Date   
Re: New version of TFT Touchscreen based VFO-BFO for uBitx

freefuel@...
 

is this a nre controller board, or using the standard Arduino mega board? 

-Justin N2TOH 

Re: New version of TFT Touchscreen based VFO-BFO for uBitx

Joe
 

Standard atmega 2560


On Sun, Aug 12, 2018 at 3:23 PM <freefuel@...> wrote:
is this a nre controller board, or using the standard Arduino mega board? 

-Justin N2TOH 

Re: Harmonics

Gordon Gibby <ggibby@...>
 

The first version of the document for adding an external relay daughterboard is attached.   Note that I switched to externally switching the INPUTS to the low pass filters, simply because the way Ashar laid out the v3 and v4 boards, it results in easier and shorter signal paths for 3 out of 4 filters, to the daughterboard.   The existing relays switch the outputs.   By making a couple of cuts in some of the wires, you REALLY help to disconnect the parasitic capacitances.  


It ends up being five signal lines that have to be cut, and extended to the daughterboard  (and a ground of course).   I think they are all fairly easy to get at with a drill or exacto or Dremel tool.   Then there are four relay control lines (TX and KT1, KT2, KT3) that just have to be extended to the daughterboard without any cutting.   I suggest that a bit of shielding be used on those (even if just running a ground wire lazily coiled around them), even though they are bypassed to ground by capacitors, just to avoid any pickup through the relay coils.   I also put some inductors in series with the relay coils to futher decouple them.


Beware the Panasonic relay is laid out slightly differently -- NC and NO have swapped positions from the ubitx relays!!     This is correctly handled on my schematic and printed circuit board, and explained twice in the documentation.    


I'll check over the PCB a bit more before releasing any Gerbers.   Also some  of you might see some stupid goof I've made!!   


Of course, there are several approaches to fixing this issue --- one of which is as pointed out to reduce the filter impedance to reduce the effects of the parasitic capacitances.    I just don't like rebuilding sections of existing circuitry and I was HOPING to take more advantage of the real filtering Ashar put in there!    But to each his own --- if this helps, fine, it not, no matter!!


Cheers,


Gordon 




From: BITX20@groups.io <BITX20@groups.io> on behalf of David Posthuma <davep@...>
Sent: Sunday, August 12, 2018 1:56 PM
To: BITX20@groups.io
Subject: Re: [BITX20] Harmonics
 

My enclosure is only 3-inches tall. I know many uBitx users have enclosures that are even shorter. I would encourage any additional boards make use of a “sandwich” approach…although I understand this approach might introduce capacitance issues. See example below…

 

Image result for HF low-pass sandwich boards

 

David A Posthuma, WD8PUO

 

From: BITX20@groups.io <BITX20@groups.io> On Behalf Of F1BFU - Fr - 79
Sent: Sunday, August 12, 2018 12:15 PM
To: BITX20@groups.io
Subject: Re: [BITX20] Harmonics

 

Hello Glenn

 

Here is the photo with the QRPLabs relay card at the real-world level.

 

Gilles F1BFU / FR

IMAG0379.jpg

 

Le dim. 12 août 2018 à 11:46, Glenn <glennp@...> a écrit :

Gordon, hope I have the intent on your PCB correct. If not ignore me.......

What about making the PCB so it stands vertically against the edge of the uBITX main pcb, adjacent to the LPF section. The new relays will end up above the uBITX board.  

Cut the existing tracks as per Allisons information.

Scrape the resist off under the uBITX board in the area of the LPF and about 2-3mm wide. ie GND plane.

Your new board can then but upto the uBITX board and be seam soldered to the uBITX underneath.

Very short (5mm) wire link from the end of each LPF to your board.

Glenn vk3pe

Re: BITX QSO Afternoon/Evening, Sunday, August 12, 3PM & 7PM Local Time, 7277 kHz in North America, 7177 kHz elsewhere.

