? ? ? ? ? ? ?Thank you all for the information, I'm going to buy a PA kit but rest assured, the IRF510 with the 20 VDC in the drain should provide that power? Can I do this? ? ? ?Jorge PY2PVT _._
Jorge:
Note that you cannot directly substitute a IRF530 for a IRF510.
That is because the input gate capacitance of the 510 is ~180 pF.
and the gate capacitance of the 530 is ~620 pF. That means the input impedance is
considerably different and needs compensation. There is also a difference in
the drain capacitance which will affect the LPF match.
If these are compensated for, with 20v on the drain, the Pk-Pk AC output voltage can be about
36-40v. (The maximum wattage handling ability of the 530 is about 85W.) Note that the heat sink
must be considerably increased in size.
If you want to increase the wattage that much, you should probably opt for a drain voltage of ~36v.
With a suitable matching network and heat sink, that should allow a Pk-Pk voltage of about 70v.
Note that heat is still the biggest enemy and consideration, as it is in any MOSFET PA.
If you are opting for that much power, you probably would be better off designing or building a dual
IRF530 PA. The BITX3B PA would have to be considerably modified, even if the drain voltage were kept low.
You could probably get away with the current design (modified for impedance) with a IRF520, but
probably not a IRF530.
Check the internet; there are many designs out there.
john
AD5YE
-- ? 73 de Jorge PY2PVT
? Campinas SP
? GG67MD
|
Re: Bitx40 vs the antenna beast
Thanks for all the responses. I was actually Fred's guidance that did the trick. I had the antenna close to 1:1 in about 15 minutes before herself decided we needed to do other things. I'll get it tuned today and hook the radio up to it and see where I'm at then. Thanks for all the help everybody!
73, Richard W2KAP 
On 29 Apr 2017, at 00:02, Dr Fred Hambrecht < AAR4MI@...> wrote:
Use the MFJ to determine where the antenna is resonant. If the frequency is below 7.285 decrease the ?amount of coil and recheck. Conversely if it is resonate
above 7.286 you will have to add coil.
?
v/r
Fred W4JLE
?
|
Just a thought are there any ?IGBT devices that will work at 7mhz - the switching losses would be lower.?
Sent from my iPhone
toggle quoted message
Show quoted text
On 29 Apr 2017, at 12:08, Richard Andrew Knack via Groups.Io < ihc73scout2@...> wrote: If it is the same 45 watt amplifier kit I bought a couple years ago, be aware that the INPUT of the amplifier needs to be EXTREMELY small - as in, milliwatts - or it will blow. Check the specifications, before you decide! I ended up buying a ready-made MX-P50M amplifier that will take 5 watts in and put out 45 watts, to use with my QRP equipment.
Rich KC8MWG
On Friday, April 28, 2017 11:05 PM, Mvs Sarma <mvssarma@...> wrote:
There is a 45w amp kit sold rather cheap on ebay and aliexpress both.
|
If it is the same 45 watt amplifier kit I bought a couple years ago, be aware that the INPUT of the amplifier needs to be EXTREMELY small - as in, milliwatts - or it will blow. Check the specifications, before you decide! I ended up buying a ready-made MX-P50M amplifier that will take 5 watts in and put out 45 watts, to use with my QRP equipment.
Rich KC8MWG
On Friday, April 28, 2017 11:05 PM, Mvs Sarma <mvssarma@...> wrote:
There is a 45w amp kit sold rather cheap on ebay and aliexpress both.
On Sat, Apr 29, 2017 at 6:40 AM, John Backo via Groups.Io <iam74@...> wrote: Jorge:
Note that you cannot directly substitute a IRF530 for a IRF510.
That is because the input gate capacitance of the 510 is ~180 pF.
and the gate capacitance of the 530 is ~620 pF. That means the input impedance is
considerably different and needs compensation. There is also a difference in
the drain capacitance which will affect the LPF match.
If these are compensated for, with 20v on the drain, the Pk-Pk AC output voltage can be about
36-40v. (The maximum wattage handling ability of the 530 is about 85W.) Note that the heat sink
must be considerably increased in size.
If you want to increase the wattage that much, you should probably opt for a drain voltage of ~36v.
