Even if you drive the crap out of those power supply/motor switch IRF510¡¯s¡ without a lot of other mods they will still only put out 5 watts.? We¡¯ve been through this¡ ? ? 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: Thursday, April 19, 2018 11:06 PM
To: [email protected]
Subject: Re: [BITX20] Transmitter Mods ? The first post in this thread describes Howard simple solution to even out the power across bands:
? ??/g/BITX20/message/46616
A little bit more of this same cure applied to Q92,93,96,97 as suggested in post 46649
should make it even better.
I'd much prefer this over most of the other schemes proposed thus far.
Note that Howard is achieving this with the stock IRF510's.
Jerry, KE7ER
On Thu, Apr 19, 2018 at 08:52 pm, AA9GG wrote: I heard that some guys are switching in/out bias control pots for each band and adjusting them to maintain the same power on all bands. . . . ? On Thu, Apr 19, 2018 at 10:41 PM, Satish Chandorkar <satish.vu2snk1@...> wrote: How you propose to control the drive to be of 5 watts on all bands for your 70 W amplifier As the uBITX is giving much more power out put on lower bands? than on the higher bands
Satish
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Drive pots.? RV1.? See uBITx.net for the writeup. ? ? 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 AA9GG
Sent: Thursday, April 19, 2018 10:52 PM
To: [email protected]
Subject: Re: [BITX20] Transmitter Mods ? I heard that some guys are switching in/out bias control pots for each band and adjusting them to maintain the same power on all bands. ? On Thu, Apr 19, 2018 at 10:41 PM, Satish Chandorkar <satish.vu2snk1@...> wrote: How you propose to control the drive to be of 5 watts on all bands for your 70 W amplifier As the uBITX is giving much more power out put on lower bands? than on the higher bands
Satish
? On Fri, Apr 20, 2018 at 5:07 AM, Howard Fidel <sonic1@...> wrote: Actually, I would prefer to rewind the transformer with a center tap, and eliminate the chokes, feeding the DC to the center tap.
Z for L8, L9 should be >> then the output impedance which looks like the antenna impedance for the 1:1 transformer.
I am adding a 70 watt amplifier to my uBitx, so I just need 5 watts out on all bands to drive it. I doubt I will do much more, on the transmitter, but I will have to see how the amp behaves. I may to to better equalize the output level between the bands.
Howard
On 4/19/2018 2:37 PM, Jerry Gaffke via Groups.Io wrote:
The parallel resonance helps us to a point, though an ideal inductor would generally be better.
For example, if the inductor is self resonant at 14mhz, we'd see much more power out on 20m
than we see on 10m.? I'd prefer to keep gain vs freq somewhat controlled and predicatable.
The caps are easier to add, easier to obtain, have a higher self resonance:
? ??
Maybe add 220pF caps across all six of the 22 ohm emitter resistors, and forget the inductor?
Then add a variable cap somewhere around Q90 that can be tweaked to give the flattest response,
that setting may vary given your particular 2n3904 transistor characteristics.?
?
But the inductor in series with the negative feedback is a good idea.
If this can all be done with just 3 extra components and get good enough results across
the different uBitx's out there, I'm fine with that.
One other issue:
As Henning notes in post 45035,?the chokes L8 and L9 are best wound on a single core:
See the discussion below figure 4 on this webpage, where he discusses how the bifiliar
approach works, though he does not discuss the individual choke solution:
? ??
I was seeing significantly worse results in how the uBitx final worked compared
to the WA2EBY final in my LTSpice simulation, could be due to these chokes.
? ??/g/BITX20/topic/9615903
I may have to play with that further, not obvious to me how or if the individual chokes
at L8, L9 would impact the results..
Jerry, KE7ER
On Thu, Apr 19, 2018 at 11:00 am, Jerry Gaffke wrote: Good question.
It's a parallel resonance:??
? ??
?
?
--
Paul Mateer, AA9GG
Elan Engineering Corp.
