R: Re: [BITX20] BITX40 Sensitivity
sensitivity or not sensitivity.............. How many don't have see that? https://www.youtube.com/watch?v=q2v4Q69bs8g ?73 de Giovanni (i7iwn)
----Messaggio originale----
Da: "Michael Hagen" <motdog@...>
Data: 11/07/2017 15.15
A: <[email protected]>
Ogg: Re: [BITX20] BITX40 Sensitivity
If you got real 50 Ohms, the Attenuator is
usually 50 Ohms in dB (Power).? You can calculated it.? But you
have to know what is coming out of the generator.? You can
convert between power and uV with P = E squared/R(that is 50
ohms).? There are also nice charts you can search for, or make
your own in Excel.
Measure your output of the generator into the
Attenuator with X10 probe and highest freq scope you can get.?
But a bigger signal ahead of the Attenuator are a
lot easy to measure.? I use my attenuator all the time, maybe 80
dB cranked in?
I can't recommend the K5BCQ more, it is cheap and
works great.? You can make you own real easy.? 1W mox resistors
from Mouser work fine.
Make some 20 dB, 6 and 3 stages?
Mike, WA6ISP
On 7/11/2017 4:25 AM, C¨¦sar EA3IAV
wrote:
But... If I use an attenuator that is "analog"... How
am I going to know the amount of microvolts that I am iinjecting
into the BITX?
--
Mike Hagen, WA6ISP
10917 Bryant Street
Yucaipa, Ca. 92399
(909) 918-0058
PayPal ID "MotDog@..."
Mike@...
|
Adrian,
I use extra strong glasses and lots of light.
I flux the area and use a tweezer to put in place and while holding the chip down i just tack one pin. I let it cool and solder the remaining pins. Then resolder the pin i tacked.
Joe
VE1BWV
On Tue, Jul 11, 2017, 9:38 AM Jack Purdum via Groups.Io <econjack= [email protected]> wrote: Adrian:
SMD's aren't as bad as you might think. Try this: On one leg of U2's PCB pad, place the thinnest touch of solder you can ("tinning" the pad). Using bent-tip tweezers (I bought one like this--ebay #131672888160), orient the SMD into place and touch the tinned lead with the iron while pressing down on U2. Don't actually try to hold it with the tweezer tips, just a downward pressure on the chip. (I've learned that trying to hold an SMD with tweezers causes they to reach terminal velocity, placing them in an undetectable orbit.) That should solder that leg enough to allow you to lightly solder the rest of the legs in place. You may need to touch up the first leg after the others are done.
Jack, W8TEE
I finally received all of the components for the assembly of the W8TEE VFO today. Question how on earth do you fit U2 on the board? My hands shake at the best of times.?
Adrian VK4KL
|
Re: Exposing Fake IRF510's, and a cheap antenna pole alternative
I looked too at the fishing poles.
I would bet they are all of the same "crappyness".
I doubt if any are much better than others??
Maybe all made by the same Manf?
I may find the Jack pole you mentioned?
Mike, WA6ISP
On 7/11/2017 6:03 AM, Michael Davis
wrote:
Unfortunately the 7.2 meter is sold out. The next shorter one is 6.3 meters. There are others on eBay in the 7.2 meter length for $10-$12. Not sure of the quality though. I have the 31 foot Jackite pole. Pricey ($70) but nice.
Sent from Mike's iPad WA1MAD
--
Mike Hagen, WA6ISP
10917 Bryant Street
Yucaipa, Ca. 92399
(909) 918-0058
PayPal ID "MotDog@..."
Mike@...
|
If you got real 50 Ohms, the Attenuator is
usually 50 Ohms in dB (Power).? You can calculated it.? But you
have to know what is coming out of the generator.? You can
convert between power and uV with P = E squared/R(that is 50
ohms).? There are also nice charts you can search for, or make
your own in Excel.
Measure your output of the generator into the
Attenuator with X10 probe and highest freq scope you can get.?
But a bigger signal ahead of the Attenuator are a
lot easy to measure.? I use my attenuator all the time, maybe 80
dB cranked in?
I can't recommend the K5BCQ more, it is cheap and
works great.? You can make you own real easy.? 1W mox resistors
from Mouser work fine.
Make some 20 dB, 6 and 3 stages?
Mike, WA6ISP
On 7/11/2017 4:25 AM, C¨¦sar EA3IAV
wrote:
But... If I use an attenuator that is "analog"... How
am I going to know the amount of microvolts that I am iinjecting
into the BITX?
--
Mike Hagen, WA6ISP
10917 Bryant Street
Yucaipa, Ca. 92399
(909) 918-0058
PayPal ID "MotDog@..."