With a suitable matching network and heat sink, that should allow a Pk-Pk voltage of about 70v.
Note that heat is still the biggest enemy and consideration, as it is in any MOSFET PA.
If you are opting for that much power, you probably would be better off designing or building a dual
IRF530 PA. The BITX3B PA would have to be considerably modified, even if the drain voltage were kept low.
You could probably get away with the current design (modified for impedance) with a IRF520, but
probably not a IRF530.
Check the internet; there are many designs out there.
john
AD5YE
|
Re: Bitx40 vs the antenna beast
If static is the issue, go outside to eg a park. Tuning the antenna only will be important when transmitting.
Find local hams to support getting the receive part working.?
7.285 is good enough to make the bitx40 receive. Go outside to loose the static first.
Ron - PA3FAT
Sent from my iPhone
On 29 Apr 2017, at 00:02, Dr Fred Hambrecht < AAR4MI@...> wrote:
toggle quoted message
Show quoted text
Use the MFJ to determine where the antenna is resonant. If the frequency is below 7.285 decrease the ?amount of coil and recheck. Conversely if it is resonate
above 7.286 you will have to add coil.
?
v/r
Fred W4JLE
?
From:
[email protected] [mailto:[email protected]]
On Behalf Of richard kappler
Sent: Friday, April 28, 2017 2:24 PM
To: [email protected]
Subject: [BITX20] Bitx40 vs the antenna beast
?
So I'm a new ham (General), as I've said before, and aside from a VHF/UHF HT, the BitX is my first (and presently only) radio. I'm in an apartment, so antenna choices are severely limited. I am currently running my BitX through a MFJ-1622,
which is tapped coil 1/4 wave apartment antenna with a 5 foot whip and a counterpoise. ?(? ).
I've NEVER been able to hear anything but static on my BitX40, and have done much troubleshooting, finding nothing amiss thus far (on the second one anyway, the first one I built is another story for another day). I took a wafg and figured
it to be the antenna, ordered the parts for Jack's antenna analyzer, most of which still aren't here. Impatient as I am, I've sprung for an MFJ-259C antenna analyzer, which arrived about an hour ago, and sure as shootin', my antenna appears to be VERY out
of whack.impedance is about 90 ohms, SWR up at 13.5 at freq 7.285.
And now the question: Is this most likely the reason I've been able to hear nothing and no one has been able to hear me?
Then I, of course, have to go OT a bit: Any suggestions as to how to adjust this antenna to something reasonable? Near as I can figure, it has three mechanical adjustments: placement of tap on coil, whip length, counterpoise length.
I will, of course, spend the weekend adjusting everything, one thing at a time, small adjustments, until I figure it out, but if anyone has the antenna knowledge to give me a little guidance, it would sure save some time.
If it's not the antenna, you'll be hearing from me. I've been trying to get on HF for about 2 months now. I've got me an itch that demands scratching!
--
In any given circuit, the most expensive part will always sacrifice itself to protect the fuse.
|
Re: Too Much Information?
We must experiment with the sub group feature.
toggle quoted message
Show quoted text
At 29-04-2017, you wrote: Messages are all the same URL except the final incrementing integer, will be trivial to create a script to grab them one by one. I'm happy enough with the current organization of the group. If somebody wants something different, they can go off and create (and administer) it.
|
Re: Too Much Information?
Messages are all the same URL except the final incrementing integer, will be trivial to create a script to grab them one by one. ?I'm happy enough with the current organization of the group. ?If somebody wants something different, they can go off and create (and administer) it.
I previously wrote:
Would it be possible to do a onetime download of all messages thus far and store it somewhere that I can access it? ?Then I'll turn on daily digests from here on out so I can store them locally as email. ?
|
Re: R15 and ADE-1 mixer getting very hot
Sarma,
Insulation breakdown is highly unlikely. William has replaced them and all can't be having the same problem.
When the problem is found you will see how simple it was! this is my experience from many decades.
toggle quoted message
Show quoted text
At 28-04-2017, you wrote: raj jee,
? There is no heat without ade-1 in place even if the pins 1and 6 are connected with a wire to maintain continuity.
?
