Topics

BitX 20 Build: Nylon washer or toroid #bitx20

Aaron K5ATG
 

I'm starting a homebrew BITX 20 build, I guess from Ashhar's original design
BITX - An easy to build 6 watts SSB transceiver for 14MHz
I was just wondering if anyone else has built this and if you went with the schematics and used nylon tap washers or went with actual toroids. 

MVS Sarma
 

Aaron, 
Greetings from India. 
Those were times when getting toroid is little tough. 
Why noy ww use t50-6 , T37-6 for tuned circuits and FT37-43 and FT50-43 for transformers !!!

Regards
Sarma vu3zmv

On Sat, 6 Jun 2020, 8:05 am Aaron K5ATG via groups.io, <k5atg=yahoo.com@groups.io> wrote:
I'm starting a homebrew BITX 20 build, I guess from Ashhar's original design
BITX - An easy to build 6 watts SSB transceiver for 14MHz
I was just wondering if anyone else has built this and if you went with the schematics and used nylon tap washers or went with actual toroids. 

Arv Evans
 

Aaron

That original design is from over 10 years ago.  There were several hundred built and used on the air.  Some are still in use.  
Tap washers were used for a couple of years before an article by Wes Hayward suggested that toroids might be superior to tap washers.  His concern was that the apparent Q-factor was lower than that of toroids.  
The original design used 2N2222 devices until it was found that 2N2222 from Radio Shack were not cosistently good quality.  As a result most subsequent rigs used 2N3904 devices from Digikey.  

Arv. K7HKL
_-_


On Fri, Jun 5, 2020, 8:35 PM Aaron K5ATG via groups.io <k5atg=yahoo.com@groups.io> wrote:
I'm starting a homebrew BITX 20 build, I guess from Ashhar's original design
BITX - An easy to build 6 watts SSB transceiver for 14MHz
I was just wondering if anyone else has built this and if you went with the schematics and used nylon tap washers or went with actual toroids. 

Ashhar Farhan
 

That design is actually 17 years old. In these 17 years I discovered that teflon washers (take a 1/2" teflon rod, slice it into 1/4" disks and drill 1/4" hole through each disc) give far better performance than even the Amidon/Micrometal toroids do.
Nylon ones are quite lossy.
- f


On Sat 6 Jun, 2020, 11:28 AM Arv Evans, <arvid.evans@...> wrote:
Aaron

That original design is from over 10 years ago.  There were several hundred built and used on the air.  Some are still in use.  
Tap washers were used for a couple of years before an article by Wes Hayward suggested that toroids might be superior to tap washers.  His concern was that the apparent Q-factor was lower than that of toroids.  
The original design used 2N2222 devices until it was found that 2N2222 from Radio Shack were not cosistently good quality.  As a result most subsequent rigs used 2N3904 devices from Digikey.  

Arv. K7HKL
_-_


On Fri, Jun 5, 2020, 8:35 PM Aaron K5ATG via groups.io <k5atg=yahoo.com@groups.io> wrote:
I'm starting a homebrew BITX 20 build, I guess from Ashhar's original design
BITX - An easy to build 6 watts SSB transceiver for 14MHz
I was just wondering if anyone else has built this and if you went with the schematics and used nylon tap washers or went with actual toroids. 

 

Farhan,

I have some Teflon toroids, dont remember where and in what junk I got them. When in the future we meet I will
show you or if I get to town will dig up some and send you!

Raj


At 06/06/2020, you wrote:
That design is actually 17 years old. In these 17 years I discovered that teflon washers (take a 1/2" teflon rod, slice it into 1/4" disks and drill 1/4" hole through each disc) give far better performance than even the Amidon/Micrometal toroids do.
Nylon ones are quite lossy.
- f

On Sat 6 Jun, 2020, 11:28 AM Arv Evans, <arvid.evans@...> wrote:
Aaron

That original design is from over 10 years ago.  There were several hundred built and used on the air.  Some are still in use. Â
Tap washers were used for a couple of years before an article by Wes Hayward suggested that toroids might be superior to tap washers.  His concern was that the apparent Q-factor was lower than that of toroids. Â
The original design used 2N2222 devices until it was found that 2N2222 from Radio Shack were not cosistently good quality.  As a result most subsequent rigs used 2N3904 devices from Digikey. Â

Arv. K7HKL
_-_


On Fri, Jun 5, 2020, 8:35 PM Aaron K5ATG via groups.io <k5atg=yahoo.com@groups.io > wrote:
I'm starting a homebrew BITX 20 build, I guess from Ashhar's original design
BITX - An easy to build 6 watts SSB transceiver for 14MHz
I was just wondering if anyone else has built this and if you went with the schematics and used nylon tap washers or went with actual toroids. 

