Re: using the BITX on RTTY
Hans, would it be possible to pull the crystals in a filter using the LED or Zenor Varicap diodes??
-Justin N2TOH?
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CAT question, audio connection for digital, residual signal observed on waterfall of Icom 7300
#ubitx
#ubitx-help
#ft8
I setup for the FT-817 38400 baud and do have transmit control. Am I supposed to have more (frequency control, etc) with fldigi & wsjtx or just transmit/PTT control??
I see a conflict on two schematics for the PTT and MIKE connections on the jack. Does the orange PTT go to the tip or sleeve??
It also goes into transmit when I turn up the audio gain on the external usb sound card. I can hear the modulation signal in the headphones but all I have is a rough signal at the dial frequency visible on my Icom receiver, with the RF gain turned way down.
Work with the o'scope is next.? ?It does appear to work fine on CW with a paddle, so the thought of a QSO excites me. :)
Ideas appreciated.
Bo W4GHV
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Re: BITX QSO Afternoon/Evening, Sunday, May 13, 3PM & 7PM Local Time, 7277 kHz in North America, 7177 kHz elsewhere.
I'm on with Tom, VE3THR with pretty good signals! Anyone else on?
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John - WA2FZW
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How to change the default power-on 7.150 MHz frequency on ?BITX
I wanted?my???BITX?to power-on on our club meeting frequency, instead of having to navigate to it?every time. ?Couldn't find any documentation on how to
set the default frequency?which is (was) 7.150 MHz. ?
Found this trick by accident, it might be documented, but just in case, here it is.
- turn on the radio;
- set the desired frequency on VFO A;
- set menu option: VFO B;
- turn off the radio whilst on VFO B?et voil¨¤.
You can also set the default VFO B frequency by selecting the VFO B frequency and turning off the radio on VFO A.
Yves vk2auj
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www.mwrs.org.au
Just had to build one of these www.hfsignals.com/index.php/ubitx/.. I used to have a KX3, but what I really wanted was a lunch box radio I could just leave on the ground outside.
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Re: Are the uBITX receivers ripe for improvement? -- And some other miscellaneous thoughts.
After listening to mine today on FT8 ?I'd say the RCVR I'd just fine. Or mighty fine!
It's been a joy listening to CW, SSB, & FT8 ?today.
I have problems on the transmit for another post.
Definitely interesting for projects with the pi and ubitx.
Bo W4GHV?
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Re: Are the uBITX receivers ripe for improvement? -- And some other miscellaneous thoughts.
These are all interesting comments. Especially on the tradeoffs of trying to preserve the simple battery operated radio concept or trying to use the uBITX as a component in a larger system. Yes, real coils, capacitors and crystals can produce functions in micro watts that brute force real time math requires multi watts to accomplish.
The comments on other peoples' comparisons with other receivers and the tradeoffs on sensitivity and overload are interesting.?
It sounds like the uBITX is a solid radio to use and modify for going in many different directions.?
Tom, wb6b
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Re: Variable uBitx IF bandwidth question
? ? Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ ? Owner - Operator Big Signal Ranch ¨C K9ZC Staunton, Illinois ? Owner ¨C Operator Villa Grand Piton ¨C J68HZ Soufriere, St. Lucia W.I. Rent it: Like us on Facebook! ? Moderator ¨C North American QRO Group at Groups.IO. ? email:? bill@... ? ?