John P
 

On Sun, Aug 12, 2018 at 10:08 AM, Jack Purdum wrote:
I think my antenna is somewhere in WV.
They have some nice mountaintops to operate from there! Go to the antenna! Seriously, hope you get back on soon!
 
--
John - WA2FZW

Re: Three cheers for the uBITX! Keeping problems in perspective....

Dexter N Muir
 

Heartily seconded! My efforts in that world have been brick-walled by QRM and age (can't get up on roof or ladder now) at the BITX40 stage, but I'm still keenly agog at the expertise and development by the community. Borrowed from my personal situation, advice to Government applicable here; "It takes a village to raise a child."

Re: BITX QSO Afternoon/Evening, Sunday, August 12, 3PM & 7PM Local Time, 7277 kHz in North America, 7177 kHz elsewhere.

kc1at
 

"T" storm came thru a of couple hours ago. Still struggling with the static crashes. Guess I should have done the AGC mod. Got that on the list now. I'll try around 7PM but the broadcasters are coming in now on 7284.

don

ubitx compared to Elecraft or Xiegu for spurs #ubitx

 

Has anyone run tests on the popular Elecraft KX3 or the Xiegu 5105 for spurs and harmonics?  How do they compare to the uBITX?
Thanks,
Jim W0CHL

Re: Spurs - BPF fix? #ubitx

ulf.jagfors@...
 

After the latest information about the spur problem my built of v3 stalled again. I am working on a metal enclosure from an old project and of course it is important that the space is enough in the box and front panel for all possible needed mods. For a while I concentrated on the output issue and AGC/ALC/POP/S-meter and SWR fix. But I now realize that more must be done on the spur/harmonic side and space for more additional cards must be counted for. Phuuu.

Anyhow I am grateful for all suggestions how to solve the problem that crop up more or less   on daily bases. But I have to say that it must be nearly impossible for the average uBITX owner to really sort out what could be done in a quick fix way. Who will come up with a bandpass filter design and a channel to sell it to people who do not have a spec or a network analyzer.  Now I am happy to have both, so I can spend endless nights to wind coils, etch cards and test the performance something I did as new amateur back in the fifties. But that I do not want to do any longer. House, garden, dogs and family takes its time toll also for a retired amateur.

So, what could be found on the market for a decent price to perhaps solve the problem.

I found it on RV3FY web site some gadgets that might be the quick solution to these spur/harmonic problems, perhaps once for all.

He sells in kit form following complete filter units for prices around $30 plus postal registered shipping. But you need PayPal for paying him.

https://www.rv3yf.store/bandpass-and-lowpass-filter

I have bought following low pass filter board with six relay switched links

“Universal Lowpass filters for HF Amateur Transceiver (LPF). 9 bands

It has six links to cover all harmonics for all bands up to 30 Mhz. It could perhaps replace the on-board filter chain that has cause some discussions about poor crosstalk performances. And it should be able to handle up to 10-watt output without any problem.

I have also ordered a complete nine band bandpass filter with all nine bands represented.

“Universal Bandpass Filters for HF Transceivers "BPF-9" (9bands), RFamp & ATT

 It is tunable by ferrite core coils and have an ATT function as well as a half watt RF driver. I now have the stupid idea that this unit could possibly be inserted after Q90 at RV1. If the RF driver is good enough it could perhaps also replace some or all 2N 904 drivers to the IRF PA.  As it has an ATT function one could perhaps also break up the RX lines and let the RX work throw the Bandpass filters.

The drawback is of course the control of the filters. The easiest is of course to have a mechanical rotary switch on the front panel to manually choose band of interest.

The best is if somebody could come up with a mod card plus SW to take the frequency information from the Arduino and let a relay driver chip control the 2x6 and 2x9 12 volt relays. I am an analogue man so I can not do that but there are plenty of code hackers out here on the different lists, so it could be done.

