Re: BITX QSO Night - Need Alternate Frequencies
I haven't operated my bitx40 on 7277 for several Sunday evenings now because of the strong SW broadcast station on 7275. I don't have a notch filter to get rid of the 2KHz tone screaming out of my speaker. I have used my KX3 (with notch filter) to monitor 7277 at times, but notching a piece of audio at 2KHz does degrade intelligibility. So I haven't had much fun lately with my bitx40, back to using my KX3. Next Sunday if 7277 is unusable, I will try 7285 if it is clear and see how that goes (there is usually a net that occupies it until 7pm or so ET). Last Sunday I took a listen on 7282, but a broadcast station came up on 7280 and caused the same problem as with 7277.? 73 - AL
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On Mon, Oct 9, 2017 at 01:07 pm, Al Duncan VE3RRD wrote:
I checked 7285 several times Sunday night and it was mostly clear. That is a QRP frequency often used by SOTA and other groups. 73, AL
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Hi Joe
Did you make any mods to get 11 watts at 13.5v? I only get about 6 on cw.
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Same scenario to Canada. Shipping and tracking where first rate, but DHL charged 26.00 CAD import fees. Would have been free by post.
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Attn Farhan, for the website: Delivery by India Post - check. By DHL - check, *except UK*. They're gouging the gullible 21 quid a time - half the item price!
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As a footnote, my BitX40 plus Raduino arrived today by DHL.? The tracking was first class once I had the number.
On the downside, I had to pay an extra ?21 in taxes before they would release for delivery.? This seems a lot on top of goods costing only around ?45.
The kit is well packed and looks in good order.
I've printed?VE1LEB's 'Ergonomic' case and look forward to meeting some of you on the air soon.
Vy 73,
Dave, G8XUL
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sarma-ji,
There is very little 'original' in any open source project. Like most 'benevolent dictators' of any open source project, my principal job is to assimilate changes suggested by people and dissimate them. i try to keep changes to a very minimum. I don't fix what is not broken, I don't introduce new features that break the old circuit.
For instance, the mic amplifier of the original design was faulty, changing the bias resistors has improved that. Similarly the receive pop is removed with the introduction of an unused section of a DPDT relay to cut the audio on tx. However, there are other interesting fixes like keeping the audio amp alive on tx for sidetone that need change in the PCB. I refrain from doing those so as to maintain 'backward compatibility' with those who are working with the older PCBs.?
Your suggestion for using the BAT54S diodes was very timely. It sorted out the balance issues with the front-end mixer as well. I used them now everywhere. Unfortunately, they don't work too well at VHF, I continue using 1N4148 or 1N5711 for anything higher than 100 MHz.
Allard's modifications are a case in point, he has really taken the functionality of the Raduino and BITX40 to completely different level with his software and hardware hacks. However, I continue to keep the original software in the shipped boards as it is simple upgrade for those who want to dabble with the code or rewire some parts of the board.?
- f
On 10 Oct 2017 10:09 am, "Mvs Sarma" < mvssarma@...> wrote: It is nice on your part to keep the analog vfo section populated for aspiring? users, skipping only those parts that are interfering with si5351.
I did nothing Farhan jee, but a nano suggestion after seeing the datasheet that these series diode pair works for frequency mixer. You are an eminent designer of world repute and and my coso called contribution for a smd part is infinitismal.
?All the best and we the enthusisasts look forward for more of designes from you.
?Simply- you struggle to design and we enjoy using the,
?All the best again
?regards
?sarma
vu3zmv
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Re: LED Backlight ... It's 2 LEDs in series, the series resistor is marked 111, which I presume to be 110 ohms. Given the typical LED drops 1.3V when conducting, and supply is 5V,? I = E / R = (5-2.6) / 110 = 2.4/110 = 21.8mA. Do you really think this contributes much to the heating of the 7805?
OK, cut the track, but put in a pot (1K?) and you've got control of the light output - handy for night-ops. :)
73... Dex, ZL2DEX
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It is nice on your part to keep the analog vfo section populated for aspiring? users, skipping only those parts that are interfering with si5351.
I did nothing Farhan jee, but a nano suggestion after seeing the datasheet that these series diode pair works for frequency mixer. You are an eminent designer of world repute and and my coso called contribution for a smd part is infinitismal.
?All the best and we the enthusisasts look forward for more of designes from you.
