You will have to add a better heat sink. The mods are on the way! (from hfsigs.com)

 A while back Chris KD4PBJ sent me some very nice heat sinks — one of those would fit quite nicely on the PA side of the BITX40 board. And I just happen to have two 12V Gel cell batteries. One will power the board and the two together will power the IRF510. With 20 watts out to my dipole I feel confident that I will WIN the upcoming ARRL Phone Sweepstakes (in my category: Homebrew VFO, Northern Virginia).

SolderSmoke Podcast #191 RIGS! REAL RIGS!, BITX40 Module, EMRFD, MAILBAG


 SolderSmoke Podcast #191 is available:

http://soldersmoke.com/soldersmoke191.mp3

TRAVELOGUE AND FAMILY DOINGS: Pete son’s wedding, Billy’s Birthday, Gonzalo safely home in the Dominican Republic, MORE BEARS IN THE SHENANDOAH WOODS

BIG NEWS: EMRFD LIVES ON! Three cheers for Wes and for Tom Gallagher of the ARRL.

BENCH REPORTS:

PETE: FPM Rig. Some Halli history. A TRUE RIG! Working Japan.
WITH 600 WATT LINEAR AMPLIFIER!!!!!!!!!!!!!!!!!!!!!!
New FEELTECH Sig Gen.

BILL: Farhan’s BITX Module
Built to Mod, built to get you started in homebrew
Very impressive. BITX in miniature. But completely recognizable.
REMARKABLY stable.
Farhan personally checking each one.
Ladies collective doing toroids. DONATION money bought them some Diwali candies!
VFO Drift: Will NP0 SMD caps and lower current help enough?
My Analog VFO — BANDSWEEP

QRPppppppppppp with REX’s Hamfest Buddy. Thanks Rex and Bob Crane.

HB2HB with KW4KD

MAILBAG
Jan’s Netherland Mate Mighty Midget
Charlie’s Kiwi DSB
Steve, Donald Fagan, and Jean Shepherd
Rob VK5RC repairs Tek Tube ‘scopes
Colin M1BUU Si5351 superhet
Denis Klipa and NRL 3538
Jonathan M0JGH Wizard of Wimbledon Matchbox rig
JH8SST Simpleceiver
Peter Parker Vk3YE Reviews Book
Peter GW4ZUA Welsh LBS
Michael Rainey helping hobbyist in Germany with tuning forks.

Reverse Polarity Protection

When I opened the package from India and saw Farhan’s s beautiful board with all those little SMD parts, I immediately worried about frying those parts by accidentally reversing the polarity of the 12 volt DC input. Believe me, this can happen. It is especially likely during the early, enthusiastic testing and experimenting that takes place in the days after the arrival of a new rig. So, my friends: Save yourselves the agony of fried components! Don’t let your BITX 40 Module go up in smoke! Install a simple reverse polarity protection circuit BEFORE you start working with your new board.

Here is what I did: I just took a diode (a fairly hefty diode) and I soldered it in between the pins of that neat little circular power jack that Farhan sent with the module. Be sure to solder it in so that it does NOT conduct if you have connected the power correctly. The arrow should be pointing to positive terminal. Then put a fuse (3 amp or even a 2 amp) in the line from the connector to the power supply or battery. If you don’t have a holder you can try just soldering the fuse into the line.

With these two little parts, you can save yourself a lot of grief: If (WHEN!) you connect red to black and black to red, that diode will conduct like crazy and will blow the fuse. You’ll just have to replace the fuse (and not the module).

On the Air with the BITX 40 Module

This morning I built a mic/PTT for the BITX 40. I used the little electret element that Farhan sent with the rig. The element sits atop the plastic tube from a pen. For the push-to-talk I used a little push switch that locks down (on) until you push it again (which opens it). This is very convenient — you don’t wear your thumb muscles out on long “old buzzard” transmissions! I used some PVC pipe and some wooden dowel to make the thing a bit ergonomic. It is held together with Gorilla tape.

It works great! I put the rig on the air this morning and very quickly worked KD3TB up in Pennsylvania — Irwin was testing his K3. Then I worked KM4LWP — James was only a mile or so from me, running 3 watts from a KX3. Then Mario, K2ZGW called in. Everyone said the rig sounds great.

In the picture above you see the rig, the mic and (on the right) the VFO.

