❌

Normal view

There are new articles available, click to refresh the page.
Before yesterdayMain stream

Field Day with Farhan, his Family and an sBITX Near Hyderabad, India

25 June 2024 at 15:07

Farhan and his son Rayyan with an sBITX

The SolderSmoke crew thought it had a tough time this Field Day:Β  Pete N6QW had hoped to do something, but was stymied by hot California weather.Β  Dean KK4DAS had even worse weather.Β  Bill HI7/N2CQR was at a remote QTH with an HW-8 and a wire antenna -- he managed just ONE contact (W7RN in Nevada on 15 CW).Β  But none of us had as much trouble as our friend Farhan had.Β  Β InΒ  his account of Field Day in Hyderabad, we see an intrepid ham standing up against the slings and arrows of outrageous fortune that Field Day often throws at true radio amateurs.Β  Here is Farhan's Field Day story:Β 

-----------------------------

You asked for it, so here it goes...

I got the chance last evening to head out to our farmland. My daughter Ramsha had her friend were over. By the time we all got into the SUV, it was already 5:30 pm. I had loaded in the Spiderbeam fiberglass pole, the sbitx with LiPo battery and an EFHW ATU strapped on, into the back into my backpack,Β  the toolbox with a few hand tools.

On the way to the farm, rain begin to come down. Rayyan (son, VU3ECQ) started said as much, I turned up the volume on Bruno Mars...

By the time we got to the farm, the rain was over(Ha!). We immediately begin to set up the antenna. I chose an inverted V config for the antenna and to use a tree as the support. The spiderbeam, as any who has been taken in by it knows, is a telescoping 33 feet high mast made of fiberglass. A curious villager decided to help us too. The girls had already taken off to pick the Mulberries.

So, Rayyan, the curious fellow, and I tried to telescope out the mast. The curious fellow, having never read the manual, picked up the mast from the wrong end and all the pieces fall out the other end. (Censored @#$%...). Within 15 minutes, we had all the pieces put back in the order of their thicknesses. I scotchtaped the center of the 66 feet wire to tip of the mast and we all hauled it up vertical. For those who don't forget maths, you can figure that two section of 66 feet wire will be exactly 33 feet high and when you tie this to the high end of a 33 feet high pole -- they just hang down vertically in a straight line. I was trying hard to remember the math teacher's name when the telescoping mast decided to untelescope into a 5 feet, collapsed height. My son commented that it has worked as advertised. Now, I wanted to remember my son's Moral Lessons teacher's name...

Next, we scotch taped the center of the 66 feet wire to approximately 2/3rd height. The curious guy and I walked it up back and took it to the tree. Rather we tried to. The branches kept getting in the way. Finally, managed to get within 4 feet of the trunk and I declared that we could just tie it up with the packing nylon rope bundle we were carrying. We did and it held up.Β 

By now, the two ends of wire had gotten all twisted around each other. We all had an excellent arm workout trying unwind them. The techniques -- never mentioned in any antenna handbook -- is to hold both ends of the twisted pair in one hand each, spread out your arms and make overhead sweeping motion to flick one wire over the other. This method only adds more twists into the wire. I discovered that wires could be twisted around each other both ways. There is no untwisting them. I discovered this amazing feature!

After watching us for 10 minutes, Humera, my XYL, asked us to forgive the world and bring down the mast and untangle the wires on the ground. By now, a stray cow had also sauntered in on her way back home. I think our language attracted her. She was bellowing for her calf to come and watch.

Next, we, efficiently undid the wire twists. Rayyan and the curious fellow held the two ends away from each other and I raised the mast. Or rather I tried to. At 45 degree tilt, the mast sections add up huge amount of weight. I was tottering around with it when it thankfullyΒ  leaned onto the tree branches. At this time, I declared it done. We tied the mast at 6 feet height by the rope to the tree trunk. One end went to the a branch of a bush and the other we walked to the point where it was taunt and touched the ground.Β 

I brought out the radio, much to the curious fellow's surprised, who was looking forward to me doing more entertaining things with the mast rather than a radio. We switched it on, I quickly peaked the ATU to maximum noise and keyed up. The sbitx shut off. Our battery was discharged.