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From: [email protected] [mailto:[email protected]] On Behalf Of Gary Hanson
Sent: Sunday, May 13, 2018 2:13 PM
To: [email protected]
Subject: [BITX20] Variable uBitx IF bandwidth question? I apologize if this topic was covered in an early message string, but I have only been actively reading the list for a couple of weeks and noticed a couple of posts about it. ? In the mid-1990s, I built the MXM transceiver kit and it used a 100 ufd or 150 ufd panel-mounted air variable capacitor to vary the IF band width of a four crystal Cohn filter where all the caps were the same value. If I remember correctly (at my age that isn¡¯t always a safe assumption), the IF band width would vary from about 100 hertz to 500 hertz, maybe as much as 1 kHz.? Sorry, but I am out of town and can¡¯t check the schematic. ? Based on some of my early QRP kit building experience, the change in capacitance you could get from varying the voltage was fairly limited.? Wasn¡¯t ?the shift around 25-50ufd??Also, the change wasn¡¯t linear across the entire range, though you could restrict the voltage and keep in a linear range. ? My question is this:? Are there varactor diodes today with enough capacitance range to shift from a 2 khz bandwidth SSB signal to a 500 Hz CW signal? ? I have not done the math to calculate how much capacitance shift would be required and in what range (...and not sure I even remember where to start - - so little time, so many dead brain cells). ?I assume it would need to go from the current 100ufd caps upward by at least another 200ufd ?I think my White Mountain 20 meter SSB transceiver from the 1990¡¯s used around 330ufd in the 8 MHz SSB filter. ? Also wonder if we could use a polyvaricap instead of diodes? ? I agree with Bill that this would be a pretty easy solution if the right varactor diodes could be found. ? Gary, KJ5VW
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Re: Buyer beware! RD16HHF1
Much of it is already captured on UBITX.net ? ? ? Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ ? Owner - Operator Big Signal Ranch ¨C K9ZC Staunton, Illinois ? Owner ¨C Operator Villa Grand Piton ¨C J68HZ Soufriere, St. Lucia W.I. Rent it: Like us on Facebook! ? Moderator ¨C North American QRO Group at Groups.IO. ? email:? bill@... ? ?
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From: [email protected] [mailto:[email protected]] On Behalf Of Gordon Gibby
Sent: Sunday, May 13, 2018 11:54 AM
To: [email protected]
Subject: Re: [BITX20] Buyer beware! RD16HHF1? ?I don't know if y'all have already done that....but writing up a little "white paper"" and putting it on the web site about little bite-size improvement steps like going to the RD16HHF1 for example, would make very helpful little bite-sized projects.? ? Again, you may have already done all that. ? I'm submitting gerber files right now to get my cheap homebrew soundcard-interface done as prototype batch?--- it is very similar to the EasyDigi but includes gain potentiometer trimmers and a RELAY for the push to talk, LED ptt indicator.? ??If it works....it will be freely available.? ?The previous (expensive-PCB-company-version) went through about 40 [expensive]??copies locally and elsewhere and many are 24/7/365 in service).? ? You guys have taught me a lot!!!! gordon ? ?
Also, keep in mind that if you plan to move from the IRF510 to the RD16HHF1,?
the uBitx final should have some adjustments to the transformer ratios and such.
The RD16HHF1 is not quite a drop in replacement.
Jerry
On Sun, May 13, 2018 at 09:17 am, Jerry Gaffke wrote: Allison has quite a few posts here.
None have discouraged experimentation with the IRF510's.
Quite the contrary.
She did however suggest you get your RF parts from reliable vendors,
be they IRF510's or RD16HHF1's.
Jerry . . . ?
On Sun, May 13, 2018 at 08:54 am, Russ Hines wrote:
Gents and ladies, I don't post much as I'm a busy broadcast engineer.? But I try to read often.
Allison's post contains wisdom.
Education tends to be expensive.? If your goal is IRF R&D, then knock yourselves out.? You will go through a lot of parts, and likely as not, spend a lot more time and money in acquiring the knowledge and experience.? In the end, you'll know what a part can or cannot do.? If that's YOUR goal, great.
For myself, my time is worth something to me.? I think it's false economy of both my time and money to blow up a few dozen $0.50 parts, chasing issues created by the selection of an inferior part from an unreliable source, when one appropriately selected and sourced $4.75 part will accomplish MY goal - to use a piece of equipment that I built.? The former is not worth the hassle.
If you need a cliche, here's two:? I'd like to "not reinvent the wheel," but would much rather "stand on the shoulders of giants."
