Ken,
Thanks for the tip! I'll let this be my test.
--
Stephen, KO4CVU
|
Re: Farhan's Analog Again The Daylight Radio
Bob, The tranformers can be bifilar, with 10 turns of a twisted pair of 28 swg over an FT37-43 toroid.? The transformer is marked as trifilar in the circuit because I have a box full of them from HF Signals. I just leave one winding unused. - f
On Fri, Aug 5, 2022, 11:34 PM Bob Benedict, KD8CGH < rkayakr@...> wrote: The plans are clear to me except for T1 and T2. How are the trifiliar transformers wound? How many turns on what size toroid? Are 2 and 6 really unconnected?
--
? 73
??? Bob? KD8CGH
|
You can edit your response and include the #hashtag in the subject line of your response when you reply to an individual email.
I wonder what the 'subgroup' function offers - I haven't had a chance to investigate it yet
Ken, N2VIP
toggle quoted message
Show quoted text
On Aug 5, 2022, at 14:17, Stephen KO4CVU <goinfishin1952@...> wrote:
Unfortunately, I haven't figured out how to put a #HASHTAG on a reply to an exisitng post yet ... but when I do, I will.
|
Just got a 256 GB uSD for my Pi.? Still waiting for the sBit itself to ship - ordered it a week ago,
Gerry Sherman
Sent by the Thunderbird
|
Re: Does anyone have the KD8CEC 5 inch nextion files?
Check the file section under AJ6CU. The only problem might depend on how new your screen is. Those files were good with the Nextions with the firmware of several years ago. If you get an error when you try to upload it let me know and I will create a new set for the most recent firmware.?
73
Mark
AJ6CU
|
Re: sBitx antenna-first warning
I forgot to say, the only antenna using rg6u quad shield is my vertical. the rest is using ladderline. I have a simple balun to help match impedances and my simple match unit i built.
73 David ac9xh
On Friday, August 5, 2022 at 05:57:31 PM EDT, david todd via groups.io <ac9xh@...> wrote:
I used to use an ammeter and a neon bulb. tune to max on both. Also,It helps to cut the antenna to band resonance. I have several antennas ,one for each band i run, also i use a homebrew vertical 3 ft above ground with no radials and this one is the one i use? from 80 to 6 meters. i actually have to use my homebrew match for it.
All my antennas have been cut for band resonance, i dont use a commercial match except for my ubitx v6 which i installed inside of it.. For my other ubitxs and bitxsi use a homebrew match using 15 turns of #22 gauge wire with a 100 pf variable? to help match to the antenna and a $5 dollar swr meter inline. Ive used this setup for all my radios, and including ubitx v3,v6,bitx40, patcomm pc 500, argonaut 509,.
Sometimes, if your antenna is crappy or not designed properly, or have feedline problems etc ,you can"tune" the "antenna tuner and receive almost a 1:1 and never get out very well because of the false sense of security with an antenna tuner. I dont like the term tuner We all use, because you are not tuning the antenna,but just creating a compatible match from radio to cable.
You might check your coax,fittings and antenna connections. With an open circuit(break in the coax at the fitting or antenna)you will take awhile to get any match impedance wise. If you have an auto antenna match, and it starts clicking for over 6 to 14 seconds, more than likely an open somewhere or a really big problem with your antenna, .I personally experienced this with the ldg z100. had a cable break right at the fitting.
Just my personal take of it all. And i have never popped a final on any of my ubitxs or bitxs.
73 David ac9xh
On Wednesday, August 3, 2022 at 03:09:45 PM EDT, Jerry Gaffke via groups.io <jgaffke@...> wrote:
Here is one of many posts from Allison that are worth reviewing, mentions the 6m 225W power amp she built using 4+4 IRF510's in push-pull. The whole thread is worth a read. ?? /g/BITX20/message/22597She has been contributing to the forum for some time now: ?? /g/BITX20/message/14514?? /g/BITX20/message/869Just plugging a new fet into the sBitx likely won't solve anything. The circuit around it should be designed specifically for that part for good performance. Jerry, KE7ER
On Wed, Aug 3, 2022 at 10:14 AM, Jerry Gaffke wrote:
The IRF510 can work dependably, Allison reports years of success with HF amps at 40W push-pull,
surviving everything from accidental open antenna connections to dead shorts.
In posts to this forum from several years ago, Allison went into plenty of detail.
She even used them on 6m at several hundred watts (with bunches of them in parallel).
|
Re: sBitx antenna-first warning
I used to use an ammeter and a neon bulb. tune to max on both. Also,It helps to cut the antenna to band resonance. I have several antennas ,one for each band i run, also i use a homebrew vertical 3 ft above ground with no radials and this one is the one i use? from 80 to 6 meters. i actually have to use my homebrew match for it.