On the Air with the BITX 40 Module

This morning I built a mic/PTT for the BITX 40. I used the little electret element that Farhan sent with the rig. The element sits atop the plastic tube from a pen. For the push-to-talk I used a little push switch that locks down (on) until you push it again (which opens it). This is very convenient — you don’t wear your thumb muscles out on long “old buzzard” transmissions! I used some PVC pipe and some wooden dowel to make the thing a bit ergonomic. It is held together with Gorilla tape.

It works great! I put the rig on the air this morning and very quickly worked KD3TB up in Pennsylvania — Irwin was testing his K3. Then I worked KM4LWP — James was only a mile or so from me, running 3 watts from a KX3. Then Mario, K2ZGW called in. Everyone said the rig sounds great.

In the picture above you see the rig, the mic and (on the right) the VFO.

Hacking the Hackable BITX 40 Module: VFO is the Way to Go!

I am having a lot of fun with Farhan’s new BITX 40 Module. I think I’m doing exactly what Farhan intended people to do with this rig: work on it, modify it, improve it.

I’ve been working on frequency stability. I was, I admit, skeptical from the start about the stability of a thumb-sized, SMD, varactor-tuned VFO with a ferrite or iron powder toroidal coil. Don’t get me wrong — it worked. But it drifted. It seems to me that it would be asking too much to expect a VFO like this to be drift-free. (But I may be wrong — are there any SMD, varactor-tuned VFOs out there that DON’T drift?)

First I thought it might be the 9 uH metallic core toroid. So I replaced that with a 10uH choke — no ferrite or iron powder in there. That seemed to help a bit, but SSB QSOs would still quickly drift into Donald Duck chatter. Then I thought it might be the varactor diode. I let it warm up. A lot. Still, it drifted. Then I thought it might be the trimmer cap, so I took it off the board. No change. During this process I noticed that even slight pressure on the board caused the rig to shift frequency. I began to suspect that the drift was just structural — a consequence of the physical characteristics of the SMD parts and the board. To get VFOs stable I’ve had to build them big: 10 X 10pf NP0 caps to make one 100 pf cap, large air-core coils, and big sturdy variable caps. I’d isolate the frequency determining elements in a box separate from the powered components. This little VFO just looked too small to be stable.

So faced with drift, at first I asked myself, “What would Pete do?” I took an AD9850/Arduino combination off the shelf and plugged the output into the “DDS” jack Farhan had placed on the board. I removed the 10uH choke. Viola! With the DDS tuned to 4.7 – 5 MHz, the receiver worked great. I briefly tried to updated the Arduino code to take into account the 12 MHz IF (so I could get an accurate frequency readout), but ran into the old painful Arduino IDE problems: Now it is claiming there are library problems. Not wanting to suffer through another round of digi-agony, I left well-enough alone. I used the DDS with the old code for one day.

But of course, I was not satisfied. Attaching a DDS or PLL synthesizer to the BITX 40 Module just didn’t seem right. Heck, it was kind of like just hooking up my FeelTech Chinese sig gen to the DDS jack. Farhan’s rig is simple, beautiful and ANALOG. The parts are small, but you can see them. You can put your scope probe on the collector of Q7 and see what is going on. DDS or PLL. It is a REAL HARDWARE-DEFINED RIG. So I decided to build a VFO. Pete calls VFO’s “grief machines” but for me, the grief machines are those little Arduino beasts. To each his own.

When I build a VFO, I start with the variable capacitor and the reduction drive. I found a nice one (with reduction drive) in my junk box. I tunes from 40 pf to 56 pf. I decided to use the super-simple Hartley circuit presented by Wes Hayward W7ZOI in SSDRA (page 34, fig 7).

I went with a 4.4 uH air core coil (wound on a cardboard tube from a coat hanger). Consultation with on-line resonant frequency calculators showed that I’d need to put about 180 pf in parallel with the variable cap. For this, I used a bunch (maybe 10?) of small value NP0 caps in parallel. This really helps keep the VFO stable.

As I did with my HROish receiver, I put the coil and the caps in one box, with the MPF-102 and associated parts in an attached Altoids tin. Everything was glued and bolted down very solidly.

I only built the actual oscillator stage — I decided to use the buffer amps on Farhan’s board.

The oscillator started right up. I had to add and then take away some turns on the coil to get it to run in the desired range. Then I plugged it into the DDS jack — the receiver was working immediately.

I noticed, however, that it seemed a bit less sensitive than it had been with the AD9850 DDS. And when I grabbed the wire going into the DDS connector, audio output jumped dramatically. It took me a few minutes to figure that out: I think the output from my VFO was not adequately turning on the diodes in the diode ring. When I grabbed the wire, I was putting a lot of noise into the mixer port, probably turning the diodes more fully on (but also letting a lot of noise through).