Thus it is clear that the trafo inside the mixer covering pins 1&6 is f\getting breakdown (short under real voltage application) to the secondary? and that has middle ground.
Perhaps it would be easy to check placing ade-1 on board and isolating pins 4&6? from ground. later one could connect one by one? pins 4 and 6.
It would show up?
? I finally suppose a case of insulation break down, in real working condition.
regards
? sarma
? vu3zmv
|
|
|
There is a 45w amp kit sold rather cheap on ebay and aliexpress both.
On Sat, Apr 29, 2017 at 6:40 AM, John Backo via Groups.Io <iam74@...> wrote: Jorge:
Note that you cannot directly substitute a IRF530 for a IRF510.
That is because the input gate capacitance of the 510 is ~180 pF.
and the gate capacitance of the 530 is ~620 pF. That means the input impedance is
considerably different and needs compensation. There is also a difference in
the drain capacitance which will affect the LPF match.
If these are compensated for, with 20v on the drain, the Pk-Pk AC output voltage can be about
36-40v. (The maximum wattage handling ability of the 530 is about 85W.) Note that the heat sink
must be considerably increased in size.
If you want to increase the wattage that much, you should probably opt for a drain voltage of ~36v.
With a suitable matching network and heat sink, that should allow a Pk-Pk voltage of about 70v.
Note that heat is still the biggest enemy and consideration, as it is in any MOSFET PA.
If you are opting for that much power, you probably would be better off designing or building a dual
IRF530 PA. The BITX3B PA would have to be considerably modified, even if the drain voltage were kept low.
You could probably get away with the current design (modified for impedance) with a IRF520, but
probably not a IRF530.
Check the internet; there are many designs out there.
john
AD5YE
|
Jorge:
Note that you cannot directly substitute a IRF530 for a IRF510.
That is because the input gate capacitance of the 510 is ~180 pF.
and the gate capacitance of the 530 is ~620 pF. That means the input impedance is
considerably different and needs compensation. There is also a difference in
the drain capacitance which will affect the LPF match.
If these are compensated for, with 20v on the drain, the Pk-Pk AC output voltage can be about
36-40v. (The maximum wattage handling ability of the 530 is about 85W.) Note that the heat sink
must be considerably increased in size.
If you want to increase the wattage that much, you should probably opt for a drain voltage of ~36v.
With a suitable matching network and heat sink, that should allow a Pk-Pk voltage of about 70v.
Note that heat is still the biggest enemy and consideration, as it is in any MOSFET PA.
If you are opting for that much power, you probably would be better off designing or building a dual
IRF530 PA. The BITX3B PA would have to be considerably modified, even if the drain voltage were kept low.
You could probably get away with the current design (modified for impedance) with a IRF520, but
probably not a IRF530.
Check the internet; there are many designs out there.
john
AD5YE
|
On 29/04/17 03:19, Jerry Gaffke via Groups.Io wrote:
I prefer to keep it all in one place.
That doesn't work, as things get lost even after just one day. [....] If your radio works, then you can just unsubscribe and
occasionally check
People like it here, and want to stay. Wiki is here: /g/BITX20/wiki Members are expected to Wiki things that they are find. What I'd like is a way to download all messages from the groups.io
website so I can sic an intelligent search tool on them. The
groups.io search bar is nearly unusable.
That's what a www forum is. With the current level of traffic, the group will implode as "unreadable". Too much data flow and not much of it usable after even just a week. Steve ZL1BHD
|
? ? ? Greetings to all, what power should I expect from an IRF530 powered by 20 Vdc in the linear of the BITX20 V3B ? Thank you. ? ?Jorge PY2PVT _._ --
? 73 de Jorge PY2PVT
? Campinas SP
? GG67MD
|
Re: Too Much Information?
On 29/04/17 05:16, Arv Evans wrote: [....] If we were to narrow the discussion parameters it might
decrease the value of the group as a comprehensive repository of BITX
information of all types. It needs to move to a forum. S
|
Re: Bitx40 vs the antenna beast
I. too, am warring with the "antenna beast". I live with my parents, and my dad doesn't want me running coax cables out through window panel feed-throughs or drilling holes in the upstairs walls, and the metal-framed windows are designed in such a way as to pinch a feed-through cable made of flat lead.