All my antennas have been cut for band resonance, i dont use a commercial match except for my ubitx v6 which i installed inside of it.. For my other ubitxs and bitxsi use a homebrew match using 15 turns of #22 gauge wire with a 100 pf variable? to help match to the antenna and a $5 dollar swr meter inline. Ive used this setup for all my radios, and including ubitx v3,v6,bitx40, patcomm pc 500, argonaut 509,.
Sometimes, if your antenna is crappy or not designed properly, or have feedline problems etc ,you can"tune" the "antenna tuner and receive almost a 1:1 and never get out very well because of the false sense of security with an antenna tuner. I dont like the term tuner We all use, because you are not tuning the antenna,but just creating a compatible match from radio to cable.
You might check your coax,fittings and antenna connections. With an open circuit(break in the coax at the fitting or antenna)you will take awhile to get any match impedance wise. If you have an auto antenna match, and it starts clicking for over 6 to 14 seconds, more than likely an open somewhere or a really big problem with your antenna, .I personally experienced this with the ldg z100. had a cable break right at the fitting.
Just my personal take of it all. And i have never popped a final on any of my ubitxs or bitxs.
73 David ac9xh
On Wednesday, August 3, 2022 at 03:09:45 PM EDT, Jerry Gaffke via groups.io <jgaffke@...> wrote:
Here is one of many posts from Allison that are worth reviewing, mentions the 6m 225W power amp she built using 4+4 IRF510's in push-pull. The whole thread is worth a read. ?? /g/BITX20/message/22597She has been contributing to the forum for some time now: ?? /g/BITX20/message/14514?? /g/BITX20/message/869Just plugging a new fet into the sBitx likely won't solve anything. The circuit around it should be designed specifically for that part for good performance. Jerry, KE7ER
On Wed, Aug 3, 2022 at 10:14 AM, Jerry Gaffke wrote:
The IRF510 can work dependably, Allison reports years of success with HF amps at 40W push-pull,
surviving everything from accidental open antenna connections to dead shorts.
In posts to this forum from several years ago, Allison went into plenty of detail.
She even used them on 6m at several hundred watts (with bunches of them in parallel).
|
Re: Ubitx ver 3 ssb transmit question
There was a setup doc that said initial current should be between 470-500mA. Adjust one pot for 100mA more. Stop. Do the other one for a total of 200 mA more than initial current. That makes more sense now.
|
Re: Jacks T41 Board Sets Available
I¡¯ve been following Jack Purdum¡¯s T41 SDR project on his group. Looks like they have a few board sets left for sale from their group buy activities. You can get them from K9HZ. Eight boards for $6.15 plus shipping.
MRM
--
¡_. _._
|
Does anyone have the KD8CEC 5 inch nextion files?
looking to upgrade my uBITX with the KD8CEC software, and all works well on the smaller Nextion, but want to upgrade it to the 5 inch display,
and I need the file.
thanks
N2AIE
Vince
|
I totally agree with Stephen and like the #HASHTAG idea.? I own 6 uBitx (2 v4, 1 v5, and 3 v6) and have an sBitx.
73
Evan
AC9TU
|
Owning three uBITX's (two v6's and one v5) with a sBITX kit due next week, I would prefer that there be just one group, the BITX20, for all of them.
BUT?if we could all religiously apply appropriate #HASHTAGS to our original posts, we would make the group much more useful.
Looking at the #HASHTAG option, I just learned that I can choose to filter out or be alerted for a post with a certain #HASHTAG! That way, I can filter out posts that don't interest me and focus on those pertinent to my units.
Unfortunately, I haven't figured out how to put a #HASHTAG on a reply to an exisitng post yet ... but when I do, I will.
--
Stephen, KO4CVU
|
Re: Amplifier output calculations (was sBitx antenna-first warning)
Ashar,
That is not the output impedance of the amplifier, nor is it the
effective load on the power supply.
