Re: IRF510 amplifier failures
It would seem to me that this type of operation is actually AM modulation of final. When you limit the current flow in an FET that is very similar to plate modulation in a vacuum tube. It certainly can't be good for the linearity of the amplifier since the operational curve would no longer be linear but, instead, flat-topped at some value. Why not just fuse the power lead? It would tell you immediately that you have a problem. tim ab0wr On Sat, 27 Jan 2018 12:13:49 -0800 "Arv Evans" <arvid.evans@...> wrote: Hello
Still thinking about IRF510 failures and ways to avoid making
smoke.....
It seems that there may be two ways to limit current in BITX RF PA
stages that use the IRF510 device.? First would be to incorporate a
current limiter in the positive voltage supply to the RF PA stage.
Second might be to use current sensing in the RF PA supply line to
cause a voltage drop in the MOSFET bias line(s).?
In the first instance it should be possible to use another IRF510 or
preferably a higher power, MOSFET as a control that limits voltage to
the RF PA section if the current exceeds a preset value (usually this
would be 2.0 to 3.0 amperes).?
This circuit has not been built or tested by me (too cold in Idaho
hamshack in winter). The MOSFET could be an IRF840, or similar.
Option-B? potentially solves another problem, that of low level noise
from powered RF PA stage during receive mode.?
In the second instance we could get by with smaller control devices
if we used current sensing in the RF PA power line to turn off bias
to the IRF510 device(s).?
This bias control circuit used by AC2CZ in his 50 watt IRF510 linear
( ).? You could probably
do this using 2N3906 transistors.? I like the fact that it includes a
warning light/LED.
Arv? K7HKL
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Re: TEST MESSAGE...Please Ignore
I'm a bit busy right now. Can I ignore it later? :)
On Sun, Jan 28, 2018 at 7:36 PM, Arv Evans <arvid.evans@...> wrote: This is a test message by a moderator for testing addition of an informational footer to email replies.
Arv? K7HKL
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Re: uBITX woes, feeling disheartened.
#ubitx
They are standard
relays, look on eBay.
73's
Mike, WA6ISP
On 1/28/2018 7:58 PM, Bob McMillan
wrote:
I had trouble with k3 relay not
switching back to receive. Couldn’t find a replacement
Luckily re-solder seemed to solve the problem. I would like to
find a replacement just in case.
Bob
W5rkm
--
Mike Hagen, WA6ISP
10917 Bryant Street
Yucaipa, Ca. 92399
(909) 918-0058
PayPal ID "MotDog@..."
Mike@...
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Re: I did it again.. i plugged the arduino pins on reverse
I haven’t measured it ... but machine pin headers may work?? They are pretty low profile.
M
On Mon, 29 Jan 2018 at 5:03 PM, John Backo < jabac@...> wrote: True. Raj.
But it is easy enough to cable the display.
This has been discussed before on the forum.
It means a little bit different way of mounting the rig.
And the benefit of a removable nano outweighs
the inconvenience, I think.
john
AD5YE
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Re: I did it again.. i plugged the arduino pins on reverse
True. Raj.
But it is easy enough to cable the display.
This has been discussed before on the forum.
It means a little bit different way of mounting the rig.
And the benefit of a removable nano outweighs
the inconvenience, I think.
john
AD5YE
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Re: uBITX woes, feeling disheartened.
#ubitx
I had trouble with k3 relay not switching back to receive. Couldn’t find a replacement
Luckily re-solder seemed to solve the problem. I would like to find a replacement just in case.
Bob
W5rkm
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All kits are gone. -- David
?N8DAH
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Please save an assembled board for me, too. ? I knowmshipping to Australiamwill robably be extra hihi.
Norm. Vk5gi
The Vineyard
28/170 Main Road
McLaren Vale. ? SA. ? ? ?5171
Australia
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Re: I did it again.. i plugged the arduino pins on reverse
Gordon & Cesar,
The display will not fit into socket if the Nano is mounted on sockets!
Raj
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At 29/01/2018, you wrote: Yes, it is, Cesar, and now you might want to solder in female headers on those open sockets and then you can just PLUG IN a nano rather than soldering in the next one......sorry for the troubles you're having.....we've all made those kinds of mistakes.....
gordon
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Re: uBitx audio potentiometer question.
50K audio taper will work and you might fine CW side tone loud.
Raj
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At 28/01/2018, you wrote: I have a 50 k audio taper pot, will that work okay for the uBitx?
I also have a 10 k LINEAR taper pot, will that work? Which is preferred?
I am trying to work around the shaft diameter problem ...
thanks,
Paul K0ZYV
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Re: I did it again.. i plugged the arduino pins on reverse
Cesar:
It is likely that you blew out the nano.
The most sensitive part of the nano (and most of the arduino clones)
is the USB interface (CH340 or CP2102 or ATMega32U). IF that goes,
even though the ATMega chip is good, it will not respond to the IDE.
