Re: IRF510 amplifier failures
Interesting comments thus far regarding IRF510 failures.? - Power supply current limiting (2.5 to 3A) seems to work.
- Bias voltage shutdown on high current (3A) seems to work.
- Driver impedance to IRF510 gate should be quite "stiff".? Use a 50 ohm pad.
- Use small resistance (4.7 ohms) in series with each IRF510 gate lead.
- Keep IRF510 leads short.
- Impedance presented to the IRF510 drain should be 12.5 ohms.
RF output transformer should be 1:2 windings for 1:4 impedance transition.
Binocular core may work better...?
- Avoid the problem by using some other MOSFET.
- Use plastic fuses at 3A for self-healing action.
- Fuse rig power at 2 to 3A to avoid IRF510 failures.
Some of the on-line information also mentioned low level background noise being generated by MOSFET RF PA stages that remain powered during receive mode.? Possible solution here might be to add a MOSFET switch in the DC power lead going to the IRF510s so this power could be shut off during receive.
All good info.? Now how to keep within the original BITX objective of making rigs
that can be afforded by those with limited spare cash and still make them reliable
and inexpensive.? This solution(s) has potential for modification of existing
transceivers, and for future redesign of the similar units.? It also has application
for designing and adding homebuilt RF amplifiers for your BITX rig.
Arv? K7HKL
_._
On Fri, Jan 26, 2018 at 10:32 AM, Jerry Gaffke via Groups.Io <jgaffke@...> wrote: The RD15HVF1's should be operated at not much more than 12v.
At 12v, the IRF510's would survive just fine with no antenna connected.
That's an infinite VSWR.
So not obvious that this is a solution to blown FET's.
Though I do think the the Ids curves go up more slowly as Vgs increases on the RD15HF1's,
which makes RV2,RV3 not so touchy.
And the RD15HF1's might be easier to drive at 30mhz.
If you do swap them in, let us know how much power you get at 30mhz.
Jerry, KE7ER
On Fri, Jan 26, 2018 at 03:54 am, KD8CGH wrote:
Wouldn't it be better to change to a RD15HVF1 for high VSWR
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I just received 3 of the MCUFriend 3.5" TFT displays purchased from "accecity2006" on eBay. One of the 3 worked correctly; one was cracked and another one was not displaying text correctly.
--
John - WA2FZW
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I bought two 1800s, they would not fit my ubitx pcb at the bottom of the case by a fraction of an inch because of the orientation of the raduino and heat sinks on the short axis of the card, they must point to the sides. Leaving the long axis of the card to fit front to back in the case.?
Instead, I selected the Seahorse SE300, more expensive, but also has screw bosses molded into both the case and lid which means easily hanging the PCB from stand offs instead of puncturing the case.?
John
On Jan 26, 2018 10:48 AM, "John P" < j.m.price@...> wrote: This if the January flyer, so it doesn't show the sale price.
--
John - WA2FZW
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Re: Something has been blown
It is very frustrating. I don¡¯t have any watt showing up in my power meter even in the 2w scale
how do I know I blew the fets again??
When ptt i get 0,5amp and adjustin It is too sensitive. Even one time it got crazy with a very loud beep coming through the speaker an i had to turn it off
when i whistle no extra power is drained
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Is anyone up for maintaining a database of Bitx by serial no. to include purchaser, ordering, shipping and delivery dates, and info about subsequent issues and modifications?
For info, mine was ordered on 16-Dec (for shipping to UK via Indian P.O.), acknowledged by email from HFSignals on 31-Dec, and a couple of days ago (following my enquiry to HFSignals) I was informed it would ship in 2-3
days. No advice from PayPal as yet.
Chris
G3SQU
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I sent a mail to hfsignals they said the next round is in about 2 weeks. I also ordered on the 23rd.
--
David
?N8DAH
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Re: IRF510 amplifier failures
?
On Friday, January 26, 2018 1:01 PM, James Lawrie <lawriejk@...> wrote:
On same site I found these, made for 30 MHz? RD16HHF1. Sooo I bought 10 of them, plan to try in Bix40 first. Data sheet even shows a reference amp design, and they are 12 volt like the other one. If it works I¡¯ll let everyone know.