Almost all RF power amplifiers are specified for a 50 ohm load.? 40
watts to a 50 ohm load gives an output voltage of SQR(Pout*Rload) =
44.7Vrms = 63.2Vpeak and output current of SQR(Pout/Rload) =
0.89Arms = 1.26Apeak.? This clearly is going through a transformer
if the PA power source is 12V.? Assuming that this is the design
maximum output power, in a push-pull class B amplifier (necessary
for SSB) of perfect efficiency (no loss in the device
on-resistance), the voltage must be transformed from 12V to 63.2V
> turns ratio of 1:5.26 (the actual transformer would be half of
this ratio due to the 2 push-pull legs.? If a single device is used
it gets even more complicated as it has to effectively drive both
halves of the output from one half-phase).? This means the device
current will be 0.89Arms X 5.26 = 4.71Arms.? The input power will be
12VDC (the full source voltage) x 4.71Arms (the effective source
current) = 56.5W.? Effective load on the power supply looks like
12V/0.89A = 13.4 ohms.? Since the output power is 40W, this means
the device dissipation ideally would be 16.5W.? Translated to the
resistive equivalent, this would look like a 63.2Vrms (not a
coincidence the same as the peak output voltage) x 0.89Arms = 56.5W
source through an output impedance of ((Vsource/Voutput) - 1) x 50
ohms = 20.7 ohms.? The actual output impedance of an amplifier is
much more complicated than this, due to the device intrinsic
resistances, transformer inefficiencies and any slump in the power
supply.? If there is any negative feedback around the output stage
(for parasitic suppression or gain flattening), this further reduces
the effective output impedance (note that audio amplifiers use very
heavy negative feedback and have nearly zero output impedance).
If we now output only 10 watts from this same stage, the output
voltage and current are each reduced by half. 10 watts to a 50 ohm
load gives an output voltage of SQR(Pout*Rload) = 22.4Vrms =
31.6Vpeak and output current of SQR(Pout/Rload) = 0.45Arms =
0.63Apeak.? The device current will be 0.45Arms X 5.26 = 2.35Arms.?
The input power will be 12VDC x 2.35Arms = 28.3W.? Note that the
output power went down by a factor of 4 but the input power only by
2 (same voltage, half the current).? Effective load on the power
supply is 12V/0.45A = 26.8 ohms.? Since the output power is 10W,
this means the device dissipation ideally would be 18.3W.?
Translated to the resistive equivalent, this would look like a
63.2Vrms (yes, the same as before - somebody has to drop the voltage
across it) x 0.45Arms = 28.3W source through an output impedance of
91.1 ohms.? Again, the actual effective output impedance may be very
different from this.
However, again, the tuner/antenna system is not intended to match
the amplifier output impedance to look like 50 ohms to the
feedline.? It is to present a 50 ohm resistive load to the
amplifier.
73,
David N1HAC
On 8/3/22 10:06 AM, Ashhar Farhan via
groups.io wrote:
toggle quoted message
Show quoted text
David,
Here is the explanation as I see it.
First, the impedance. It is the ratio of voltage to
current. Let's skip RF and only consider DC, then we will
expand this to DC.?
Ex 1: Consider a 12 supply?that is delivering 40 watts of
power to a resistor across it's terminals. It's current should
be 3.3A, so that 12v x 3.3A = 40 Watts. Now, which also means
that the resistor is 12V/3.3A =? 3.6 ohms. This is also the
case of the full power of sBitx.?
Ex 2: Now, consider that we have decreased the output of
the power supply's current?only such that we are producing? 12
watts of power. The current will now be 1 A (as 12v x 1A = 12
Watts) and the load resistance required will be 12 ohms (12V /
1A). Hence, the load impedance is changed. If you still put a
3.6 ohm resistor, the voltage from the power supply will drop
down and become unregulated and unstable, the power supply is
overloaded.
Now, let's switch to an RF 'power supply', that is, a
transmitter.?
The output impedance of a power amplifier, derived from the
above explanation is given as (Vcc * Vcc)/ (2 * Po). That is,
output impedance of the power amplifier is calculated as
square of power supply voltage divided by double the output
power.
Ex 3: Consider a QRP transmitter like the BITX20 or QRP
labs QCX. The Vcc is 12v and the output power is 5 watts,
hence, the PA output impedance is (12 * 12)/ ( 2 * 5) = 14.4
ohms.?
Ex4: In the above Ex 3, now consider that you have reduced
the power to 1 watt. The Vcc is still 12V, hence, the output
impedance is (12 * 12) / (2 * 1) = 72 ohms.
In case of regular SSB transmitters, they are tuned to
match at the maximum output to protect the transistors from
excessive power remaining in the device at the peak output, it
also makes sense as for CW and other continuous carrier modes
like FT8 and RTTY, the output power doesn't vary but remains
the same as the peak ssb envelope power.
- f??
This is not correct.? The output impedance of the PA
does not change the SWR and resistance/reactance of the
tuner/antenna combination.
What one is really doing is tuning out the reactance of the
antenna and setting the load resistance to the design value
of the amplifier.? A reactive load increases the dissipation
of the PA finals.? Tuning at low power within the voltage
and dissipation limits is safe.