?Simply- you struggle to design and we enjoy using the,
?All the best again
?regards
?sarma
vu3zmv
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a number of new builders are mystified about the parts missing around the modulator and the bfo. here is the story :
when the bitx40 first started shipping, we had an analog vfo tuner with a varactor. this proved to be drifty. we soon introduced the raduino board - an arduino controlled si5351 board for general purpose rig control. this feeds into the vfo circuitry. we kept the original pcb design so that our past and future builders dont have different boards, we just skip some parts to prevent the vfo from oscillating and inject the si5351 signal into the vfo's base. there are still purists out there who insist on using the analog vfo. they can add those caps on their own.
the balanced modulator/demodulator originally used a pair of 1n4148 diodes balanced with a 100 ohms preset. this too proved a tough thing to set for those who didnt have a scope. we changed that, thanks to mvs sarma's recommendation, to bat54s diode pair l. the bat54s is a matched pair in smd format that doesnt need balancing. this is why you see a number of components missing around the det/modulator.
have fun, poke around and see if anything else needs explanations.
73, f.
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Werner WB6RAW wrote... SUNKEE LM2577 DC-DC Adjustable Step-up Power Converter Module I haven't had time to take it out of the packaging yet, but I ordered this one from eBay. It is rated t 6A (9A max) so it's a bit of over-kill, but I'll give it a try. It didn't take much more than two weeks to arrive. -- 73 Keith VE7GDH
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Thanks Jerry
I may just use the radio at 5 watts for now, and may put a 7812 on the main board power for insurance. As long as the supply is far enough above 12v to allow the regulator to work, it should relieve some of the stress. My one supply runs as high as 14v, so that probably stresses r141 an q13 quite a bit.
I'm making lots of qsos on 5 watts and have several other radios if I want to go qro.
73
Brent
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Hi,
?I have 3 bitx40 v3 , all running 13.5v.? The have been running perfectly ok... for nearly 24 hours a day... for weeks at a time.
I use the same voltage for both rig and PA - output around 11 watts. I did try 19v at the PA , but only got around 5-6 watts more... Not enough for me to keep it at that level.. However, I do have a large computer cpu heatsink and a low noise (can barely hear it)? fan for the PA.
I run hours of straight none stop digital modes and at the 13.5v for rig and PA... It is cool, hardly detectable it is on even on
Joe VE1BWV
On Mon, Oct 9, 2017 at 9:53 PM, Brent Seres <brentseres1@...> wrote: Jerry had some comments and concerns with several of the stock bitx components being stressed at voltages over 12 volts. I'm currently using a supply running about 13.5 volts. Has anyone had any problems with things failing when using a similar supply or fully charged lead acid batteries? I know the PA is fine, just wondering about the rest of the board.
Thanks
Brent
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Raj has seen several boards with R141 blown: ?/g/BITX20/message/32096
That resistor and the mmbt3904 at Q13 have quiescent currents that exceed their dissipation ratings.?
Q13 is connected to the antenna, can also blow if a nearby QRO transmitter causes Q13's Vbe to get excessive.
Transmit LPF caps will see around 100v pk-to-pk of RF (centered on ground) when driving 20 watts into 50 ohms,
at high SWR they will see considerably worse.
?
But many in the forum are successfully running with 24v into the IRF510.
I suspect most reports of damage are due to heat in the IRF510.?
That's how you learn. ?Good thing the IRF510's are so cheap.
Jerry
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On Mon, Oct 9, 2017 at 05:53 pm, Brent Seres wrote:
Jerry had some comments and concerns with several of the stock bitx components being stressed at voltages over 12 volts. I'm currently using a supply running about 13.5 volts. Has anyone had any problems with things failing when using a similar supply or fully charged lead acid batteries? I know the PA is fine, just wondering about the rest of the board.
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Jerry had some comments and concerns with several of the stock bitx components being stressed at voltages over 12 volts. I'm currently using a supply running about 13.5 volts. Has anyone had any problems with things failing when using a similar supply or fully charged lead acid batteries? I know the PA is fine, just wondering about the rest of the board.
Thanks
Brent
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John,
How much power do you get out of the rig, now, on 40M with 20V in the TX PA? I just ordered a DC Boost Converter from Amazon, too. I ordered this one:
SUNKEE LM2577 DC-DC Adjustable Step-up Power Converter Module
Is that the one you got? Seems to be good for 2amps output.