My solution will be to make a folded dipole, run around the wall just under the ceiling in my bedroom, and made of 300 ohm flat lead (I have 50 feet of the stuff), with the "legs" 20-1/2 feet long each (I have 41 linear feet of wall in my room). I will be using a 6:1 balun to impedance match (50 ohms out from the radio to the 300 ohm antenna), with an automatic antenna tuner (either my Elecraft T1 or one of my old but trusty LDG AT-11 tuners) between the rig and the balun. Probably won't work much past 40 meters, but it's better than nothing at all!
Rich KC8MWG
On Friday, April 28, 2017 6:13 PM, richard kappler <richkappler@...> wrote:
Fred,
You are a gentleman and a scholar, that is exactly the type of guidance I was looking for!
Cheers, Richard W2KAP?
On Apr 28, 2017 6:02 PM, "Dr Fred Hambrecht" < AAR4MI@...> wrote: Use the MFJ to determine where the antenna is resonant. If the frequency is below 7.285 decrease the ?amount of coil and recheck. Conversely if it is resonate above 7.286 you will have to add coil. ? v/r Fred W4JLE ? ? So I'm a new ham (General), as I've said before, and aside from a VHF/UHF HT, the BitX is my first (and presently only) radio. I'm in an apartment, so antenna choices are severely limited. I am currently running my BitX through a MFJ-1622, which is tapped coil 1/4 wave apartment antenna with a 5 foot whip and a counterpoise. ?(? ). I've NEVER been able to hear anything but static on my BitX40, and have done much troubleshooting, finding nothing amiss thus far (on the second one anyway, the first one I built is another story for another day). I took a wafg and figured it to be the antenna, ordered the parts for Jack's antenna analyzer, most of which still aren't here. Impatient as I am, I've sprung for an MFJ-259C antenna analyzer, which arrived about an hour ago, and sure as shootin', my antenna appears to be VERY out of whack.impedance is about 90 ohms, SWR up at 13.5 at freq 7.285. And now the question: Is this most likely the reason I've been able to hear nothing and no one has been able to hear me? Then I, of course, have to go OT a bit: Any suggestions as to how to adjust this antenna to something reasonable? Near as I can figure, it has three mechanical adjustments: placement of tap on coil, whip length, counterpoise length. I will, of course, spend the weekend adjusting everything, one thing at a time, small adjustments, until I figure it out, but if anyone has the antenna knowledge to give me a little guidance, it would sure save some time. If it's not the antenna, you'll be hearing from me. I've been trying to get on HF for about 2 months now. I've got me an itch that demands scratching! -- In any given circuit, the most expensive part will always sacrifice itself to protect the fuse.
|
Re: Bitx40 vs the antenna beast
Fred,
You are a gentleman and a scholar, that is exactly the type of guidance I was looking for!
Cheers, Richard W2KAP?
On Apr 28, 2017 6:02 PM, "Dr Fred Hambrecht" < AAR4MI@...> wrote: Use the MFJ to determine where the antenna is resonant. If the frequency is below 7.285 decrease the ?amount of coil and recheck. Conversely if it is resonate above 7.286 you will have to add coil. ? v/r Fred W4JLE ? From: [email protected] [mailto:[email protected]] On Behalf Of richard kappler
Sent: Friday, April 28, 2017 2:24 PM
To: [email protected]
Subject: [BITX20] Bitx40 vs the antenna beast ? So I'm a new ham (General), as I've said before, and aside from a VHF/UHF HT, the BitX is my first (and presently only) radio. I'm in an apartment, so antenna choices are severely limited. I am currently running my BitX through a MFJ-1622, which is tapped coil 1/4 wave apartment antenna with a 5 foot whip and a counterpoise. ?(? ). I've NEVER been able to hear anything but static on my BitX40, and have done much troubleshooting, finding nothing amiss thus far (on the second one anyway, the first one I built is another story for another day). I took a wafg and figured it to be the antenna, ordered the parts for Jack's antenna analyzer, most of which still aren't here. Impatient as I am, I've sprung for an MFJ-259C antenna analyzer, which arrived about an hour ago, and sure as shootin', my antenna appears to be VERY out of whack.impedance is about 90 ohms, SWR up at 13.5 at freq 7.285. And now the question: Is this most likely the reason I've been able to hear nothing and no one has been able to hear me? Then I, of course, have to go OT a bit: Any suggestions as to how to adjust this antenna to something reasonable? Near as I can figure, it has three mechanical adjustments: placement of tap on coil, whip length, counterpoise length. I will, of course, spend the weekend adjusting everything, one thing at a time, small adjustments, until I figure it out, but if anyone has the antenna knowledge to give me a little guidance, it would sure save some time. If it's not the antenna, you'll be hearing from me. I've been trying to get on HF for about 2 months now. I've got me an itch that demands scratching! -- In any given circuit, the most expensive part will always sacrifice itself to protect the fuse.