Ashhar Farhan
 

Thanks Raj,
I sawed off a few last year. That investigation had the misfortune of being the last thread on emrfd group.
- f

On Sat 6 Jun, 2020, 1:31 PM Raj vu2zap, <rajendrakumargg@...> wrote:
Farhan,

I have some Teflon toroids, dont remember where and in what junk I got them. When in the future we meet I will
show you or if I get to town will dig up some and send you!

Raj


At 06/06/2020, you wrote:
That design is actually 17 years old. In these 17 years I discovered that teflon washers (take a 1/2" teflon rod, slice it into 1/4" disks and drill 1/4" hole through each disc) give far better performance than even the Amidon/Micrometal toroids do.
Nylon ones are quite lossy.
- f

On Sat 6 Jun, 2020, 11:28 AM Arv Evans, <arvid.evans@...> wrote:
Aaron

That original design is from over 10 years ago.  There were several hundred built and used on the air.  Some are still in use. Â
Tap washers were used for a couple of years before an article by Wes Hayward suggested that toroids might be superior to tap washers.  His concern was that the apparent Q-factor was lower than that of toroids. Â
The original design used 2N2222 devices until it was found that 2N2222 from Radio Shack were not cosistently good quality.  As a result most subsequent rigs used 2N3904 devices from Digikey. Â

Arv. K7HKL
_-_


On Fri, Jun 5, 2020, 8:35 PM Aaron K5ATG via groups.io <k5atg=yahoo.com@groups.io > wrote:
I'm starting a homebrew BITX 20 build, I guess from Ashhar's original design
BITX - An easy to build 6 watts SSB transceiver for 14MHz
I was just wondering if anyone else has built this and if you went with the schematics and used nylon tap washers or went with actual toroids. 

Arv Evans
 

Farhan & Raj

Here in the US we can purchase small diameter nylon plumbing pipe ( PECC pipe).  Problem is that it comes in 50 or 100 foot rolls.  A local plumber should have scraps in short lengths.  It is not expensive, may even be FREE in scrap lengths. 

ID diameters in 3/8 inch or larger can be cut to any length you might need as either toroidal or solenoid inductor forms.  

Arv
_-_



On Sat, Jun 6, 2020, 11:40 AM Ashhar Farhan <farhanbox@...> wrote:
Thanks Raj,
I sawed off a few last year. That investigation had the misfortune of being the last thread on emrfd group.
- f

On Sat 6 Jun, 2020, 1:31 PM Raj vu2zap, <rajendrakumargg@...> wrote:
Farhan,

I have some Teflon toroids, dont remember where and in what junk I got them. When in the future we meet I will
show you or if I get to town will dig up some and send you!

Raj


At 06/06/2020, you wrote:
That design is actually 17 years old. In these 17 years I discovered that teflon washers (take a 1/2" teflon rod, slice it into 1/4" disks and drill 1/4" hole through each disc) give far better performance than even the Amidon/Micrometal toroids do.
Nylon ones are quite lossy.
- f

On Sat 6 Jun, 2020, 11:28 AM Arv Evans, <arvid.evans@...> wrote:
Aaron

That original design is from over 10 years ago.  There were several hundred built and used on the air.  Some are still in use. Â
Tap washers were used for a couple of years before an article by Wes Hayward suggested that toroids might be superior to tap washers.  His concern was that the apparent Q-factor was lower than that of toroids. Â
The original design used 2N2222 devices until it was found that 2N2222 from Radio Shack were not cosistently good quality.  As a result most subsequent rigs used 2N3904 devices from Digikey. Â

Arv. K7HKL
_-_


On Fri, Jun 5, 2020, 8:35 PM Aaron K5ATG via groups.io <k5atg=yahoo.com@groups.io > wrote:
I'm starting a homebrew BITX 20 build, I guess from Ashhar's original design
BITX - An easy to build 6 watts SSB transceiver for 14MHz
I was just wondering if anyone else has built this and if you went with the schematics and used nylon tap washers or went with actual toroids. 