Fixing this problem part was fun: Looking at the BITX 40 schematic, I saw that the two 1000pf feedback caps in the original oscillator were still in the circuit. I figured those caps would be sending a lot of my VFO energy to ground. So I fired up my hot air rework station and deftly removed C91, the 1000 pf cap that is connected to the base of Q9. Instantly the receiver started inhaling as it had with the DDS VFO. That was a very satisfying fix.

This whole VFO project was very satisfying. It was all done in one day, and all the parts came out of my junk box. I think I ended up with an LO frequency source that matches up in a pleasing way with the analog circuitry in Farhan’s rig. And here is bonus that I think is just what Farhan had in mind: this kind of circuit adds a definite homebrew element to the module rig.

I found that this external VFO improved stability significantly. I don’t know if it is as stable as the DDS, but with the external VFO the receiver no longer drifts away as I listen to SSB signals.

Farhan on What’s New in the BITX 40 Module

Writing to the BITX e-mail group, Farhan provides some very interesting information on the philosophy behind his new BITX 40 module, and on how it differs from earlier BITX designs:
The new builders are often caught in a catch-22 : to get on air they need to build a rig from scratch. but to build a rig, they need lots of experience. A way out was to provide working boards where we can get on air quickly, and then start improving and modding the circuit. this is the spirit behind the new boards. Consider them like you would consider a raspberry pi or an arduino : simple, working circuits around which you can grow your own radio.

In the new bitx boards, I have tried to keep as close to the original bitx as I could. however, there are a few departures that I thought the bitx builders here would like to know about.


i have to admit though, strangely, i am less familiar here with bitx than many others on this form. arv, leonard, dan, andy and others have build far many more version than I did. I just happen to be the first one to build a bitx. this as much an acknowledgement of their inputs. without all you folks, bitx would not have had the kind of traction that it now enjoys. I suspect that it is the most built transceiver in the world.

So, here are the changes from the original bitx.

1. SMD
The SMD components make for virtually error free boards assembly. We used the biggest sized SMD components. In fact, the resistors and capacitors are about the same size as a quarter watt resistor that is soldered standing up. They are very easy to desolder without messing around with the desoldering wick and solder pumps. All you do is to lay the soldering iron’s bit on the component such that the flat end touches both sides at once and after a few seconds just drag the component away. I soldered the sample boards with my regular, 2 dollar, 25 watts iron without using a magnifier (I wear reading glasses).

1. 40 Meters
It is just that with the sunspots fading away, 20 meters in the tropics is far less active than before. Many of the us South Indian hams hang out on the lower end of 40 meters every morning and evening. Hence, the choice. That doesn’t mean that i can’t be converted to 20m! There are several ways to change to 20 meters. Keeping the VFO same, change the crystals (and hence the IF) to 8.833 MHz and rework the band pass and the low pass filters. I will work out the details in a few weeks and post them here.

2. A new bandpass filter
The original bandpass filter was quite lossy. I didn’t know how to use any CAD tools when i sketched it. I was actually on a long haul flight when I designed that filter. The new filter configuration is very interesting one. I saw it on PA3AKE’s site. This is a triple tuned circuit with very good out of band attenuation while maintaining very low loss.
In the last then years, ecomm has made it possible for us to globally access good quality toroids anywhere in the world. Hence, we have used T30-6 toroids with excellent low loss. I measured it at just 2 db, the original had more than 6db loss.

3. VCO
The original oscillator on the BITX used a variable capacitor. These were noisy, and often of inferior quality. In any case, they are no longer available. Instead, we have used a varactor diode for tuning. The greater benefit of using a varactor to tune the oscillator is that the tuning control only carries a DC voltage. You can install it anywhere. If you need finer tuning control, you can add a second lower value tuning pot in series with the main tuning pot. It is easier to add FLL to a VCO.

4. Audio muting
The original BITX used just a switch to move from receive to transmit. The receive voltage charged receiver’s audio preamp’s decoupling capacitor and it took time to discharge. this kept the audio preamp active even on transmit and caused a very sharp audio noise on the transmit change over. Now, the other section of the T/R relay is used to cut the audio off to the LM386 as soon as transmit line is energized.

5. A better T/R system
The original bitx didn’t have a PTT. this one has two relays to switch the linear amplification chain in and out of the circuit, mute the audio and change over the antenna. These changes lead to a very stable linear amplifier and smoother change over.

6. Mic amplifier
The original mic amplifier easily saturated. The new design, thanks to dan tayloe, has a better head room and provides very clean modulation.