Mike@...
|
Re: Exposing Fake IRF510's, and a cheap antenna pole alternative
Unfortunately the 7.2 meter is sold out. The next shorter one is 6.3 meters. There are others on eBay in the 7.2 meter length for $10-$12. Not sure of the quality though. I have the 31 foot Jackite pole. Pricey ($70) but nice.
Sent from Mike's iPad WA1MAD
|
Re: Exposing Fake IRF510's, and a cheap antenna pole alternative
Ryan:
Thanks for the post. Also, at the bottom of the antenna pole article is a link to BITX40: Is It A Good?Beginners HF?Radio. I also found it interesting as it shows what can be done with a little work and a $10 case from Banggood. It also mentions Peter Parker's ebook: Minimum QRP, which I have read. Most of us here are familiar with Peter's work and the book is definitely worth a read, especially for someone just getting started in QRP.
Jack, W8TEE
From: Ryan Flowers <geocrasher@...>
To: [email protected]
Sent: Tuesday, July 11, 2017 2:39 AM
Subject: [BITX20] Exposing Fake IRF510's, and a cheap antenna pole alternative
Hello all! I thought I'd share links to a couple of things I've posted lately that are relevant to the group. The first is about how easy it is to get cheap but fake IRF510's (and how to avoid them) ?and the second about how to get cheap (but real actual working) 23 foot (7.2m) telescopic poles for portable antennas etc. I hope you enjoy them :)
73! -- Ryan Flowers W7RLF
?
?<-- Learn how to go digital on the BITX40
|
Adrian:
SMD's aren't as bad as you might think. Try this: On one leg of U2's PCB pad, place the thinnest touch of solder you can ("tinning" the pad). Using bent-tip tweezers (I bought one like this--ebay #131672888160), orient the SMD into place and touch the tinned lead with the iron while pressing down on U2. Don't actually try to hold it with the tweezer tips, just a downward pressure on the chip. (I've learned that trying to hold an SMD with tweezers causes they to reach terminal velocity, placing them in an undetectable orbit.) That should solder that leg enough to allow you to lightly solder the rest of the legs in place. You may need to touch up the first leg after the others are done.
Jack, W8TEE
From: Adrian <a.futrill@...>
To: [email protected]
Sent: Tuesday, July 11, 2017 2:41 AM
Subject: Re: [BITX20] - W8TEE board
I finally received all of the components for the assembly of the W8TEE VFO today. Question how on earth do you fit U2 on the board? My hands shake at the best of times.?
Adrian VK4KL
|
That looks very good you have done a first class job?
On 11 Jul 2017 13:00, "Vince Vielhaber" < vev@...> wrote:
Do you remember what model that one is?? 1120 perhaps?
Thanks!
Vince.
> It is perfectly possible. I have an mdt on a Peli Case and it is very
> sturdy. The difficulty is to cut it tight enough in order to get a perfect
> size
>
--
? ?Michigan VHF Corp.? ?? ?
? ? ? ? ? ? ? ?
|
Do you remember what model that one is? 1120 perhaps?
Thanks!
Vince.
toggle quoted message
Show quoted text
It is perfectly possible. I have an mdt on a Peli Case and it is very
sturdy. The difficulty is to cut it tight enough in order to get a perfect
size
--
Michigan VHF Corp.
|
Re: Additional BPF's for other Bands
Hi the links you posted are not working I would like to see one for 60m and 80 I am sorted for lpf for 80m / 60m?
On 11 Jul 2017 12:41, "KF5GLB John" < KF5GLB@...> wrote: Thank you for the info. Keep up the good work? I'll build one for mine 73 John
Sent from my iPhone A few weeks ago I uploaded LTSpice plots and schematics for other bands, 80m 60m and 20m.
I finally got some time to build the 20m BPF. Even though the plot was good, the BPF did not work. I double and triple checked connections and components, but no go.
So I pulled out the bible (EMRFD) and read up on TTC, triple tuned circuits. I haven't down this kind of math since the 80's and it was beyond me.
Low and behold on Page 6.77 Figure 6.135 was a chart of L's and C's for different bands. So I built the 20m version and it works great.
Once the UPLOAD button comes back, I will load the plot and schematic to the files.
Meanwhile if anyone is interested, I'm attaching ?a plot and schematic.
73
Ken VA3ABN
<Bitx40-20BPF-Plot.png>
<Bitx40-20BPF-Schem.png>
|
Use a step or a bunch of fixed attenuators. 2mv is -41dbm. Raj and I
were still hearing our generators at -130 (which is 0.07uv). See if you
can find 3 30db fixed attenuators and you'll be good. Then for the
measurement, use a chart (or do the math). Here's a chart that covers
0dbm to -140dbm in 1db steps.