David N1HAC
On 8/3/22 3:44 AM, Ashhar Farhan via
wrote:
Many recommend tuning at a lower power.
This risky as well. That is because at lower power, the
output impedance of the PA will be different. Once you
are tuned at QRP level, increasing the power will result
in a mismatch again!?
- f
Unfortunatel, no. The sbitx has no way
to check the swr (yet).?
Even if it had, as we are dealing
with very high power, fiddling with the tuner for
15-20 seconds with large mismatch will send all
the 40 watts back into the PA, destroying it.
What will work is a resistive
bridge. This will dissipate most of the power in
big resistors until you are tuned up.?
You can paraellel up ten x 470 ohm
resistors of 1 watt to make each of the three legs
of the resistive divider of the swr bridge. A DPDT
switch can bypass it once you are all tuned up.
On Wed, Aug 3,
2022, 12:21 PM Trevor Stone < tstone@...>
wrote:
In the
operating manual I see the following warning:
```
# 1. Connect the Antenna first!
The antenna jack on the back must always be
connected to a properly
matched antenna with an SWR of less than 2 on the
frequencies you intend
to transmit on. This is a recommendation for all
amateur wireless radios
but more specifically the sBitx. The sBitx can put
out upto 50 watts of
power and if the antenna does not match, it can
damage the power
amplifier transistors instantaneously.
```
Does the sBitx have the ability to tune or check
the SWR without
damaging itself, or does one need to use an
antenna analyzer before
using the radio?
I ask because most of my operation is portable, so
my SWR changes every
time I set up my station.? SWR can be high even
for an antenna of the
right length if it's deployed in a compromised
position or if I made an
error during setup (like last month when I forgot
to attach
counterpoises to an end-fed antenna :-)
Thanks,
Trevor KF0FTJ
--
=-=-=-= Trevor Stone -=- [Flwyd] -=- <tstone @
>
=-=-=-=
Computer science, eclectic philosophy, games,
wits, esoterics, odd hats
?
? ? ? ? ?Thou brazen boil-brained malt-worm!
{embrace society}? ? ? ? ? ? ? ? ? ? ? ? ?
POLAROID does it in seconds.
Calvin: The world is a complicated place, Hobbes.?
Hobbes: Whenever it
seems that way, I take a nap in a tree and wait
for dinner.
|
Re: Farhan's Analog Again The Daylight Radio
The plans are clear to me except for T1 and T2. How are the trifiliar transformers wound? How many turns on what size toroid? Are 2 and 6 really unconnected?
--
? 73
??? Bob? KD8CGH
|
Re: sBitx, customs and management fees
Ken,
In Spain, then VAT tax is 21%. 270$ x 0.21 is aprox. 53€.
DHL management cost could avoid it, but I would have to go to Madrid, do the management, lose a few hours, etc. It is the price of comfort.
The online seller should, or could, include VAT in the price (this is how AliExpress does), but that's a minor issue.
Public services must be paid.
¸é²¹³¾¨®²Ô?
|
it is possible that you might want to switch the audio output to a couple of different things..
check this out...
vince N2AIE
|
Re: sBitx antenna-first warning
Most SWR meters (for the HF frequencies) don't measure SWR. They just measure how far off the antenna/coax load is from 50 ohms (reactive and resistive).
The only reason they are fixated on 50 ohms is nearly everyone uses 50 ohm coax, and it is a good idea to try to match the 50 ohm coax for minimum loss in the coax. However, the SWR measurement is usually made at the transmitter end of the cable, so the SWR across the length of the coax cable could be high. You could just be at a lucky multiple of a 1/4 wavelength that could make the impedance of the antenna/coax system (where you stuck the SWR meter) look close to 50 ohms.?
I agree, the reactance part of the load is what kills the finals. There may be, indeed, "reflected" waves. But, the reflected waves don't somehow have electrons managing to fight their way in the opposite direction to attack, pillage and lay waste to the RF finals. The "mismatch" can be reactive (look too much like an inductive or capacitive load) and cause problems with power dissipation or excessive voltage when the finals try to drive that load.?
At HF the only way to measure the actual SWR would be to do what the old timers did. Actually run a measuring device down the length of the cable (if long enough) and records the maximin and minimum readings.?
Tom, wb6b
toggle quoted message
Show quoted text
On Wed, Aug 3, 2022 at 07:11 AM, Jerry Gaffke wrote:
There is room for doubt here.
An SWR meter assumes the transmitter wants to see a 50 ohm resistive load.