Thanks,
Werner WB6RAW
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On Oct 9, 2017, at 3:05 PM, John Beasley < john@...> wrote:
I installed a RF choke and decoupling capacitors on the input and output of mine and it helped quite a bit. I also use a DC Boost Converter from Amazon. ? ? ? I've got a cheapie $10 buck regulator off Amazon that generates some serious noise to my BitX, and I tried 2 different brands of mini DVM's (as a simple battery indicator) and both kicked off even more noise, but I also have an even cheaper boost converter built into the case to get my finals up to 20V that is nearly silent - Only a slight quiet hiss can be heard.? It seems to be rather hit or miss.
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I like the idea of controlling an amp in the IF section.? Boost the gain for the weak signal, reduce it for strong ones.
On Sat, Oct 7, 2017 at 4:35 PM, Dexter N Muir <dexy@...> wrote: You're welcome, Brent.
My anti-chunk (eventually) was an adaptation of I7SWX's. All-transistor. FETs are not essential for that - might be for AGC, but haven't got to that yet. Might even be able to use the clamp for both! I put a k or 2 (6.8 actually, just what was to hand and small enough) between clamp and amp - evidently reduces low-level hiss. I also put a delay on PTT release - just a few milliseconds, but cuts the Tx->Rx chunk.
73
Dex, ZL2DEX
-- Paul Mateer, AA9GG
Elan Engineering Corp.
NAQCC 3123, SKCC 4628
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yes...it DOES get hot.? put a small heatsink on it.? One of the issues is that it is the backlite for the LCD is connected to it. You can try changing out the series resistor for the backlite on the LCD to dim it down thus reducing the load or cut the trace and run dedicated power to it.
On Sun, Oct 8, 2017 at 11:59 AM, Ben Bangerter, K0IKR via Groups.Io <bwbangerter@...> wrote: The 5 V regulator on my raduino runs cool.? My raduino, including the LCD display, draws 76 mA at supply voltages from 8-12 volts.? Where is all your current going?? I removed the regulator and reinstalled it on the side of the board where the connctors attach.
Ben - K0IKR
-- Paul Mateer, AA9GG
Elan Engineering Corp.
NAQCC 3123, SKCC 4628
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Re: BITX QSO Night - Need Alternate Frequencies
As we all know there is on perfect frequency. I too have experienced QRM, SW broadcast and other difficulties on 7.277 but in general it is as good and probably better than what I have found tuning around.I have not found SW broadcast QRM to last very long at my QTH but of course your propagation is not the same as mine ? When I find 7.277 unusable I switch to BitX international at 7.177 but have found little action there. When I was beaming Europe I chose 7.177 and worked a few stations. It is good to remember that many countries do not permit operation above 7.2Mhz If trying to work DX I will use 7.177 +/-
7.277 was becoming known as a BitX net frequency and that will become better known with time. I have found BitXers on 7.277 during the week.,and usually start there on week days.
As with most nets, if the frequency is occupied or otherwise unusable the +/- rule works to find the nearest clear freq. but of course QRP power levels make this approach somewhat more difficult. I like the idea of a "go to" freq. like 7.285? but if 285 is busy I would go to 7.177 or resort to +/- Few antennas work well with a large frequency excursion and I will re-tune my matching network to achieve the best radiated power from our little radios if I have to move very far.?
Posting a usable Frequency to the group seems to work as does QRPspots and DXSummit postings, almost real time but we need to remember to check the internet.
Hope to work your BitX, Willy? ?W1LY
On Mon, Oct 9, 2017 at 5:18 PM, MAc B <sp9mrn@...> wrote: Something below 7200 pls ;-)
?
MAc
sp9mrn
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Hi Brent,
Yes, I posted about this a few moons ago, I modified my Bitx-40 by lifting one end of R127 and inserted a delay, see image.
73 Alf vk2yac
Brent Seres wrote:
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I wish....however I did manage about 3000km into northern Brazil the other night.
I hear myself in the headphones even when the volume pot is all the way down, effectively grounding the input to the lm386, so here is what I think must be happenning:
When I go to tx, the audio path to the lm386 is broken by k2, at points m1 and m2. Additionally, the Vcc to the lm386 and audio preamp is shut off by k1.
However, c110 and c114 continue to power the 386 and the preamp for a second or two. Audio from the mike amplifier enters the receive audio preamp through c116. Even though the audio path is disconnected, the active preamp modulates the voltage provided by c110 and c114 until they die, effectively providing a small audio signal at the lm386 output. Let me know if you think this makes sense.
Thanks
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Re: Use of BitX40 for WSJT-X
hmm...seems that a DPDT switch as a means to toggle the band and rout the output thru the LPF can make this a Bitx 4020 type system?
--
AncelB, MIT EE6002
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Brent Seres/ VE3CUS
AA9GG
Willy
Ancel