Two cents duly submitted.
73,
Russ Hines
WB8ZCC
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Reply to: russ@.
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These parts are genuine too: ? ? ? ? Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ ? Owner - Operator Big Signal Ranch ¨C K9ZC Staunton, Illinois ? Owner ¨C Operator Villa Grand Piton ¨C J68HZ Soufriere, St. Lucia W.I. Rent it: Like us on Facebook! ? Moderator ¨C North American QRO Group at Groups.IO. ? email:? bill@... ? ?
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Re: Buyer beware! RD16HHF1
Well this is not entirely true.? You will get about the same performance out of the RD16HHF1 as that of the IRF510 by just replacement. Where the RD16HHF1 comes alive is when you also do other mods. ? There have been plenty of posts in this forum about the advantages using 1:4 transformers and others to perk up the RD16HHF1 sets. ? I think the real advantage of using the RD16HHF1 is 1) its much lower Gate capacitance that the IRF510 making it easier to match and flatten the power with frequency, and 2) it was designed for use at 12 volts, whereas the IRF510 comes alive in the 28+ volt range. ? There is a plethora of designs available to learn from.? See here? for starters: ? G6ALU ?? TF3LJ SoftRock? Open HPSDR? G6LBQ? G0IMX? VK5FE? MiniKits? Radio Kits? NT7S? ? This one on 6 meters¡ ? ? ? Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ ? Owner - Operator Big Signal Ranch ¨C K9ZC Staunton, Illinois ? Owner ¨C Operator Villa Grand Piton ¨C J68HZ Soufriere, St. Lucia W.I. Rent it: Like us on Facebook! ? Moderator ¨C North American QRO Group at Groups.IO. ? email:? bill@... ? ?
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From: [email protected] [mailto:[email protected]] On Behalf Of Jerry Gaffke via Groups.Io
Sent: Sunday, May 13, 2018 11:30 AM
To: [email protected]
Subject: Re: [BITX20] Buyer beware! RD16HHF1 ? Also, keep in mind that if you plan to move from the IRF510 to the RD16HHF1,?
the uBitx final should have some adjustments to the transformer ratios and such.
The RD16HHF1 is not quite a drop in replacement.
Jerry
On Sun, May 13, 2018 at 09:17 am, Jerry Gaffke wrote: Allison has quite a few posts here.
None have discouraged experimentation with the IRF510's.
Quite the contrary.
She did however suggest you get your RF parts from reliable vendors,
be they IRF510's or RD16HHF1's.
Jerry . . . ?
On Sun, May 13, 2018 at 08:54 am, Russ Hines wrote:
Gents and ladies, I don't post much as I'm a busy broadcast engineer.? But I try to read often.
Allison's post contains wisdom.
Education tends to be expensive.? If your goal is IRF R&D, then knock yourselves out.? You will go through a lot of parts, and likely as not, spend a lot more time and money in acquiring the knowledge and experience.? In the end, you'll know what a part can or cannot do.? If that's YOUR goal, great.
For myself, my time is worth something to me.? I think it's false economy of both my time and money to blow up a few dozen $0.50 parts, chasing issues created by the selection of an inferior part from an unreliable source, when one appropriately selected and sourced $4.75 part will accomplish MY goal - to use a piece of equipment that I built.? The former is not worth the hassle.
If you need a cliche, here's two:? I'd like to "not reinvent the wheel," but would much rather "stand on the shoulders of giants."
Two cents duly submitted.
73,
Russ Hines
WB8ZCC
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Reply to: russ@.
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I added variable BW to my uBITX by placing BB112 VVCs across C218, C219 and C220. ?I use the RX voltage varied by a 10K panel mounted pot on receive and the TX voltage on transmit to make the BB112s go to minimum capacity. ?I use individual 4.7K resistors to feed the control voltage to the caps. ?The bypass cap that the 4.7K resistors fan out from needs a bleeder resistor. ?I used 510K.