An intrepid ham is never dissuaded by the flings and arrows of time which, when taken at a tide, leads to Field Day. I decided to move the operations to the farm cottage where we had power. But there was no supporting tree nearby. I decided to use the SUV as support.

We packed the SUV at an approximately correct distance from the vernadah of the cottage. We carried the mast over to the SUV and strapped it at two points: on the foot rest and on the overhead luggage rock. At this point the Spiderbeam fiberglass collaspible mast took a commercial break and demonstrated rapid collapse, into the much vaunted 5 feet size. Rayyan was rolling in the grass with mirth. This divided my anger between two opposing directions: towardΒ  my progeny and toward my antenna mast. I didn't move.

I thought like an engineer.Β  The curious fellow and I carried the mast to an illuminated part of the farm, laid it down, and scotch taped each section to the next as the spiderbeam folks had warned us to do. It is strange how memory works better when your blood pressure is up.Β 

The mast went up again, this time strapped to the SUV's rack, door column, and the footrest. I setup the radio on a table outside the cottage, running the extension cord from inside. The SUV and the antenna were too far for the EFHWΒ  to reach the radio.Β 

We asked Humera (XYL) and the girls who were watching us while having their mulberries to DO SOMETHING and not just SIT THERE. So, Humera got inside the SUV and started to roll it towards the cottage. A loud crunching sound announced the sad departure of the sunflower plants we had tied the other end of EFHW fromΒ  mother Earth. The EFHW had unrooted its support as the SUV pulled it away. These minor inconviences never deter a determine man, remember Gandhiji!Β 

Finally everything was in place, and we fixed up the rig but the microphone wouldn't key up. So what? I can just operate from the in-built mic and the thoughfully provided on-screen keyboard for CW, right? Well I could but I needed to key CW contiuously to set the SWR. So I opened up the mic. The curious fellow who had carried the radio to the new operating position was new to radio etiquette. He had just picked up the radio and walked, dragging the mic through the slush and weeds. The mic connector had come out.

I took the matters into my hands, by now, Rayyan was trying to show empathy for the old man by making loud noise like Aww! Shucks! and other unmentionables. I cut the cable with teeth, unbraided a small section and wired it up on the connector so I could short it to key the rig. Why can't the imbecile radio designers think of providing a tune button on the screen??

Finally, everything was in place. I tuned up and AIR net was on. This is the national evening SSB net on 7150. I tried breaking in with SSB a few times but didn't get through. Finally, I changed to CW and called. The net control asked "the CW station to QSY, this is the AIR net....". Finally some other SSB station who could copy my CW translated my CW to the net control and we had a three way contact.

At this point the girls declared we had to head home now that I had had my contact.

I was about to let out my public school vocabulary when I heard them say that they were hungry and there was lamb curry at home. The idea of getting back home and drying out, and eating the hot lamb curry and mangoes was too much for me. We folded up. But the mast refused to collapse. The curious fellow who had taken charge of the mast engineering had finally gotten hang of it. With superhuman strength, he had pulled the section of the mast out so tightly that no power on earth could potentially loosen them. I decided to trick the mast into thinking that we wanted it to stay up, so we put it back up vertically and slammed it into the ground. It dutifully woke up and demonstrated the much vaunted ability to fit back into a 5 feet tube.

I looked into the darkness to find the EFHW winder but I couldn't locate it. The curious fellow had left, scared by the racket the radio was making. The cow and the calf had gone home. We too headed back home.Β 

In the picture, you can see Rayyan standing while I am checking into AIR net. In the background is the SUV with spiderbeam fiber mast that is easy to carry in a 5 feet size.