On Jan 26, 2018, at 11:32, Jerry Gaffke via Groups.Io < jgaffke@...> wrote: The RD15HVF1's should be operated at not much more than 12v. At 12v, the IRF510's would survive just fine with no antenna connected. That's an infinite VSWR. So not obvious that this is a solution to blown FET's. Though I do think the the Ids curves go up more slowly as Vgs increases on the RD15HF1's, which makes RV2,RV3 not so touchy. And the RD15HF1's might be easier to drive at 30mhz. If you do swap them in, let us know how much power you get at 30mhz. Jerry, KE7ER On Fri, Jan 26, 2018 at 03:54 am, KD8CGH wrote:
Wouldn't it be better to change to a RD15HVF1 for high VSWR
|
I sent a mail to hfsignals they said the next round is in about 2 weeks. I also ordered on the 23rd. -- David
?N8DAH
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Re: uBitX - Replacement microphone
Thanjk you Michael
Let me check your suggestion.
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Re: IRF510 amplifier failures
On same site I found these, made for 30 MHz? RD16HHF1. Sooo I bought 10 of them, plan to try in Bix40 first. Data sheet even shows a reference amp design, and they are 12 volt like the other one. If it works I¡¯ll let everyone know.
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On Jan 26, 2018, at 11:32, Jerry Gaffke via Groups.Io < jgaffke@...> wrote: The RD15HVF1's should be operated at not much more than 12v. At 12v, the IRF510's would survive just fine with no antenna connected. That's an infinite VSWR. So not obvious that this is a solution to blown FET's. Though I do think the the Ids curves go up more slowly as Vgs increases on the RD15HF1's, which makes RV2,RV3 not so touchy. And the RD15HF1's might be easier to drive at 30mhz. If you do swap them in, let us know how much power you get at 30mhz. Jerry, KE7ER On Fri, Jan 26, 2018 at 03:54 am, KD8CGH wrote:
Wouldn't it be better to change to a RD15HVF1 for high VSWR
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Re: BITX QSO Afternoon/Night, Sunday, January 28, 3PM/7PM Local Time, 7277 kHz in North America, 7177 kHz elsewhere
good call Ed. The GM (General Motors Employee/retirees) net operates on 7.277.5 - should NOT be a problem but can be used to check propagation during the week.? ? ? ? ? ? ? ? ? ? GM HF Net Mon thru Sat 1:00pm (HF 7,277.5 KHz).?
I think the mod to RLS 2 will help with the heterodyne we hear AM broadcasters in our 40M ham band in North America. I don't have the new uBITX built yet but I'm hoping it's not a problem too. Using an external DSP and/or notch filter does help a lot.
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Re: remote display was Apache Case on Sale
Jack and All,
attached 2 pix of remote display. Note that I used DuPont wires
that came as a flat-group, not the helter-skelter loose wires.
Probably helps reduce noise to some degree.
The ubitx is in an old Heathkit Frequency counter cabinet. When
fully assembled, the cabinet looks good, and has
plenty of room for add-ons, and has good cooling louvers.
I will install a fan just behind the finals. The fan will be
pulling air away from the finals, not blowing onto them.
Downside of using this case: the 12 inch Nano USB extension cable
will not reach the back panel; had to bring
it out through the front.
Rod KM6SN
On 01/26/2018 08:38 AM, Jack Purdum via
Groups.Io wrote:
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That's good
news! I'm thinking of using ribbon cable and grounding every
other wire.
Jack, W8TEE
From:
Rod Self <km6sn@...>
To:
[email protected]
Sent:
Friday, January 26, 2018 11:35 AM
Subject:
Re: [BITX20] remote display was Apache Case on Sale
Jack,
I
used 6 inch Dupont wires with no shield-no
apparent problems.
Rod
KM6SN
On
01/26/2018 06:43 AM, Jack Purdum via Groups.Io
wrote:
I
think there are a number of people who have
moved the display away from the main board to
give them some flexibility in terms of display
placement. Evidently, some shielding is
needed, but I think I recall someone simply
wrapping the cable in foil mitigated the
problem. I'd like to hear from anyone who has
moved the display and what their experience
is.
Jack,
W8TEE
I
love the idea of a "portable field
radio" with all the controls on the
top in a watertight case like this.
?I'm thinking of modeling it after a
bitX40 build I saw here, and this
case looks like the perfect size!
Is there any reason I couldn't do
that with the uBitx? ?It looks like
the LCD plugs directly into the
board, but would it give me noise
issues if I used a short length of
ribbon cable to move the LCD to face
upwards?