A third option is to use a separate frequency detector a “Band decoder sequencer” which detects the frequency and activate the right relay control output. Such unit can be bought from following Web page. It costs about $57 plus shipping. Then you do not need to involve Arduino in this process.

http://dn-radio.com/units/dnb-b10

I fully realize that it is not as easy as I have outlined here but at least this is the way I will try and when ready I will report the outcome.  And perhaps somebody could take up my ideas and make something out of it faster than I can.

Ulf, sm0cgl in Stockholm

 

 

Tiny SWR Bridge

W3JDR
 

This might be of interest to the group, so I published it on my web site:

www.w3jdr.com

W3JDR
Joe

Re: Hello all

Timothy Fidler
 

David the site is mainly for the uBitx  multiband and the Bitx40 which is either VFO or "DDS" controlled so many of your comments won't make a lot of sense to those who purchased these pre stuffed boards as in SMD.  It is prolly a bit late to mention this  but  Fred at Far Circuits in US sells a Bitx board set of etched PCBs. you could possibly get him to part with the main bitx board for $15 USD. The other board is the class A power amp which can easily  be done on islanded copper clad board.  AGC can be done with the TDA7062A or AT  chips which have an AGC pin built in .. you sink it to GND with an NPN transistor to mute the chip.  one option there is found by studying the MST3 schematic on the ozQRP.com site of Leon in NSW. go to documents section (or even look at the old MST2 board under the archive documents section) Obviously 2 or four small signal diodes and a ceramic capacitor will give you AGC volts from further back in the radio for  RF agc..... That TDA is hard to get from normal suppliers , Farnell has it but it is all over the PRC ebay internet  at low prices. the TDA without the A or AT suffix does not have the mute pin.  cheers TEF

Re: Hello all

Timothy Fidler
 

A thought occurs on a 20/40 m Bitx analogue dual band if you want to keep going . There are three parts that need switching.  RF in.   the clean up filters after the RF mixing and the final LPF.  those first two could potentially be done by a second ceramic RF variable capacitor for high Q  switched in by a small signal diode to ground to go to Low band. the  LPF because of the power,would generally have to be relay switched but the relay is only powerd on on one band , not both (two SPDT relays, one per filter end).  A Farhan gave  and still has a design on the internet similar to this for 40/20m transceiver  but many many relays he admits as much.  You also need to design the carrier inject osc for LSB/USB using a puller inductor and capacitor for low and variable trimmer capacitor for high. For the vfo,  you can either make a WIDELY tuning VFO with fine control via a trimmer or  use a dual gang tuning capacitor and two vfos and switch in on or other by  having an A not B an B not A power supply arrangement.  A Farhan advocated he latter method I guess beccause relay switching of a single capacitor is problematical .  He used a fet plus buffer transistors VFO design. There is no "Best IF" for this but 10M is popular as an IF frequency as it works for both 20 and 40 m and xtals are cheap and easy to find..... TEF

Re: Substitutions or Sourcing components

Timothy Fidler
 

Diz at Kits and Parts in the US has a lot of  Rf  semi stuff,  as well as magnetic cores he is famous for.

Furturlec.com has thousands of crystal frequencies and can also supply 2n3866 if you ask him .. so he told me. He used to list it but perhaps not much  foot traffic.  Opinions vary about Alan's operation (north of "Synney" , not in the US though he has USD prices- he pulls stuff out of warehouses in Thailand to make up orders) . He is also very cheap as in 50c US per crystal for example.  I have had zero problems but it seems others have but then often there is a background like trying to order zero stock parts and so on and the fool then goes and  tries to flame the supplier on some BBS.  He does small orders. NB  the 2n4227 is a very similar CATV transistor ie. good to 80-100 Mhz plus  to the 2N3866 and in general will slot straight in as  a replacement. 

Fred at Far circuits in Chicago  not only sells PCBs but also has  quite a component list including a few common small size cores in both iron powder  and ferrite. I believe he has some IF cans but he does not list them. Pays to ask.