Alex
 

FWIW, Home Depot sells PECC in shorter lengths of 3 or 4 feet as
individual pieces in 1/2" and 3/4" sizes

wd2t

On Sat, Jun 6, 2020 at 2:10 PM Arv Evans <arvid.evans@...> wrote:

Farhan & Raj

Here in the US we can purchase small diameter nylon plumbing pipe ( PECC pipe). Problem is that it comes in 50 or 100 foot rolls. A local plumber should have scraps in short lengths. It is not expensive, may even be FREE in scrap lengths.

ID diameters in 3/8 inch or larger can be cut to any length you might need as either toroidal or solenoid inductor forms.

Arv
_-_



On Sat, Jun 6, 2020, 11:40 AM Ashhar Farhan <farhanbox@...> wrote:

Thanks Raj,
I sawed off a few last year. That investigation had the misfortune of being the last thread on emrfd group.
- f

On Sat 6 Jun, 2020, 1:31 PM Raj vu2zap, <@Raj> wrote:

Farhan,

I have some Teflon toroids, dont remember where and in what junk I got them. When in the future we meet I will
show you or if I get to town will dig up some and send you!

Raj


At 06/06/2020, you wrote:

That design is actually 17 years old. In these 17 years I discovered that teflon washers (take a 1/2" teflon rod, slice it into 1/4" disks and drill 1/4" hole through each disc) give far better performance than even the Amidon/Micrometal toroids do.
Nylon ones are quite lossy.
- f

On Sat 6 Jun, 2020, 11:28 AM Arv Evans, <arvid.evans@...> wrote:
Aaron

That original design is from over 10 years ago. There were several hundred built and used on the air. Some are still in use. Â
Tap washers were used for a couple of years before an article by Wes Hayward suggested that toroids might be superior to tap washers. His concern was that the apparent Q-factor was lower than that of toroids. Â
The original design used 2N2222 devices until it was found that 2N2222 from Radio Shack were not cosistently good quality. As a result most subsequent rigs used 2N3904 devices from Digikey. Â

Arv. K7HKL
_-_


On Fri, Jun 5, 2020, 8:35 PM Aaron K5ATG via groups.io <k5atg=yahoo.com@groups.io > wrote:
I'm starting a homebrew BITX 20 build, I guess from Ashhar's original design
BITX - An easy to build 6 watts SSB transceiver for 14MHz
I was just wondering if anyone else has built this and if you went with the schematics and used nylon tap washers or went with actual toroids.Â

Ashhar Farhan
 

The toroid cant be too thin. What is the size of thr inner and outer diameters?


On Sun 7 Jun, 2020, 12:21 AM Alex, <abmurphy2011@...> wrote:
FWIW, Home Depot sells PECC in shorter lengths of 3 or 4 feet as
individual pieces in 1/2" and 3/4" sizes

wd2t

On Sat, Jun 6, 2020 at 2:10 PM Arv Evans <arvid.evans@...> wrote:
>
> Farhan & Raj
>
> Here in the US we can purchase small diameter nylon plumbing pipe ( PECC pipe).  Problem is that it comes in 50 or 100 foot rolls.  A local plumber should have scraps in short lengths.  It is not expensive, may even be FREE in scrap lengths.
>
> ID diameters in 3/8 inch or larger can be cut to any length you might need as either toroidal or solenoid inductor forms.
>
> Arv
> _-_
>
>
>
> On Sat, Jun 6, 2020, 11:40 AM Ashhar Farhan <farhanbox@...> wrote:
>>
>> Thanks Raj,
>> I sawed off a few last year. That investigation had the misfortune of being the last thread on emrfd group.
>> - f
>>
>> On Sat 6 Jun, 2020, 1:31 PM Raj vu2zap, <rajendrakumargg@...> wrote:
>>>
>>> Farhan,
>>>
>>> I have some Teflon toroids, dont remember where and in what junk I got them. When in the future we meet I will
>>> show you or if I get to town will dig up some and send you!
>>>
>>> Raj
>>>
>>>
>>> At 06/06/2020, you wrote:
>>>
>>> That design is actually 17 years old. In these 17 years I discovered that teflon washers (take a 1/2" teflon rod, slice it into 1/4" disks and drill 1/4" hole through each disc) give far better performance than even the Amidon/Micrometal toroids do.
>>> Nylon ones are quite lossy.
>>> - f
>>>
>>> On Sat 6 Jun, 2020, 11:28 AM Arv Evans, <arvid.evans@...> wrote:
>>> Aaron
>>>
>>> That original design is from over 10 years ago.  There were several hundred built and used on the air.  Some are still in use. Â
>>> Tap washers were used for a couple of years before an article by Wes Hayward suggested that toroids might be superior to tap washers.  His concern was that the apparent Q-factor was lower than that of toroids. Â
>>> The original design used 2N2222 devices until it was found that 2N2222 from Radio Shack were not cosistently good quality.  As a result most subsequent rigs used 2N3904 devices from Digikey. Â
>>>
>>> Arv. K7HKL
>>> _-_
>>>
>>>
>>> On Fri, Jun 5, 2020, 8:35 PM Aaron K5ATG via groups.io <k5atg=yahoo.com@groups.io > wrote:
>>> I'm starting a homebrew BITX 20 build, I guess from Ashhar's original design
>>> BITX - An easy to build 6 watts SSB transceiver for 14MHz
>>> I was just wondering if anyone else has built this and if you went with the schematics and used nylon tap washers or went with actual toroids.Â
>
>