|
Re: Bitx40 vs the antenna beast
Use the MFJ to determine where the antenna is resonant. If the frequency is below 7.285 decrease the ?amount of coil and recheck. Conversely if it is resonate above 7.286 you will have to add coil. ? v/r Fred W4JLE ?
toggle quoted message
Show quoted text
From: [email protected] [mailto:[email protected]] On Behalf Of richard kappler
Sent: Friday, April 28, 2017 2:24 PM
To: [email protected]
Subject: [BITX20] Bitx40 vs the antenna beast ? So I'm a new ham (General), as I've said before, and aside from a VHF/UHF HT, the BitX is my first (and presently only) radio. I'm in an apartment, so antenna choices are severely limited. I am currently running my BitX through a MFJ-1622, which is tapped coil 1/4 wave apartment antenna with a 5 foot whip and a counterpoise. ?(? ). I've NEVER been able to hear anything but static on my BitX40, and have done much troubleshooting, finding nothing amiss thus far (on the second one anyway, the first one I built is another story for another day). I took a wafg and figured it to be the antenna, ordered the parts for Jack's antenna analyzer, most of which still aren't here. Impatient as I am, I've sprung for an MFJ-259C antenna analyzer, which arrived about an hour ago, and sure as shootin', my antenna appears to be VERY out of whack.impedance is about 90 ohms, SWR up at 13.5 at freq 7.285. And now the question: Is this most likely the reason I've been able to hear nothing and no one has been able to hear me? Then I, of course, have to go OT a bit: Any suggestions as to how to adjust this antenna to something reasonable? Near as I can figure, it has three mechanical adjustments: placement of tap on coil, whip length, counterpoise length. I will, of course, spend the weekend adjusting everything, one thing at a time, small adjustments, until I figure it out, but if anyone has the antenna knowledge to give me a little guidance, it would sure save some time. If it's not the antenna, you'll be hearing from me. I've been trying to get on HF for about 2 months now. I've got me an itch that demands scratching! -- In any given circuit, the most expensive part will always sacrifice itself to protect the fuse.
|
I'll be here in the PNW, if I don't hear anything I'll call CQ BITX -- Ryan Flowers W7RLF?
|
OK, BITX QSO night on Sunday, April 30 at 9pm Eastern, on 7195. Call cq and say you are running BITX QRP. Keep calling cq frequently, and listen very closely for responses, they may be faint.
If you get a big gun to respond (over 10 Watts), ask him to relay to any other rigs that he hears. Watch this forum if there is QRM on 7195. We will coordinate an alternate frequency here. (Proposed alternate: 7188)
Please report BITX to BITX QSOs made here.
Lets hope for good propagation!
|
Re: Too Much Information?
Am hoping one of the other admins could look into this. ?Having learned to program on a PDP-8, ?I agree it would be huge. ?The kids today would not. ?When we hit the GByte limit a few months ago, it was images that took up most of that, messages are on the order of a couple hundred MBytes. ?At current prices per GByte for a USB flash drive, that's about $0.10 worth. ?And could transfer in seconds for those with a decent internet connection. ?
?
On Fri, Apr 28, 2017 at 11:19 am, Arv Evans wrote:
The amount of stored data since the first BITX would be huge because it includes many discussions as each new design became available. ?BITX20, BITX20A, BITX17A, MKARS-80, BITX40A, BITX-V3, Minima, BINGO, BITX-40, and many more designs are represented in the history.
?
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Raj vu2zap