You can check the voltages and regulators easily enough. Look
for the Vin, 5v, and 3.3v pins. If they are all ok, then the basic board is
ok and the ATMega chip MAY be ok...but maybe not, as one or more of the
port pins may be bad.
All in all, if the display disappears, and one cannot load a blink program,
get a new nano. Make the installation removable by installing female pins
on the board and male pins on the nano.
Note that if you still have 3.3v, it is likely that the Si5351 is good. IF not,
that may be blown as well...but it usually takes quite a bit to do that.
The usual suspects are the USB chip first, the regulators or ATMega chip
second, and the Si5351 third. Most of the "diagnosois" can be achieved with
a good schematic and DVM. However, only a reload of the program will
tell you about the state of the ports.
You are probably wise to replace the nano board.
john
AD5E
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Check out these on eBay cost me a just under ?2 each I got 3 of them just not tested yet chris
On 28 Jan 2018 22:27, "at91r40008" < yvon@...> wrote: I tried every single mike that I have with no success. That is until I tried the mike that
came with my LNR LD-5. I finally had power out in SSB. I did order two more from
LNR and they came in yesterday. They are only $20 each. This afternoon I made my
first SSB QSO with the uBitx?with W7DGZ in Washington state. I am in south California.
The conditions where not?good with a lot of QSB. Still the same excitement on the first.
QSO with a new radio?as when I was licensed in 1966.
Very quite receiver I love it.
--
73, Yvon NU6I
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Re: TEST MESSAGE...Please Ignore
Maybe include the Discord chat room link? (see my signature). There are still a few of us in here regularly.
--
David K4DBZ
Unofficial bitx chatroom:?https://discord.gg/CrHvWFc
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All kits are spoken for at this time -- David
?N8DAH
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David, I would like an assembled board if possible. PayPal OK? 73, Gordon Beattie, W2TTT 201.314.6964
On Sunday, January 28, 2018 5:58 AM, N8DAH <Dherron@...> wrote:
I have 10 kits ready to go with another 10 for kits or pre-built.
This was posted on DuWayne KV4QB's site found
Thank you DuWayne for the use of the board layout and files!
All kits will come with:
PCB x 1
Parts placement layout x 1
2N3904 x 1
2N7000 x 1
47uf x 2
1N4148 x 1
100R x 3
100k x 3
10k x 1 this is extra for the user to play with attack or input values.
2k2 x 1
.1uf x 2 unmarked tan
If you lose anything let me know I will send you a replacement.
This is the 3rd run of the boards, many users here have this AGC already in use myself included. It was setup for the Bitx40 but I have not tested it with the Ubitx yet (should work).
?
Cost and options:
#1 - Kits 13$ shipped
#2 - Pre-built OT service 15$ shipped and tested
Please contact me before you send any money the last two times I have offered just the boards they sold out in under 24 hours.
As before I am not yet a store so please have patience and 1st come 1st serve. If all goes well I have plans to roll the income from this run into purchasing Eagle and making a new adjustable AGC with all surface mount, surface mount led zero beat and more!
Contact me directly for more information or orders: dherron at live dot com
I will send you a confirmation and direct you to my paypal for payment.
--
David
?N8DAH
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Re: TEST MESSAGE...Please Ignore
I am reporting successfully ignoring this message.
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Re: BITX QSO Afternoon/Night, Sunday, January 28, 3PM/7PM Local Time, 7277 kHz in North America, 7177 kHz elsewhere
moving up 7.278 -- David
?N8DAH
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Re: BITX QSO Afternoon/Night, Sunday, January 28, 3PM/7PM Local Time, 7277 kHz in North America, 7177 kHz elsewhere
Worked N4DR gave him a 33 but the band dropped before I could get a report back
Heard one other station call me but noise it just too much.
Still on 7.277
--
David
?N8DAH
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Re: Firmware for using rotary encoder
Look for the Bitx40 Amunters sketch on Does LSB, USB , CW. Needs some hardware wiring, but not much.
KC9SGV
Sent from my iPad
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On Jan 28, 2018, at 3:57 PM, Fred WA0GMH < flderoos47@...> wrote: I just finished mounting my Bitx40 in a box and wiring the controls.? It works great and is much more sensitive than I expected.? I still have to wire up a microphone and see how it transmits.? My plan is to replace the band pass filter and low pass filter so that I can use the radio on 630 M to operate JT-9.? It would be nice to use an encoder, rather than the pot for tuning and I also need to switch from LSB to USB.? I have a little experience with programming the Arduino, but just a little!? So, is there a version of the firmware that includes using an encoder for tuning and allows switching between LSB and USB?? From what I've seen, the firmware is pretty well commented, so I'm hoping that finding where to set the BFO frequency and set the range of the VFO frequency will be obvious.
Fred WA0GMH
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Mark Phillips
Bob McMillan
N8DAH
Raj vu2zap
Arvo W0VRA