Re: BITX QSO Afternoon/Evening, Sunday, August 12, 3PM & 7PM Local Time, 7277 kHz in North America, 7177 kHz elsewhere.

John P
 

Calling CQ on 7277. Nothing but noise so far!
--
John - WA2FZW

Re: Sunday

Timothy Fidler
 

Some of the confusion on this thread arises from the fact that the early poster may have been using a class A RF final on an normal analogue Bitx.  Getting more than 4 W out of these at 13.8V supply is  a bit of an ask.

Others are talking of  Class B uBitx outputs with two IRF510s  run at unknown supply voltage. The STD build is supposed to give 10W out,  which is believable . There was a similar design from Hendricks kits .. output transformer was different.  The recommended setting bias to give no more than 12watts at 12V nominal supply because of spatter issues.  But they did admit in the build book that 15W RF out  without IRF destruction or life limiting was possible.

Re: Substitutions

Timothy Fidler
 

IMHO AF should still leave that old design up as it has some interesting points,  including the idea of a dual band VFO with one tuning capacitor...(as well as an LSB/USB carrier injection osc which is voltage switched.)   TEF

Re: BITX QSO Afternoon/Evening, Sunday, August 12, 3PM & 7PM Local Time, 7277 kHz in North America, 7177 kHz elsewhere.

John P
 

Somebody's rag chewing on 7277; don't think it's a BitX person. I'm going to try "CQ BX" on FT-8.
--
John - WA2FZW

Re: Substitutions

Timothy Fidler
 

DS as per my reply to GY3rp you can get pre etched boards for he old Bitx frm Fred at Far Circuits . He also does the 75m  SSB board by Weber which is essentially a Bitx but using  CMOS analogue switch switching.  Latter board is eight USD. BEWaRE you have to source the IF cans for the post mixer filter.  Now hard to get. This latter board can be moved over to 40m I have had that in writing from Weber. Ditch the 9M IF frequency if you use it. Use 10M , much more practical. Maybe 9M IF crystals cab be had in India but try finding them at Reas price in US or Australia.  The Weber PTO VFO.design ie permeabilty tuned . .. I would not go there it looks the work of the devil mechanically . There are much better buffered VFO designs from Ashan  Farhan for example.  On the Weber board the power amp is integrated.  An 2n3866 subs on the driver would make a world of difference to power output.  have a fish around on my other replies as to where to get this cheap (and not fake). Diz the toroid king, or Fred at Far Circuits can supply.  Without this as the driver , the IRF can barely make 2 Watts.  With it it will go closer to 5 W.  before you try to juice up this PCB with more volts than say 13 CHECK ALL the component specs.  I can't remember if Fred splits out the power rail to the IRF510.. if he does then you can do more things. Remember an anti stuff up 2A (say) schottky diode on the power rail. You don't want 12hrs' work down the drain by some fool hooking it up back Ass-wards.

Re: ubitx compared to Elecraft or Xiegu for spurs #ubitx

VE3MIC
 

Has anyone looked at the Yaesu FT-991 for spectral purity? :)


On Sun, Aug 12, 2018 at 5:07 PM, Jim Reagan
<jimreagans@...> wrote:
Has anyone run tests on the popular Elecraft KX3 or the Xiegu 5105 for spurs and harmonics?  How do they compare to the uBITX?
Thanks,
Jim W0CHL

Re: ubitx compared to Elecraft or Xiegu for spurs #ubitx

ajparent1/KB1GMX <kb1gmx@...>
 

My .02 on testing everything in sight...

Send me one of each and a pot load of money I'll write a report. 
You can read the manual as the specs called out are accurate.
That will save a lot on currency.

Why is this in the Bitx at all?

Allison

Re: Sunday

Kevin Rea
 

I am doing cw on 40 meters at the moment, i get 12 watts out.
i get about the same on cw on 20 meters.

kevin rea
lancaster, calif.
k6rea