NAQCC article on ubitX by W7HD
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Ron W7HD - NAQCC#7587 OMISS#9898 KX3#6966 LinuxUser#415320
Editor OVARC newsletter
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Re: ?- How high SWR before smoke?
The RD16HHF1's do have some advantages.
Primary advantage is that the tab is connected to the source, not the drain,
so you can heatsink them directly to the chassis if you wish without using any electrical isolation.
But an IRF510 on a properly done heatsink can dissipate about the same power.
They are capable of more power out at 12v than the IRF510's, but you would have
to rewind some transformers to take advantage of that.
Others here will have other points to make.
For example, when operating at 12v the RD16HHF response might be a bit more linear.
Though if you are worried about spurious emissions the FET choice is not much of a factor here.
I doubt they would be any more robust than the IRF510's.
And I doubt it's worth the trouble.
On the other hand, could be fun to try.
> if you replace the output transistors to the RD16HHF1 that many are doing, the data sheet says a 20:1 SWR.?
Many here have demonstrated that the IRF510's are capable of dealing with much higher SWR's than 20:1.
No antenna connected means infinite SWR.
And the RD16HHF1 will have the same trouble getting heat transferred from die to tab that the IRF510 does.
Jerry
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On Thu, Jul 5, 2018 at 12:45 pm, <trcarswell@...> wrote:
On Thu, Jul 5, 2018 at 12:40 pm, Ralph Mowery wrote:
RD16HHF1
At 4.75 each(RFParts) I may just do that!! ... are they "direct" replacements ???
(other than pinout)
Trip - KT4WO
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Re: Easy, Inexpensive Cooling Fan, Excelway Case
Here you are. -- Lee - N9LO? "I Void Warranties"
?
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Re: ?- How high SWR before smoke?
On Thu, Jul 5, 2018 at 01:43 pm, Ralph Mowery wrote:
Look here for some info on the replacing of the parts.
I've heard that the v4 of the ?B board has pads for the RD16HFF1s?? Has anyone posted something about swapping out or pictures of the board there? 
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Re: ?- How high SWR before smoke?
Look here for some info on the replacing of the parts.? RF parts does have a $ 20 minimum order and about a $ 8 or so shipping and handling. That is where I bought some a few months back.? I did do a few other modifications tothe uBitx in the power chain.? I am not planning on battery power ,so the current drain did not matter to me, I just wanted to get the power up to 5 or 10 watts on 10 meters to drive some transverters at a later time.
On Thu, Jul 5, 2018 at 3:45 PM, <trcarswell@...> wrote: On Thu, Jul 5, 2018 at 12:40 pm, Ralph Mowery wrote:
RD16HHF1
At 4.75 each(RFParts) I may just do that!! ... are they "direct" replacements ???
(other than pinout)
Trip - KT4WO
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I was able to use a higher current supply for the ?BITX today for WSPR TX.
As I reported previously, my 2A supply tripped out on 80 M.
With the larger supply, the rig drew around 4A on both 160 and 80M, and 1.2A on 40M.
Does this seem reasonable?
Does current go up with a badly mismatched antenna?? I did not make any connections on 160 or 80.
One of the projects in the queue is to use the SDRplay analyzer software to check the SWR on various bands.
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Re: ?- How high SWR before smoke?
On Thu, Jul 5, 2018 at 11:37 am, <trcarswell@...> wrote:
I have read that very high ref. power will blow fuse and/or finals.
Well, before I added the fan to mine, I accidentally did a full 40 M WSPR transmission, about two minutes full blast digital, with no antenna connected.? The PA sinks got way, way hot, and somehow the IR510s survived.
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Dex? ZL2DEX
I think that several are already using the Raduino, or an alternative Raduino from other
persons.? Since your BITX40 is simpler than a uBITX you should already have enough
spare pins to use a rotary encoder (it only takes 2 digital inputs for the encoder and one
more for the push-switch).? Are you writing your own Raduino code or planning on using
software from someone else??
Arv? K7HKL
_._
On Thu, Jul 5, 2018 at 1:55 PM Dexter N Muir < dexy@...> wrote: Yippee! More I/O! Now I might be able to actually use the encoder for my '40! (Anyone done so already?)
VY 73!
Dex, ZL2DEX
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Yippee! More I/O! Now I might be able to actually use the encoder for my '40! (Anyone done so already?)
VY 73!
Dex, ZL2DEX
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Re: Removing insulation from fine wires
I usually use a pair of strippers. They usually use their teeth.
- Rich WB2GXM
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On 7/3/18, Adrian <a.futrill@...> wrote: I used to use my teeth aswell until stripping wire one day broke a chunk of
tooth off. Now use my thumb nail and finger
Adrian
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Re: ?- How high SWR before smoke?