NAQCC 3123, SKCC 4628
|
The first post in this thread describes Howard simple solution to even out the power across bands: ? ?? /g/BITX20/message/46616A little bit more of this same cure applied to Q92,93,96,97 as suggested in post 46649 should make it even better. I'd much prefer this over most of the other schemes proposed thus far. Note that Howard is achieving this with the stock IRF510's. Jerry, KE7ER
On Thu, Apr 19, 2018 at 08:52 pm, AA9GG wrote:
I heard that some guys are switching in/out bias control pots for each band and adjusting them to maintain the same power on all bands.
. . .
?
On Thu, Apr 19, 2018 at 10:41 PM, Satish Chandorkar <satish.vu2snk1@...> wrote:
How you propose to control the drive to be of 5 watts on all bands for your 70 W amplifier
As the uBITX is giving much more power out put on lower bands? than on the higher bands
Satish
?
|
I heard that some guys are switching in/out bias control pots for each band and adjusting them to maintain the same power on all bands.
On Thu, Apr 19, 2018 at 10:41 PM, Satish Chandorkar <satish.vu2snk1@...> wrote: How you propose to control the drive to be of 5 watts on all bands for your 70 W amplifier
As the uBITX is giving much more power out put on lower bands? than on the higher bands Satish
-- Paul Mateer, AA9GG
Elan Engineering Corp.
NAQCC 3123, SKCC 4628
|
|
|
How you propose to control the drive to be of 5 watts on all bands for your 70 W amplifier
As the uBITX is giving much more power out put on lower bands? than on the higher bands Satish
On Fri, Apr 20, 2018 at 5:07 AM, Howard Fidel <sonic1@...> wrote:
Actually, I would prefer to rewind the
transformer with a center tap, and eliminate the chokes, feeding
the DC to the center tap.
Z for L8, L9 should be >> then the output impedance which
looks like the antenna impedance for the 1:1 transformer.
I am adding a 70 watt amplifier to my uBitx, so I just need 5
watts out on all bands to drive it. I doubt I will do much more,
on the transmitter, but I will have to see how the amp behaves. I
may to to better equalize the output level between the bands.
Howard
On 4/19/2018 2:37 PM, Jerry Gaffke via Groups.Io wrote:
The parallel
resonance helps us to a point, though an ideal inductor would
generally be better.
For example, if the inductor is self resonant at 14mhz, we'd see
much more power out on 20m
than we see on 10m.? I'd prefer to keep gain vs freq somewhat
controlled and predicatable.
The caps are easier to add, easier to obtain, have a higher self
resonance:
? ??
Maybe add 220pF caps across all six of the 22 ohm emitter
resistors, and forget the inductor?
Then add a variable cap somewhere around Q90 that can be tweaked
to give the flattest response,
that setting may vary given your particular 2n3904 transistor
characteristics.?
?
But the inductor in series with the negative feedback is a good
idea.
If this can all be done with just 3 extra components and get good
enough results across
the different uBitx's out there, I'm fine with that.
One other issue:
As Henning notes in post 45035,?the chokes L8 and L9 are best
wound on a single core:
See the discussion below figure 4 on this webpage, where he
discusses how the bifiliar
approach works, though he does not discuss the individual choke
solution:
? ??
I was seeing significantly worse results in how the uBitx final
worked compared
to the WA2EBY final in my LTSpice simulation, could be due to
these chokes.
? ??/g/BITX20/topic/9615903
I may have to play with that further, not obvious to me how or if
the individual chokes
at L8, L9 would impact the results..
Jerry, KE7ER
On Thu, Apr 19, 2018 at 11:00 am, Jerry Gaffke wrote:
Good question.
It's a parallel resonance:??
? ??
|
Just reading this initial post again. I was confused by it because its so different from my experience. I might have different conditions though. My antenna is balance and is a loop. A full loop on 80 meters. For transmitting I have a tuner,? but with or without it, and with different feed methds, such as coax, 450 open line, and 4 to one baluns, I've had excellent results with this tuner. I am in a low noise area. But, your problems seem to all be related to high signal levels, and possibly high noise levels . If that is what your antenna is receiving, I've had lower noise with my full waive 265 foot loop than any other type of antenna. It an amazing way to go. Of course, a dipole would be a much less efficient version of my antenna, and could display the lower noise attributes. Its definitely the way to go.? --
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Re: Transmit indicator light.