As the voltage on the caps is reduced the higher audio frequencies are reduced until the BW is probably 100Hz or so at 1 volt. ?The filter center frequency is very low, 200 Hz or so with my BFO setting.
The BB112 has about 500pf capacity at 1 volt applied.
Tom ?W1EAT
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Note: I used the wrong resistor (15K) and that reduced the audio way too much. I am now using a 10 Ohm resister and now its great!
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Re: SSB filter - adjust width to 23kHz
Yep, I had some wide digi modes to try on 10m, so it appears I'd have
to use SDR for those.
Anyway, thanks for reply.
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On Sun, May 13, 2018 at 9:42 PM, ajparent1/KB1GMX <kb1gmx@...> wrote: No. And did you really mean 23KHZ? That the width used for the old wide FM
15khz deviation.
Generally ladder filters for even 6-8khz are difficult at 12mhz, between
ripple and notches at
the edges its hard to get a decent filter. For 23Khz I'd go to the drawer
and get a 10.7mhz
or 21.4mhz filter as they can be had with 25khz bandwidth. However its not
going to fit well.
The small 4pole filter for those frequencies you would need two cascaded
with noticeable loss.
You would also have to get a wider filter for the 45mhz spot too.
Allison
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Thanks Allison. I forgot about the K2 and will check the schematic when I return home. One nice thing about the old MXM circuit was that it was continuously variable rather than the step system used in the K2. Both work beautifully. I was thinking that the continuous shift might work, until I went back to read your comment about adjusting the BFO as well. I should have realized that if there was a simple solution, someone would have done it already. Life is never quite as simple as I would like it to be and my self-taught electronics instructor is nearly always behind the curve.
Gary, KJ5VW
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Re: SSB filter - adjust width to 23kHz
No.? And did you really mean 23KHZ?? That the width used for the old wide FM 15khz deviation.
Generally ladder filters for even 6-8khz are difficult at 12mhz, between ripple and notches at
the edges its hard to get a decent filter.? For 23Khz I'd go to the drawer and get a 10.7mhz?
or 21.4mhz filter as they can be had with 25khz bandwidth.? However its not going to fit well.
The small 4pole filter for those frequencies you would need two cascaded with noticeable loss.
You would also have to get a wider filter for the 45mhz spot too.
Allison
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Re: Oops - variable bandwidth IF
Once the proper capacitance has been determined for 2800 Hz and 500 Hz
bandwidth, it should be possible to use fixed capacitors with diode, transistor,
MOSFET, or relay switching to select bandwidth.
Arv? K7HKL
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On Sun, May 13, 2018 at 1:34 PM, ajparent1/KB1GMX <kb1gmx@...> wrote: The hyperabrupt diodes can easily go from a 400pf down to 50 and there are smaller value diodes
for the 40- 250pf range.? They are not all that cheap.
The alternate is switching between two filters each tuned as desired.? Diodes or relays can do
the switching.? The advantage of doing that is the end transformers can be optimized for the filter
in question as the terminating impedance changes with bandwidth.
Allison
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Re: Oops - variable bandwidth IF
The hyperabrupt diodes can easily go from a 400pf down to 50 and there are smaller value diodes
for the 40- 250pf range.? They are not all that cheap.
The alternate is switching between two filters each tuned as desired.? Diodes or relays can do
the switching.? The advantage of doing that is the end transformers can be optimized for the filter
in question as the terminating impedance changes with bandwidth.
Allison
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Re: Variable uBitx IF bandwidth question
Gary,? if you need large type let us know.
Using Varicap diodes is do able as the Elecraft K2 does exactly that.
Allison
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Oops - variable bandwidth IF
Managed to get my thinking on the caps.backward...the current filter is already designed for SSB, so we would have to lower the cap value for CW filter, not increase. Reminds me I shouldn¡¯t do anything from memory. Basic issue remains, finding a varicap with sufficient shift in capacitance.
Gary, KJ5VW
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Yves Bernier VK2AUJ
K9HZ