Arv Evans
 

Farhan

Just measured some PECC and find the following:

3/8 inch nominal size = 0.492" OD, 0.377" ID, 0.069" wall thickness.
1/2 inch nominal size = 0.652" OD, 0.475" ID, 0.095" wall thickness.
3/4 inch nominal size = 0.870" OD, 0.677" ID, 0.109" wall thickness.

Yes, OD - ID is a bit off from measured wall thickness.  This is due to 
measurement error and manufacturing irregularities.

PECC pipe and PVC pipe is also available in short lengths as "basin
tube" used for connecting wash basins and sinks to the shut-off valve.  

It is possible to make the toroidal form longer.  This results in higher 
distributed capacitance per turn  as well as higher inductance.  This 
is interesting but I have not taken the time and effort to fully explore 
this phenomenon.  

Arv
_._


On Sat, Jun 6, 2020 at 1:33 PM Ashhar Farhan <farhanbox@...> wrote:
The toroid cant be too thin. What is the size of thr inner and outer diameters?

On Sun 7 Jun, 2020, 12:21 AM Alex, <abmurphy2011@...> wrote:
FWIW, Home Depot sells PECC in shorter lengths of 3 or 4 feet as
individual pieces in 1/2" and 3/4" sizes

wd2t

On Sat, Jun 6, 2020 at 2:10 PM Arv Evans <arvid.evans@...> wrote:
>
> Farhan & Raj
>
> Here in the US we can purchase small diameter nylon plumbing pipe ( PECC pipe).  Problem is that it comes in 50 or 100 foot rolls.  A local plumber should have scraps in short lengths.  It is not expensive, may even be FREE in scrap lengths.
>
> ID diameters in 3/8 inch or larger can be cut to any length you might need as either toroidal or solenoid inductor forms.
>
> Arv
> _-_
>
>
>
> On Sat, Jun 6, 2020, 11:40 AM Ashhar Farhan <farhanbox@...> wrote:
>>
>> Thanks Raj,
>> I sawed off a few last year. That investigation had the misfortune of being the last thread on emrfd group.
>> - f
>>
>> On Sat 6 Jun, 2020, 1:31 PM Raj vu2zap, <rajendrakumargg@...> wrote:
>>>
>>> Farhan,
>>>
>>> I have some Teflon toroids, dont remember where and in what junk I got them. When in the future we meet I will
>>> show you or if I get to town will dig up some and send you!
>>>
>>> Raj
>>>
>>>
>>> At 06/06/2020, you wrote:
>>>
>>> That design is actually 17 years old. In these 17 years I discovered that teflon washers (take a 1/2" teflon rod, slice it into 1/4" disks and drill 1/4" hole through each disc) give far better performance than even the Amidon/Micrometal toroids do.
>>> Nylon ones are quite lossy.
>>> - f
>>>
>>> On Sat 6 Jun, 2020, 11:28 AM Arv Evans, <arvid.evans@...> wrote:
>>> Aaron
>>>
>>> That original design is from over 10 years ago.  There were several hundred built and used on the air.  Some are still in use. Â
>>> Tap washers were used for a couple of years before an article by Wes Hayward suggested that toroids might be superior to tap washers.  His concern was that the apparent Q-factor was lower than that of toroids. Â
>>> The original design used 2N2222 devices until it was found that 2N2222 from Radio Shack were not cosistently good quality.  As a result most subsequent rigs used 2N3904 devices from Digikey. Â
>>>
>>> Arv. K7HKL
>>> _-_
>>>
>>>
>>> On Fri, Jun 5, 2020, 8:35 PM Aaron K5ATG via groups.io <k5atg=yahoo.com@groups.io > wrote:
>>> I'm starting a homebrew BITX 20 build, I guess from Ashhar's original design
>>> BITX - An easy to build 6 watts SSB transceiver for 14MHz
>>> I was just wondering if anyone else has built this and if you went with the schematics and used nylon tap washers or went with actual toroids.Â
>
>



ohwenzelph
 

Where do you get 1/2” Teflon rod? What do they use it for? “far better performance than even the Amidon/Micrometal toroids” sounds pretty good to me.