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See my signature below for a link to join the Discord. For all intents and purposes, it's the same as Slack.?
3-5 people are usually active, 51 people have logged in at one point so far.
Cheers!
--
David K4DBZ
Unofficial bitx chatroom:?https://discord.gg/CrHvWFc
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Re: IRF510 amplifier failures
The RD15HVF1's should be operated at not much more than 12v.
At 12v, the IRF510's would survive just fine with no antenna connected.
That's an infinite VSWR.
So not obvious that this is a solution to blown FET's.
Though I do think the the Ids curves go up more slowly as Vgs increases on the RD15HF1's,
which makes RV2,RV3 not so touchy.
And the RD15HF1's might be easier to drive at 30mhz.
If you do swap them in, let us know how much power you get at 30mhz.
Jerry, KE7ER
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On Fri, Jan 26, 2018 at 03:54 am, KD8CGH wrote:
Wouldn't it be better to change to a RD15HVF1 for high VSWR
|
Hi Manoel, My group has had a lot of fun working on this project.? With winter upon us (lots of snow), and living up in the mountains in the northwest U.S., getting together for classes is a challenge.? We have had two classes to date and the group has completed assembling and testing the audio amps board, the 3 bidirectional amps,? the low pass filter, and installed all of the SIP sockets on the motherboard.? Our next class is scheduled for 17 Feb and the plan for this session is to complete and test the crystal filter, the mixer, the product detector, and the VFO.? We'll save the PA module for last along with building the external VFO (Si5351).? I did find that on the analog VFO it was almost impossible to eliminate the drifting so I decided not to install those components since we will be using an external VFO anyway. The only fault I found with any of the boards was that you didn't include pads to connect M1/M2 from the relay on the PA module to the audio amp module.? I worked around this by soldering two wires with a header to the relay contact pads on the PA module.? The header plugs in to pins on the motherboard with traces running to the audio amp module. Again, it was terrific of you to share your work on Hackaday and the experience that my guys are getting from building this transceiver is invaluable.? If you will email me direct I would be pleased to mail you one of the motherboards that I designed for the project as my way of saying thank you. --73-- Mike? --? W0MNE 
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Re: uBitX - Replacement microphone
Sajid :?
I am using a Koss CS-100 Computer headset on my BITX40 with excellent results. These cost less than $US20.?
I have tried a couple of other inexpensive Computer Headsets and have found that with some the microphone is?
not sensitive enough for use with the BITX (i.e. output is very low).?
?I have also used a more expensive Yahama CM-500 that works very well.
The nice thing about computer headsets is that the non-USB models normally use 3.5mm stereo plugs for both Headphone and?
mic connections, making it easy to get jacks and to drill appropriate sized holes in your enclosure.
Cheers
Michael VE3WMB?
P.S. For PTT I am using large momentary switch mounted in a plastic pill box with a 3.5mm stereo jack on the bottom. This allows me to?
use a normal 3.5mm audio cable to connect it to the rig.?
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Re: Second batch of uBITX shipping?
#ubitx
I ordered on Dec 14 and have not heard from them since...I did hear rumor shortly after I ordered that it wouldnt ship until the end of January..That day is fast approaching and still no word. Maybe we need to bring this project onto US soil..
Brian K9WIS
---- mikael.madsen@... wrote:
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Someone posted that order date 14th december had been shipped but that was some days ago.
Anyone with a later order date later than 14th been informed of shiping yet?
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One of us set up a discord group.? Many joined, few are on.
/g/BITX20/topic/7355353#35099
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I was thinking the same thing, something a bit more interactive than an email list.? I'll sign up.
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? ? for any who wish to join and interact ¡ ? Sent from for Windows 10 ?
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From: Richard E NeeseSent: Friday, January 26, 2018 12:05 PM To: [email protected]Subject: [BITX20] Slack Client group ? Might I suggest we get a slack group going where we can talk real time and interact. living by email is a bit hard as it seems to pile up fast you can make a group with channels like bitx20 bitx40 ubitx so people can join multi rooms and also beable to do? more realtime discussion and interaction ?
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Re: Something has been blown
I'd leave the round blue trimmer where it was set at the factory.
It adjusts how much transmit signal power is sent on to the IRF510's.
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On Fri, Jan 26, 2018 at 08:23 am, C¨¦sar EA3IAV wrote:
what is that round blue trimmer for?
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N8DAH
James Lawrie
Arvo W0VRA