A uBitx/sBitx might work a bit better into a load that is somewhat different than assumed.
Jerry,? KE7ER
Hide quoted text
?
On Wed, Aug 3, 2022 at 06:20 AM, David McGaw wrote:
This is not correct.? The output impedance of the PA does not change the SWR and resistance/reactance of the tuner/antenna combination.
What one is really doing is tuning out the reactance of the antenna and setting the load resistance to the design value of the amplifier.? A reactive load increases the dissipation of the PA finals.? Tuning at low power within the voltage and dissipation limits is safe.
David N1HAC
?
|
Re: sBitx, customs and management fees
toggle quoted message
Show quoted text
On Aug 5, 2022, at 11:36, Ian Reeve <ian.radioworkshop@...> wrote:
?
As I understand it is for the UK calculated at VAT on cost and postage plus and admin fee for the courier company.The admin fee is to cover collection of and passing to hmrc with appropriate paperwork.If the item is described and marked on the
customs declaration as a kit, I thought it was VAT exempt although there is still a admin fee for the customs declaration.These charges are levied by the customs at point of entry to your country so there is plenty of scope for miscalculation.
Get
I got my sbitx today, additional 95 euro for Irish customs. Welcome to the EU.
On Fri 5 Aug 2022 at 16:42, Ken N2VIP < ken@...> wrote:
Ouch! As a US Ham I'm curious how the €53 VAT is calculated, since the stated value is, what, about €250-300?
Sadly, the €43 for "customs management" is likely a fixed paperwork fee no matter the value of the shipment.
I wonder if VAT could be pre-paid to avoid the "customs management" fee? The VAT itself is (apparently) owed & should be paid, but maybe the additional fee can be avoided?
Anyway, just curious,
Ken, N2VIP
?
Hello,
I just received my sBitx, Basic Kit. It has been accompanied by an additional payment of €53 VAT for the Treasury and €43 for DHL for customs management.
?
So the radio has been a little more expensive than expected but I am sure it will be worth the extra cost and I will enjoy it a lot.
?
Notice for European Union buyers!
?
Ramon EA4GZI
|
Re: sBitx, customs and management fees
As I understand it is for the UK calculated at VAT on cost and postage plus and admin fee for the courier company.The admin fee is to cover collection of and passing to hmrc with appropriate paperwork.If the item is described and marked on the
customs declaration as a kit, I thought it was VAT exempt although there is still a admin fee for the customs declaration.These charges are levied by the customs at point of entry to your country so there is plenty of scope for miscalculation.
Get
toggle quoted message
Show quoted text
I got my sbitx today, additional 95 euro for Irish customs. Welcome to the EU.
On Fri 5 Aug 2022 at 16:42, Ken N2VIP < ken@...> wrote:
Ouch! As a US Ham I'm curious how the €53 VAT is calculated, since the stated value is, what, about €250-300?
Sadly, the €43 for "customs management" is likely a fixed paperwork fee no matter the value of the shipment.
I wonder if VAT could be pre-paid to avoid the "customs management" fee? The VAT itself is (apparently) owed & should be paid, but maybe the additional fee can be avoided?
Anyway, just curious,
Ken, N2VIP
?
Hello,
I just received my sBitx, Basic Kit. It has been accompanied by an additional payment of €53 VAT for the Treasury and €43 for DHL for customs management.
?
So the radio has been a little more expensive than expected but I am sure it will be worth the extra cost and I will enjoy it a lot.
?
Notice for European Union buyers!
?
Ramon EA4GZI
|
Re: sBitx, customs and management fees
I got my sbitx today, additional 95 euro for Irish customs. Welcome to the EU.
On Fri 5 Aug 2022 at 16:42, Ken N2VIP < ken@...> wrote: Ouch! As a US Ham I'm curious how the €53 VAT is calculated, since the stated value is, what, about €250-300?
Sadly, the €43 for "customs management" is likely a fixed paperwork fee no matter the value of the shipment.
I wonder if VAT could be pre-paid to avoid the "customs management" fee? The VAT itself is (apparently) owed & should be paid, but maybe the additional fee can be avoided?
Anyway, just curious, Ken, N2VIP ? Hello,
I just received my sBitx, Basic Kit. It has been accompanied by an additional payment of €53 VAT for the Treasury and €43 for DHL for customs management.
?
So the radio has been a little more expensive than expected but I am sure it will be worth the extra cost and I will enjoy it a lot.
?
Notice for European Union buyers!
?
Ramon EA4GZI
|
MadRadioModder
Vince N2AIE
David McGaw
Bob Benedict, KD8CGH