Vince.
toggle quoted message
Show quoted text
But... If I use an attenuator that is "analog"... How am I going to know
the amount of microvolts that I am iinjecting into the BITX?
--
Michigan VHF Corp.
|
Re: Additional BPF's for other Bands
Thank you for the info. Keep up the good work? I'll build one for mine 73 John
Sent from my iPhone
toggle quoted message
Show quoted text
On Feb 4, 2017, at 7:40 PM, Ken < chase8043@...> wrote: A few weeks ago I uploaded LTSpice plots and schematics for other bands, 80m 60m and 20m.
I finally got some time to build the 20m BPF. Even though the plot was good, the BPF did not work. I double and triple checked connections and components, but no go.
So I pulled out the bible (EMRFD) and read up on TTC, triple tuned circuits. I haven't down this kind of math since the 80's and it was beyond me.
Low and behold on Page 6.77 Figure 6.135 was a chart of L's and C's for different bands. So I built the 20m version and it works great.
Once the UPLOAD button comes back, I will load the plot and schematic to the files.
Meanwhile if anyone is interested, I'm attaching ?a plot and schematic.
73
Ken VA3ABN
<Bitx40-20BPF-Plot.png>
<Bitx40-20BPF-Schem.png>
|
But... If I use an attenuator that is "analog"... How am I going to know the amount of microvolts that I am iinjecting into the BITX?
|
That one is still going to require attenuation. The lowest it puts out is
2mv and you're going to need .1uv or less for sensitivity measurements.
Vince.
toggle quoted message
Show quoted text
Really cool one! I have just ordered the 30mhz vesion.
I am new to this things??
I have got an computer oscilloscope "Picoscope 2208" with limited signal
generator functionality
I guess you inject signal directly to BITX antenna from very low output to
higher output to see when the bitx detects the signal...
--
Michigan VHF Corp.
|
Re: Exposing Fake IRF510's, and a cheap antenna pole alternative
I hope mine are not fakes I have had the parts over 2 years?
On 11 Jul 2017 08:37, "Mvs Sarma" < mvssarma@...> wrote: Ryan,
?IRF510 like? devices as we get from International rectifiers are fine. Many others make IRF510, like VISHAY, Fairchild, ONsemi, many, many. I do agree that buying 10cents IRF and expecting quality, is funny. ?any item has some reasonable price tag. We , I suppose, need not go for alternatives just for sake of cost. As far as , ebay is concerned, if? the description section of any item shows that the item as "UNBRANDED/ GENERIC" we should avoid. Regards ?sarma vu3zmv
|
Re: Exposing Fake IRF510's, and a cheap antenna pole alternative
Ryan,
?IRF510 like? devices as we get from International rectifiers are fine. Many others make IRF510, like VISHAY, Fairchild, ONsemi, many, many. I do agree that buying 10cents IRF and expecting quality, is funny. ?any item has some reasonable price tag. We , I suppose, need not go for alternatives just for sake of cost. As far as , ebay is concerned, if? the description section of any item shows that the item as "UNBRANDED/ GENERIC" we should avoid. Regards ?sarma vu3zmv
On Tue, Jul 11, 2017 at 12:09 PM, Ryan Flowers <geocrasher@...> wrote: Hello all!
I thought I'd share links to a couple of things I've posted lately that are relevant to the group. The first is about how easy it is to get cheap but fake IRF510's (and how to avoid them) ?and the second about how to get cheap (but real actual working) 23 foot (7.2m) telescopic poles for portable antennas etc. I hope you enjoy them :)
73!
--
Ryan Flowers W7RLF
?
?<-- Learn how to go digital on the BITX40
|
It is perfectly possible. I have an mdt on a Peli Case and it is very sturdy. The difficulty is to cut it tight enough in order to get a perfect size 
|
Re: Exposing Fake IRF510's, and a cheap antenna pole alternative
I wish I had read this before. I reciently purchased 5 IRF510 from Ebay.?I assume they are bad boys
|
I finally received all of the components for the assembly of the W8TEE VFO today. Question how on earth do you fit U2 on the board? My hands shake at the best of times.?
Adrian VK4KL
|
Exposing Fake IRF510's, and a cheap antenna pole alternative
Hello all! I thought I'd share links to a couple of things I've posted lately that are relevant to the group. The first is about how easy it is to get cheap but fake IRF510's (and how to avoid them) ?and the second about how to get cheap (but real actual working) 23 foot (7.2m) telescopic poles for portable antennas etc. I hope you enjoy them :)
73! -- Ryan Flowers W7RLF
?
?<-- Learn how to go digital on the BITX40
|
KF5GLB John