On Thu, Jul 5, 2018 at 12:40 pm, Ralph Mowery wrote:
RD16HHF1
At 4.75 each(RFParts) I may just do that!! ... are they "direct" replacements ??? (other than pinout) Trip - KT4WO
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Re: ?- How high SWR before smoke?
While not what you asked, but if you replace the output transistors to the RD16HHF1 that many are doing, the data sheet says a 20:1 SWR.? Plus you get the benefit of being able to directly ground the tabs to a heat sink.? Just be sure to swap the leads as two of them are reversed.
On Thu, Jul 5, 2018 at 3:28 PM, <trcarswell@...> wrote: Tnx Jerry,
I have a small fan that will be blowing on the 510 heatsinks,(via switch) so hope that will tame that beast.
And will be using SO-239 for ant.? I just want it as robust as can be before hitting the trail.
It will weigh more than I want, but hope it's worth it. And a heck cheaper than an 817!!
Tnx agn de Trip - KT4WO
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Re: ?- How high SWR before smoke?
Tnx Jerry,
I have a small fan that will be blowing on the 510 heatsinks,(via switch) so hope that will tame that beast.
And will be using SO-239 for ant.? I just want it as robust as can be before hitting the trail.
It will weigh more than I want, but hope it's worth it. And a heck cheaper than an 817!!
Tnx agn de Trip - KT4WO
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Re: ?- How high SWR before smoke?
Your uBitx will be fine with an SWR of 2:1.
Your primary concern is heat on those IRF510's.
A dead short might eventually cause the IRF510's to get too hot (as could operating digital modes continuously).
If that's a concern, monitor the IRF510 heatsinks with a finger, should not get uncomfortably hot.
If powering the IRF510's from something close to 12v,?
I seriously doubt it would blow due to overvoltage if the antenna were absent.
Lots of folks in the forum have tested the open antenna port thing.
The BNC panel mount connector that came with some of the uBitx kits is not machined to spec.
Center pin from your antenna coax may not connect well with the center pin of the panel mount connector.
Jerry, KE7ER
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On Thu, Jul 5, 2018 at 11:37 am, <trcarswell@...> wrote:
I just RX my uBITx and have in on bench. I would like to add SWR bridge inside case.
I have read that very high ref. power will blow fuse and/or finals. So, I would like to use
resistive bridge as the SWR indicator. If I recall, the max SWR from a resistive style
bridge is 2:1? (??).?? Will the finals handle this ??
My uBITx is for the "trail" so don't want to be popin' fuses or finals while out.
Thoughts?
Trip - KT4WO?
trcarswell@...
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?- How high SWR before smoke?
I just RX my uBITx and have in on bench. I would like to add SWR bridge inside case. I have read that very high ref. power will blow fuse and/or finals. So, I would like to use resistive bridge as the SWR indicator. If I recall, the max SWR from a resistive style bridge is 2:1? (??).?? Will the finals handle this ?? My uBITx is for the "trail" so don't want to be popin' fuses or finals while out. Thoughts? Trip - KT4WO? trcarswell@...
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Re: Easy, Inexpensive Cooling Fan, Excelway Case
On Thu, Jul 5, 2018 at 10:16 am, Lee wrote:
...a temperature controlled fan controller, $3.58.
Hi, Lee.? Do you have a link for that controller? I see a few that are PWM, which might be RF noisy. Thanks!
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Totally agree with this, and your other posts in this thread.
My post attempted to figure out how your deliberately broken strncpy() example
managed to terminate the destination string with a null (an 8 bit char with a value of zero)..
Conclusion:? totally indeterminate, depends largely on how the compiler decides to allocate RAM.
There just happened to be RAM with a zero in it immediately after your buffer.
But you know all that.
Just spelling it out for any others attempting to follow the conversation.
Jerry, KE7ER
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On Thu, Jul 5, 2018 at 10:23 am, Jack Purdum wrote:
The strncpy() function is much safer than strcpy() so long as the bytecount you give it agrees with the buffer size.
?
That's always been true, but is not what was originally said. The implication on the first go around was that using strncpy() protects you from buffer overflow. It does not. There is nothing in the strn*() functions that protect you from buffer overflow. Your statement recognizes that fact by saying that the programmer is responsible for buffer overflow, not the string library.
?
Jack, W8TEE
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I was wondering how they simulated that old-timey glow.
¡°VU Meter with back light by filament¡±
It¡¯s not simulated!
Now if they would just heat distress the meter face it could be from a HT32.
on order.
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Re: Easy, Inexpensive Cooling Fan, Excelway Case
Great approach. After all, it is temperature we are trying to dissipate.?
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Re: Easy, Inexpensive Cooling Fan, Excelway Case
You could put a cap in to hold the receive on for a couple of seconds like the old Browning Eagles did.. makes a ¡°lovely¡± squeal to let everyone know you had pushed the PTT button.. goes great with that Roger Beep....lol
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Lee
Arvo W0VRA