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Re: filter shielding?
Jim Strohm
On Jun 27, 2004, at 6:16 AM, vdberghak wrote:
Looking at the pictures of other builders, I see several 'islands',The only reason(s) I can think of _not_ to make 'em float in the air is that this technique has the potential to make the circuit sensitive to microphonics. And in a high-vibration or high-shock environment such as portable or mobile use, the solder joints would tend to fracture and eventually cause intermittent failures long before any visual breakage was apparent. What I also saw is that the x-tal filter has no kind of shielding.Well, you could take the PCB scraps you saved by not using "island" construction, and use it to make shielding. What's that old bromide -- "You can never be too rich, too thin, or have too many friends" -- add to that the idea that your electronics can never have too much shielding. Jim N6OTQ |
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Re: PCB
Hans Summers
While I think on, Plumb Centre in the UK have a 1/2"What is a "delta" tap washer? I'd be careful... When I bought my tap washers there were "delta" washers and ordinary ones. But I don't recall what the difference was. Anyone know? I got my (non-"delta") washers at my local hardware store where they sell a pacl of 3 for ?0.45 including VAT. I'm happy to send some to whoever wants them. Farhan is also talking of sending me 1000 from India, and the TV baluns. 73 Hans G0UPL (Again owing many people emails, pls QRX) |
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filter shielding?
Hi all,
I had the intention to build this transceiver when a friend of me brought this Yahoo group under my attention. Too bad, now I spend all the time on reading all information instead of building it ;-) The nice thing I like is that the design is so basic, so straightforward and everything (except the final stage) broadband that it can be adjusted easily to everyones needs. Because I have several x-tals with a frequency of 4.9152 MHz this will be the IF frequency and because I want to make it for 18 Mhz, I will try to cover the phone part with a VXO on about 13 MHz. Looking at the pictures of other builders, I see several 'islands', I do not build that way, I just solder every component to each other (above the copper surface, only connected to it where needed). What I also saw is that the x-tal filter has no kind of shielding. Is it worth seperate the input/output of the filter with a kind of shielding to prevent the signal passing it? Good luck all, Chris, PA3CRX |
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Re: Audio amp schematic
开云体育Hi
?
according to my
diagram? +V should be on pin 6 as mentioned ..
?
looks like pins 5 and 6 need to be changed
for each other as output must be on 5 and volts in on 6
?
Charles
G4VSZ -----Original Message----- Anyone checked this - is +V on pin 5
correct?From: Mark [mailto:Mark@...] Sent: 27 June 2004 09:47 To: BITX20@... Subject: [BITX20] Audio amp schematic Should it not be on pin 6? Mark. |
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PCB
Bill Schofield
Hi all. I have posted a pic, I hope in the photos section. This is my
first attempt at using Press & Peel to create PCB's as I usually use the island method etc for my projects. I was so impressed with the results, to say this was my first attempt, I made the effort to tell you all about it. See the site at I wish everyone good luck with the project. While I think on, Plumb Centre in the UK have a 1/2" Delta Tap Washer Cat No C54018 in stock. The price is ?1.80 plus VAT for 10 washers. Not sure if they will post but they have branches everywhere. All the best, de Bill G0BAK. |
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Re: Audio amp schematic
Ashhar Farhan
mark,
toggle quoted message
Show quoted text
check the corrected schematic on . the earlier circuit had a typo. - farhan On Sun, 27 Jun 2004, Mark wrote:
Anyone checked this - is +V on pin 5 correct? |
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Please suggest for alternative 'linear amplifier module'
MILAREPA
开云体育Dear forum,
The IRF510 and 2N2218 is not available here in
INDONESIA,
?
-Could you suggest an alternative for 'linear amplifier
module' ?
?
-Can I just use:
HF BANDS QRP LINEAR AMPLIFIER?- 4WATT or
TEN WATT LINEAR AMPLIFIER all by Harry Lythall -
SM0VPO
Since 2SC.....( Japanese) transistors are available here. ?