73, de Farhan VU2ESE with a little help from my friends and family.

Farhan Talks Radio Tech at SolderSmoke HQ (EAST) (TWO VIDEOS!)

1 June 2024 at 11:48

Great stuff!Β  We were really fortunate to have Farhan and Humera visit the SolderSmoke East shack after Dayton and FDIM.Β  Dean and I had a chance to talk BITX with the creator. Here is the two part video.Β  Most of the tech talk is in Part II (below).Β Β 

Β 

Farhan and his zBITX

Dean and Farhan with three sBITXs

Dean's homebrew sBITX

Farhan Phone


Old Tricks, Lore, and Art -- Freezing and Baking our LC VFOs -- An Example from Cuba

29 April 2024 at 10:40


Pavel CO7WT explained why Cuban hams used a process of thermal endurance to improved the frequency stability of their homebrew rigs:Β 

Β  --------------------

I'm CO7WT from Cuba, I started my endeavor in ham radio with a islander board.

They (FRC, like ARRL but in Cuba) made a print of a PCB to build the Islander, with component numbers and values, making construction fool proof, I think it was on the 90 or end of the 80...

Mine was built with scraps from an old KRIM 218 Russian B&W TV as Coro's explain, later on I get the 6bz6 and 6be6 tubes for the receiver (this worked better than the Russian parts) the VFO was transistorized, made with Russian components. AΒ friend CO7CO Amaury, explain me a trick: thermal endurance:

For a week put a crust of ice on the VFO board by placing it in a frosty fridge during the night. Put them in the sun by day.Β This indeed improved stability, this was an old trick.

By thermal endurance I mean improving thermal resistance vs tolerance, meaning that tolerance doesn't vary as much with temperature changes.

Β It's crazy, but it worked!!

I remember that my vfo was on 7 MHz, with Russian kt315 as normal Russian transistors and capacitors, nothing 1-5%, 20% at most, it ran several khz in 5-10 min, mounted on a Russian "Formica" board (no PCB) and wired underneath.

After that treatment to the complete board with components and everything, including the variable capacitor; I managed to get it to "only" noticeably in the ear after 30-40 minutes.

To me it was magic!!

Basically, what I'm describing is just "thermal annealing", but Cuban-style and with more extreme limits.

In a refrigerator you could easily reach -10 c and in the sun for a day in Cuba 60-80 celsius at least.

In Cuba in the 1990s-2010s many designs of DSB radios proliferated, both direct conversion and super heterodine (using an intermediate frequency)

At first tubes and then transistors, mostly using salvaged parts, so it was common to find 465/500 kHz (if common Russian) 455 khz and 10.7 Mhz with or without "wide" filters since narrow filters for SSBs were not scarce: they were almost impossible to get.

Not only that, crystals, ifs, PCBs, transistors, etc.

Then, around the 2000s, Russian 500 khz USB filters began to appear (from Polosa, Karat, etc. equipment from companies that deregistered and switched to amateur radio) and that contributed to improving... Even though at 7 MHz 500kc if is very close.

I made many modifications with the years mostly from 1998 to 2004 ish... better filters in front of the first RX stage (same IF described between stages) improved selectivity and out of band rejection, remember we had on that days broadcast as low as 7100 khz

Tx part was a pair of russian 6P7 (eq. RCA 807) in paralell, etc.

The JagΓΌey and others is one of those evolutions...

Β This is something I remember...