Hi Gary. ? I¡¯ve been kind of busy and just got around to checking out this link.? It didn¡¯t lead me to anything useful.? ? Regards. ? Max K 4 O D S. ? I've Never Lost the Wonder. ? Antique Electronics Site: ? ?
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From: [email protected] [mailto:[email protected]] On Behalf Of Gary Anderson
Sent: Thursday, April 19, 2018 6:03 AM
To: [email protected]
Subject: Re: [BITX20] Transmit indicator light. ? Hi Max,
I'm assuming that you have an enclosure from Sunil (VU3SUA) by the description.? He has pictures on his website showing how he has done the? RX/TX LED wire-up.
The website is??the pictures are the second and third from the last.
He is picking up the 12V RX and TX control signals from the uBITX RX/TX relay by soldering wires to the bottom of the uBITX PCB.? He also picks up the ground from the relay.? He then routes 3 wires (RX,TX,GND) to a small prototype board with series current limiting resistors on RX and TX.? No reason you couldn't put your resistors anywhere along that route.? I would have put them right on the PCB.
Regards,
Gary
AG5TX
|
Hi Jacob,
Yes, I have done the RF gain mod and it works well - but still the tuner still makes a big difference.
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On 20 Apr 2018, at 12:05 pm, Jacob Farnes via Groups.Io < kk6jtl@...> wrote:
The Bitx40 is my favorite radio to listen with once I did the RF gain mod via the two pin holes and cut the trace on the underside. /g/BITX20/message/26490I shouldn't have tombstoned the 10-ohm surface mount resistor. Just needed 2 wires and a potentiometer to be a variable resistor. Nice and quiet most days.
|
I am using his new AGC circuit. It works well. You still get a slight pop when an extremely strong signal first comes on but it is very short and, to me at least, not annoying at all. You may want to lower the 1Mohm resistor to something smaller to decrease the pop, i.e. decrease the attack time. The next time I open the case I'm going to try 500K. tim ab0wr On Thu, 19 Apr 2018 19:16:04 -0700 "Michael Shreeve" <shreevester@...> wrote: I'm going to try ND6Ts new AGC version. He seems to think its the way
to go. Its here. My MOSFET's are on the way.
On Thu, Apr 19, 2018 at 7:05 PM, Jacob Farnes via Groups.Io <
kk6jtl@...> wrote:
The Bitx40 is my favorite radio to listen with once I did the RF
gain mod via the two pin holes and cut the trace on the underside.
/g/BITX20/message/26490
I shouldn't have tombstoned the 10-ohm surface mount resistor. Just
needed 2 wires and a potentiometer to be a variable resistor. Nice
and quiet most days.
|
What's the problem with the performance?
|
It's sure worth the effort to build & install it. ?Made an S9++ signal into one that didn't hurt the ears and an S2 signal was readable at the same setting of the volume control. ?Thanks ND6T for a very workable AGC circuit!
Jim, W0EB
Jim, W0EB
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On Apr 19, 2018, at 9:16 PM, Michael Shreeve < shreevester@...> wrote: I'm going to try ND6Ts new AGC version. He seems to think its the way to go. Its here. My MOSFET's are on the way.?
|
Re: anybody tried softrock and hdsdr with Ubitx?
thanks Bill, Paul
On Thursday, April 19, 2018, 6:46:47 PM CDT, K9HZ <bill@...> wrote:
Yeah Ian did¡ and he has a video on Youtube using it¡ ? ? 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@... ? ?
From: [email protected] [mailto:[email protected]] On Behalf Of Paul Schumacher via Groups.Io
Sent: Thursday, April 19, 2018 11:50 AM
To: [email protected]
Subject: Re: [BITX20] anybody tried softrock and hdsdr with Ubitx? ? Has anyone tried a softrock and hdsdr with Ubitx to get the spectrum and waterfall display?? (or something similar?) ? If so, can you please describe how to go about doing it?
|
I'm going to try ND6Ts new AGC version. He seems to think its the way to go. Its here. My MOSFET's are on the way.?