?
-What? module ( coil, capacitor, x-tals) to
change?if need another band say 10MHz ?
?
Thank you. |
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Re: manhattan style pads
Wes Hayward
开云体育Hi All,
?
Actually, I think that the Manhattan in the QRP
construction method really refers to the use of straight wires on a 90 degree
grid.?? At least that is where the term
originated.?????Typical integrated circuits use a
layout that follows a Manhattan format.? A recent reference is John Baliga,
"Chips Go Vertical," IEEE Spectrum, March, 2004,
pp43-47.????
?
I agree with Hans -- I have really seen no
difference between construction on a ground plane when using pads and building
without them, other than building without is
faster.????? There is rarely a need to go as high as
10M with the resistors if you don't have them around.?? Something much
smaller values will work just as well.
?
My son and I picked the term "ugly" on our 1981 QST
paper "The Ugly Weekender" for a specific reason:?? We wanted to
emphasize that there is no relationship between circuit performance and the
"pretty" nature of the construction, including that on a printed
board.?? In this case, it is the use of extensive ground plane that
makes the circuitry work well.
?
73, Wes
W7ZOI
?
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Re: manhattan style pads
Bruce Raymond
开云体育Mark
& Hans,
?
Many
thanks for your replies.? Small rectangular pads should work
just
fine,
and those I can come up with - I don't know why it didn't occur
to
me.
?
Thanks
for your help,
Bruce/nd8i
?
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Re: manhattan style pads
Hans Summers
Mark, Bruce et al
toggle quoted message
Show quoted text
I don't think the difference between "ugly" and "Manhatten" methods is all that much. My method is a bit of a hybrid I suppose. Mostly ugly. But if I find a point needs to be better anchored I sometimes use a 10M resistor to ground (ok for low impedance signal points) or a .22uF capacitor to ground (ok for dc voltage points). Sometimes I find I want pads. I mounted all the BITX20 inductors and trifilar transformers on pads. But not nice circular pads like in the copper island construction kit. I just find scraps of PCB stock and cut them up into rough squares approximately 5mm x 5mm with a wire cutter. They're ugly but it works and takes literally seconds. 73 Hans G0UPL -----Original Message-----
From: Mark Jones <Mark@...> To: BITX20@... <BITX20@...> Sent: Sat Jun 26 16:39:19 2004 Subject: RE: [BITX20] manhattan style pads Bruce I bought a "Copper island Construction Kit" but they ceased trading a while ago, I found someone (and I can't remember who or find the e-mails) that sent me some replacement (re-stock) pads via the GQRP reflector. I just paid the postage - a great deal and very helpful, he said that a friend of his was able to make them at work. Sorry I can't help more - I thought about making some but it was just to tricky. Mark. G0MGX -----Original Message----- From: nd8i [mailto:bruceraymond@...] Sent: 26 June 2004 16:28 To: BITX20@... Subject: [BITX20] manhattan style pads I've been using ugly-style construction, which has worked quite well. I've noticed a bunch of constructors have used Manhattan- style construction. Not being willing to leave well enough alone, I want to give it a try. Where do people get the pads? Or how does one make them from blank pcb material? I suspect that trying to punch them out of pcb material is a pretty slow and tedious process, so I suspect there must be a better alternative. tia, Bruce Yahoo! Groups Sponsor ADVERTISEMENT click here _____ Yahoo! Groups Links * To visit your group on the web, go to: * To unsubscribe from this group, send an email to: BITX20-unsubscribe@... * Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service. |
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Re: manhattan style pads
Mark Jones
开云体育Bruce
?
I
bought a "Copper island Construction Kit" but they ceased trading a while ago, I
found someone (and I can't remember who or find the e-mails) that sent me some
replacement (re-stock) pads via the GQRP reflector. I just paid the postage - a
great deal and very helpful, he said that a friend of his was able to make them
at work.
?
Sorry
I can't help more - I thought about making some but it was just to
tricky.