73 CO7WT

----------------

This is not as crazy as it sounds.Β  We can find versions of the same technique in the writings ofΒ Roy Lewellan W7EL, Doug DeMaw W1FB, and Wes Hayward W7ZOI. Β I found this 2007 message from our friend Farhan VU2ESE:Β 

I think the word 'annealing' is a bit of a misnomer. the idea is to thermally expand and contract the wiring a few times to relieve any mechanical stresses in the coil. after an extreme swing of tempuratures, the winding will be more settled.
this techniques owes itself to w7EL. I first read about it in his article on the 'Optimized transceiver' pulished in 1992 or so.
but all said and done, it is part of the lore. it needs a rigorous proof.
- farhan

https://groups.io/g/BITX20/topic/copper_wire_annealing/4101565?p=,,,20,0,0,0::recentpostdate/sticky,,,20,1,860,4101565,previd%3D1193595376000000000,nextid%3D1194269624000000000&previd=1193595376000000000&nextid=1194269624000000000


And here is another example of coil boiling:Β 

https://www.qsl.net/kd7rem/vfo.htm

-----------

I can almost hear it,Β  all the way from across the continent:Β  Pete N6QW should, please, stop chuckling.Β  Obviously these stabilization techniques are not necessary with his beloved Si5351.Β  Some will see all this as evidence of the barbarity and backwardness of LC VFOs.Β  But I see it as another example of lore, of art in the science of radio. (Even the FCC regs talk about "Advancing the radio art." ) This is sort of like the rules we follow for LC VFO stability:Β  keep the frequency low, use NP0 or silver mica caps, use air core inductors, keep lead length short, and pay attention to mechanical stability.Β  Sure, you don't have to do any of this with an Si5351.Β  Then again, you don't have to do any of this to achieve stability in an Iphone. But there is NO SOUL in an Iphone, nor in an Si5351.Β  Give me a Harley, a Colpitts, or a Pierce any day.Β  But as I try to remember, this is a hobby.Β  Some people like digital VFOs.Β  "To each, his own."Β 


Thanks Pavel.Β 


A Contact with my Old Azorean DSB Transceiver

5 March 2024 at 10:36

I've been thinking about balanced modulators, and I wanted to see how some of my early circuits performed.Β  So I pulled this OLD Double Sideband rig off the shelf and fired it up. The balanced modulator -- and everything else! - worked fine,Β  and I soon made contact on 17 meter SSB with Gene, AB9GK.Β 

This was the first DSB transceiver that I ever built.Β  I made this out in the Azores, probably in 2000 or 2001.Β  Years later I had replaced the RF power amplifier with a "JBOT" (Just a Bunch of Transistors) designed by Farhan.Β Β 

Over on my YouTube channel a comment came in from my friend Jack:Β Β 

"Looking inside and seeing the o-scope probe in place while the radio was on the air reminded me of neurosurgery where the patient is awake and talking while the surgeon probes different brain regions soliciting feedback. Sure, ham radio isn't neurosurgery, but it's not too far at times. Also, you already have rocket science covered."


Here is an article about my build of that first rig:


I think the article captures well the trials and tribulations faced by new homebrewers, perhaps with the twist that comes from being out in the middle of the Atlantic ocean.Β Β 

Mike WU2D is having similar fun with his homebrew 10 meter DSB transceiver:Β 

I was struck by how similar Mike's early QSO experiences were with mine.Β  We both put our DSB transmitters on the air before they made their way into real cabinets or boxes.Β 

Here's mine from 2001 in the Azores:Β 


Innovation and a Dual Band Sweep with Version 2 of the 15-10 Transceiver

25 February 2024 at 17:29

Here are a couple of videos on Version 2 of my 15-10 SSB transceiver.Β  In the video above I try to show the advances and innovations that have been made since the start of my BITX construction adventure back in 2013.Β Β 

Β The video below shows the receiver in action this morning on 15 and 10 meter SSB.Β  I think it sounds pretty good.Β 


Click on the image for a better look

Farhan asked what the passband of the 25 MHz crystal filter looked like.Β  I sent him this.Β  I think it looks very good, and shows that it is possibleΒ to use an IF this high.Β  This permits us to not only set up the transceiver for dual band coverage (in this case 15 and 10 meters), but it also allows for a lower frequency VFO (in this case around 3.5 MHz) with a resulting increase in VFO stability.Β Β 


❌
❌