7. The fixed BFO
Though the PCB has the provision for a trimmer and an inductor to pull the crystal frequency. I discovered that with five matched crystals, if you used 4 in the ladder filter, the fifth’s frequency fell right into the perfect sweet spot for LSB work. You might need to add the trimmer and an inductor back for USB work.

8. DDS connector
To use the DDS, you will have to remove L4 (the VFO inductor) and inject the DDS/PLL output into the connector provided.

There are some smaller mods that people can try out:
* The current in the receive amplifiers can be reduced if you don’t have any radio hams in your neighbourhood who run kilowatt amps.
* The capacitor between pins 1 and 8 of the LM386 can be removed if you prefer headphones to speakers.

A Package from Hyderabad: Farhan’s BITX 40 Module Arrives in Virginia

I am having a really EXCELLENT radio morning here at SolderSmoke East coast HQ. I made some progress on the Armand HRO receiver — just squaring away some of the too-long leads and improving the shielding a bit. Then I was looking out the window as the mailman arrived. What was that little box he was leaving us? Wow! A box from Hyderabad! The BITX 40 module arrived, wrapped in a very interesting piece of Hyderabad newspaper. Very FB. Thanks Farhan. I will surely be writing and talking about this rig in the weeks to come.

UPDATE: I just realized that the BITX module fits very nicely into a TenTec TPC-45 cabinet that Armand gave me a while back. TRGHS.

Update on Farhan’s BITX 40 Module

It is truly a thing of beauty: http://www.hfsigs.com/

The boards come assembled (as seen above). You can then add peripherals and modify away. It is “hackable.”

Hackable

The BITX40 will inspire you to experiment. Modify it, mount it, tweak it, change it.
The PCB uses all analog large sized SMD components that are laid out on an easy to understand manner on a double sided board with broad tracks. This can be your main module around which you can start experimenting. There are jump-points from where you can add more modules like the DDS, more bands, better audio amplifier, etc. Imagination is your limit. You can separately increase the power amplifier’s supply voltage to 25 volts to be more than 20 watts of power : You will have to add a better heat sink. The mods are on the way!
The board can be installed inside any box that you like. Make your own station rigs, man-packs, trail radios or mount it in a cigar box and leave it on your bedside table. The tuning capacitor has been replaced by a varactor tuning so you can place the tuning knob anywhere as it only carries a DC voltage.

Farhan writes:

For the last few months we have been working bringing low cost, tested SSB boards. Finally they are here. Priced at Rs.2200 At the moment, they are available only in India until we sort out an inexpensive way to post them to other countries. Visit www.hfsigs.com and pick up one!

 The BITX40v3 is a complete 7 MHz SSB transceiver on a board that puts out 5 watts of clean audio and it has a very crisp, all analog receiver. It is based on the popular BITX circuit. It is a high quality double side, PTH PCBs with machine assembled SMD components, hand wound coils and each of them is individually tested. All the connectors and wires needed are included in the kit.

Update on Farhan’s BITX 40 Module

It is truly a thing of beauty: http://www.hfsigs.com/

The boards come assembled (as seen above). You can then add peripherals and modify away. It is “hackable.”

Hackable

The BITX40 will inspire you to experiment. Modify it, mount it, tweak it, change it.
The PCB uses all analog large sized SMD components that are laid out on an easy to understand manner on a double sided board with broad tracks. This can be your main module around which you can start experimenting. There are jump-points from where you can add more modules like the DDS, more bands, better audio amplifier, etc. Imagination is your limit. You can separately increase the power amplifier’s supply voltage to 25 volts to be more than 20 watts of power : You will have to add a better heat sink. The mods are on the way!
The board can be installed inside any box that you like. Make your own station rigs, man-packs, trail radios or mount it in a cigar box and leave it on your bedside table. The tuning capacitor has been replaced by a varactor tuning so you can place the tuning knob anywhere as it only carries a DC voltage.

Farhan writes:

For the last few months we have been working bringing low cost, tested SSB boards. Finally they are here. Priced at Rs.2200 At the moment, they are available only in India until we sort out an inexpensive way to post them to other countries. Visit www.hfsigs.com and pick up one!

 The BITX40v3 is a complete 7 MHz SSB transceiver on a board that puts out 5 watts of clean audio and it has a very crisp, all analog receiver. It is based on the popular BITX circuit. It is a high quality double side, PTH PCBs with machine assembled SMD components, hand wound coils and each of them is individually tested. All the connectors and wires needed are included in the kit.