?
Mark.
G0MGX
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manhattan style pads
nd8i
I've been using ugly-style construction,
which has worked quite well. I've noticed a bunch of constructors have used Manhattan- style construction. Not being willing to leave well enough alone, I want to give it a try. Where do people get the pads? Or how does one make them from blank pcb material? I suspect that trying to punch them out of pcb material is a pretty slow and tedious process, so I suspect there must be a better alternative. tia, Bruce |
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Re: Atachments
Hans Summers
i am new ot yahoo groups. i don't know if you canIt's definitely possible, I am a member of another group where the members do post pictures to the photos folder, and don't have to be administrator. Have a look at the folders on the group home page I think the way it works is: if you send an attachment to the group, email recipients do receive it. But people who have set up their account to not receive emails, but instead use the web interface, cannot view the photos. Therefore it's best to use the group folders rather than attach things. 73 Hans G0UPL |
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BITX20 component list
ik1zyw
Hi!
Has anyone attempted to list all BITX20 components? I haven't found any link on Ashan's page. Here is my attempt at listing all components, except for the IRF510 PA (had no time). Please warn me off the list if corrections are needed. 73, Paolo IK1ZYW CAPACITORS 0.001u 2 0.1u 34 100p 3 10p 4 1u elec 2 2.2p 2 220p 3 22p var 6 365p var 1 47p 3 50u elec 6 560p 2 56p 1 RESISTORS 1/4W 10 9 22 1 100 13 220 14 470 2 100 lin 1 10k 3 10k lin 2 120k 2 1k 13 220k 1 2k2 1 2k2 9 4k7 3 XTAL 10MHz 5 (10) TRANSISTOR BC547 14 or 2N2222 IC LM386-N1 1 DIODES 36V zener 1 9.1V zener 1 1N4148 13 TRANSFORMERS INDUCTORS see text OTHER Microphone 1 Loudspeaker 8ohm 1 |
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Atachments
Sam Caldwell
G'day Troops,
I note that one or two contributors have mentioned attachments (which do not appear). At the same time there are some photographs which CAN be accessed. Being a Bear of Very Little Brain, I would appreciate it if some kind person would explain - particularly as in the near future there will no doubt be proud builders anxious to display their new-born transceivers. Regards, Sam C. |
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How to post schematics, images, etc.???
k7hkl_arv
Help please...
I'm new to this forum thing, so I have to ask "How does one go about posting a schematic or picture of BITX related info"? I sent an attached file with one of my posts and now my email post is there but the attached .gif file is referenced as "Not Saved". )-8 Thanks, Arv - K7HKL _._ |
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Re: Atachments
Ashhar Farhan
yahoo groups doesnt not retain attachments. if you can forward the
toggle quoted message
Show quoted text
pictures to me, i canupload them on the folder. i am new ot yahoo groups. i don't know if you can directly upload the pictures without being a moderator. - farhan On Sat, 26 Jun 2004, Sam Caldwell wrote:
G'day Troops, |
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Re: BFO Clarification?
Ashhar Farhan
Mark,
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Show quoted text
USB requires setting the carrier to the lower edge of the filter's passband and LSB requires setting the carrier to the upper edge. given that we are sourcing crystals from varied places, it probable that you will have to pull the crysal frequency down for USB and pull it up for LSB. adding a small series capacitance to the crystal pulls the frequency up (good for LSB). to pull the frequency down you need inductive capacitance in series with the crystal. it is often difficult to estimate just how much (capactiance/inductance) will be required to position the bfo correctly. in case of LSB, a 22pf trimmer in series with the crystal can be tweaked to get the proper results. in case of USB, i have found about 5uH to be ideal for the crystals that i have used (3 builds so far). this may not work for you. so you can either play with the number of turns on L3, or use the inductor with a capactiance in series to vary the net reactance to set the frequency properly. - farhan On Fri, 25 Jun 2004, Mark wrote:
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