On Thu, Apr 19, 2018 at 7:05 PM, Jacob Farnes via Groups.Io <kk6jtl@...> wrote: The Bitx40 is my favorite radio to listen with once I did the RF gain mod via the two pin holes and cut the trace on the underside.
/g/BITX20/message/26490
I shouldn't have tombstoned the 10-ohm surface mount resistor. Just needed 2 wires and a potentiometer to be a variable resistor. Nice and quiet most days.
|
The Bitx40 is my favorite radio to listen with once I did the RF gain mod via the two pin holes and cut the trace on the underside.
/g/BITX20/message/26490
I shouldn't have tombstoned the 10-ohm surface mount resistor. Just needed 2 wires and a potentiometer to be a variable resistor. Nice and quiet most days.
|
You need to take a cigar, coat it with epoxy and a bit of fiberglass,?
use that for your mike barrel.
Jerry
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On Thu, Apr 19, 2018 at 05:34 pm, <tony.vasile@...> wrote:
AAAAAAND here's the pic!
?
Tony KB9A?
|
Re: UbitX I2C GPIO Breakouts?
I've been using I2C from the w0eb radi2cino to the lcd for a couple of weeks. I'm not seeing any kind of slow response. If I read right it takes about 100us to do an analogRead(). On a 100kbps I2C bus it would take about 80Us for 8bits or 160us for a two byte word. Not a big difference in speed, at least for reading data. tim ab0wr On Thu, 19 Apr 2018 16:44:22 -0700 "NNicholas via Groups.Io" <NNicholas@...> wrote: I have used these chips on many projects and used them to drive led
displays, but for this application,? given the slower response of the
I2C serial bus, I would stick with the given direct I/O driven LCD
display and use the I2C serial to communicate with a second arduino,
to add more functions. That way you keep speed, have true
multitasking going on, and not only double the io, but you double
memory. I plan to add an custom auto antenna tuner to mine, and a 100
watt amplifier , all in the same enclosure. I will be using a second
arduino based processor to control both the filtering and switching
of the amplifier in and out, and seek and search for best antenna
match without having to interrupt the radio operations. That way,
when auto tune is turned on, the amp will drop out to low power , the
antenna will tune, and then return to the original settings. Like
wise as the radio is turned to various bands, the pi filters in the
amp can automatically switch with the band. Nick N8GIR
|
Hi all,
I just had a thought about new users of the uBitx and the Bitx40.
I have both of these fine rigs but with my good antenna - a??at 30 feet - the receivers are swamped by noise and big signals on 40 metres.
When I tested just now a 59+ 10 signal on my IC-7300 was unreadable on the Bitexes with the big antenna (which has a low SWR at 40 metres) because of noise. With an antenna of just 6 feet of wire in the shack the signal was readable (but weak) on the Bitexes!
I usually use a tuner beween the antenna and the Bitexes - that works fine to tame the noise. Also I have fitted an RF control to the Bitx40 that helps quieten big signals.
But if you have lots of noise in the receiver and no tuner - try a smaller antenna on receive (it will be no good for transmitting). If that improves things maybe you need a tuner or an RF control.
73s John V2VOL
|
Re: Extension cables for display/Raduino
Also see this article:? /g/BITX20/topic/7573243It includes a link to a nice article (PDF) by Al Duncan VE3RRD showing how to make an extension cable from an old computer IDE cable (flat ribbon cable).
-Jonathan
|
AAAAAAND here's the pic!
Tony KB9A?
Here is my cigar-box uBitx with a wooden dowel Mic using the kit electret mix element and the Microsoft.
Tony, KB9A?
On Thu, Apr 19, 2018, 5:18 PM Gary Shriver < gshriver@...> wrote: I know it¡¯s there somewhere!! ? ![]()
? ? ?
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K9HZ
AA9GG
Satish Chandorkar
Michael Shreeve
Jim Sheldon
Jonathan
