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Tap Washers
Bill Schofield
Hi All, Just to clarify, the Delta Washers I mentioned in the earlier
post are shaped more like a standard Torroid a little bigger than a T 50 and not as big as a T68 so I guess around a T55????? A standard 1/2 inch or basin tap washer in the uk is much bigger and the hole in the centre is quite small. I did purchase some of these also to compare, Catalogue no C54012 ?1.29 + VAT for 10 same Supplier. I use a PIC LCD Capacitance and Inductance meter that I made last year to give me the values of the coils, as yet I have not made them for the BITX. As mentioned in another posting, the core for the winding can be made out of various things, ball point pen plastic etc. When I wind the coils I will give some uH values from my meter. All the best and happy constructing, de Bill G0BAK. |
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"delta" washers & Pads versus point-to-point wiring
Arvid Evans
Hi
After reding over today's posts...here are a couple of thoughts and comments: 1) The manufacturer and model number for the faucet washer used in BITX20 coils is probably much ado about a triviality. The requirement for air-core (or nylon core, to be more correct) toroid coils in your BITX20 is a reference to the shape and to the absence of ferrite material in the magnetic field. I suspect that if you wanted you could use 'slices' from the body of a plastic ball-point pen. I used 1/4 inch wide slices from a piece of 1/2 inch PVC pipe (a bit larger than the faucet washers, but also required a few less turns). No, I don't know what effect the different dielectric constant of the PVC had on the result. 2) Many years ago I obtained some PCB material that is quite thin and flexible. My method for making the "pads" is to punch them out of this material with a conventional paper punch (the pliers shaped type you can buy for a couple of USD in many local stores). I sometimes punch out a handfull when I have a few free minutes (it makes a great distraction during those boring commercials on US Television), or if none are immediately available I will punch out just what I need as I build a circuit. At times I have made pads from thicker PCB material by just punching them out from PCB scrap(and from used boards when parts have all been removed) by using the larger lever-operated paper punch on my desk. Also, in the US Harbor Freight sells a compound-action pliers type punch (about $10 USD) complete with different sized dies, see <www.harborfreight.com> and search for "punch". FYI: My "pads" using the thin PCB material measure 1.4 PF between the circuit connection and underlying PCB substrata. I'm using "Super Glue" to stick them down. 3) Yes, when I am in a hurry, like assembling my first BITX20, I resort to point-to-point self-supported wiring...the UGLY method. It is quick and effective, but nearly impossible to repair if the defective part is two or three layers deep in the rats-nest of connections. 4) My initial BITX20 effort did not use the LM-386 AF amp. Instead I just used a 741 Op-Amp and relied on headphones-only for the audio output. I guess I neatly sidstepped the schematic error regarding the wrong pin being indicated for the + voltage! ;-) Since then I have added an NPN (2N3904) driving an NPN-PNP (2N3904 & 2N3906) pair for 1/2 watt of audio to the speaker. Maybe I am different but I see Farhan's elegant design as very interesting because it allows the builder to match up his particular incantation of the rig with the contents of his junk box. My BITX40 is coming along quite well. Several modules have been assembled and tested with just the IF filter, VFO, and the linear amp left to finish. I am waiting for an order to be delivered from "Dan's Small Parts" before I can continue. My junk box became severly depleted of the more commonly used parts! 73's Arv _._ |
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Re: IF amp pcb
John Fisher
¿ªÔÆÌåÓýVery nice PCB, I'm certainly enjoying these
photos :-) Thanks to all for your interesting posts :-) Being somewhat of a
photographer, I always say "One can never be too rich, too thin, or have too
much light" :-) But of course one can never have too many friends or too much
shielding :-) Thanks for the bandwidth :-)
?Regards, ?John ?
=============================================
email:????? k5jhf@... photos:??? files:??????? webpage:? callsign:??? K5JHF =============================================
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IF amp pcb
vk3bfa
Hello Fello wBuilders,
think I stuffed up a previous message post - anyway, have posted a photo of my humble efforts at kitchen sink PCB making for the BITX20 IF Amp - its in the VK3BFA folder. Any comments on probable mistakes welcome - will try and load it with components tomorrow if I can ignore customer jobs already on the work bench hi hi. I build on the track side of the PCB (semi ugly/manhattan) - so much easier to troubleshoot..... 73 de VK3BFA Andrew |
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Re: Please suggest for alternative 'linear amplifier module'
Jim Strohm
On Jun 26, 2004, at 11:03 PM, MILAREPA wrote:
Dear forum,Both those circuits will work fine, as will most any other QRP amp circuit. A broadbanded circuit is easier to build and use because it requires no tune-up and is less likely to have a parasitic oscillation. Be aware that those two amps NEED a low-pass output filter. For 20M, the BITX20 filter will be fine. For other frequencies, most popular radio handbooks have equations and design examples for the frequency of interest. Readers are reminded that Harry SM0VPO likes to share his work, but doesn't like seeing others pirate it or claim it as their own. So be sure to provide attribution (as was done here) when you share his stuff. He has the best homebrew radio site in the world, and we'd like to encourage him to keep it online, by respecting his work and his copyright. Jim N6OTQ |
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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
¿ªÔÆÌåÓýHi
?
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
¿ªÔÆÌåÓýDear 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
¿ªÔÆÌåÓýHi 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
¿ªÔÆÌåÓýMark
& 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
¿ªÔÆÌåÓýBruce
?
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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