Arv Evans
 


On Sat, Jun 6, 2020 at 3:54 PM ohwenzelph via groups.io <Ohwenzelph=yahoo.com@groups.io> wrote:
Where do you get 1/2” Teflon rod? What do they use it for? “far better performance than even the Amidon/Micrometal toroids” sounds pretty good to me.

Dale Parfitt
 

Polyethylene tubing is as good as teflon from a loss standpoint and is available at the big box stores.  It is hard for me to believe though that an inductor wound  on a plastic toroid core  is going to be better than one wound on a powdered iron core- particularly when a  lot of turns are required. The self resonant frequency is going to be lower (higher self capacitance) and I squared R losses (more turns required) may well make it a lower Q inductor  than the powdered iron.

An easy experiment on a vector network analyzer.

 

Dale W4OP

 

From: BITX20@groups.io [mailto:BITX20@groups.io] On Behalf Of ohwenzelph via groups.io
Sent: Saturday, June 6, 2020 5:54 PM
To: BITX20@groups.io
Subject: Re: [BITX20] BitX 20 Build: Nylon washer or toroid #bitx20

 

Where do you get 1/2” Teflon rod? What do they use it for? “far better performance than even the Amidon/Micrometal toroids” sounds pretty good to me.

Bob Lunsford
 

Try TAP Plastics. There are several in Sacramento, CA and it's not a local-only outlet for such things.

KK5R

On Saturday, June 6, 2020, 5:54:24 PM EDT, ohwenzelph via groups.io <ohwenzelph@...> wrote:


Where do you get 1/2” Teflon rod? What do they use it for? “far better performance than even the Amidon/Micrometal toroids” sounds pretty good to me.

Curt
 

Aaron

There are affordable toroid sources in the states, and from just dash 2, 6, 43 and maybe 61 you can make lots of inductors and transformers. See if w8diz partsandkits.com is still in business.

Curt wb8yyy

 

Hi,

Looking back at Farhan's last EMRD Yahoo group thread, he was using a teflon core at VHF 60MHz for a bandpass filter.  This makes sense.  But that's a big difference from doing that for inductors at HF and a huge difference from doing that for transformers at HF.

Making inductors for use at different frequencies using different cores and forms has been studied for decades, there is a great store of knowledge and experience; that is why we have available optimal core materials for the frequency range, use, and inductor size that we want.  As a note: this knowledge shows that as frequency goes up, for inductors you need/want a core with lower permiability the higher you go.  That is why when you start to hit the VHF and higher range, phenolic/plastic materials or air cores are recommended.  An example is "type 0" core material which is phenolic (quoted from toroids.info):

Optimum Resonant Circuit Range
for highest Q and lowest core loss
50 MHz - 350 MHz

So teflon makes sense at VHF for sure, but not so much at HF -- unless you want to make physically larger inductors.  Ferric materials increase Q of physically small inductors; you can make high Q inductors for HF without them, but then they need to be much larger in size (and will need shielding too).

73,


Mark




Ashhar Farhan
 

Mark, 
The nylon/teflon toroids were never meant for broadband work. We are only discussing them for bandpass and low pass filters. Given that they don't have any measurable core saturation, they are quite useful in power amp outputs, antenna tuners, etc. 
However, for broadband work, you will still need to ferrite cores, baluns and toroids.
Narrow band is easier with teflon/air/nylon toroids.
By the way, there is an easy way to know if a household material will do as a toroid former. Microwave it and see. If it gets hot, it absorbs the emf. Hans discovered this hack.
- f

On Sun 7 Jun, 2020, 8:36 AM Mark - N7EKU, <n7eku@...> wrote:
Hi,

Looking back at Farhan's last EMRD Yahoo group thread, he was using a teflon core at VHF 60MHz for a bandpass filter.  This makes sense.  But that's a big difference from doing that for inductors at HF and a huge difference from doing that for transformers at HF.

Making inductors for use at different frequencies using different cores and forms has been studied for decades, there is a great store of knowledge and experience; that is why we have available optimal core materials for the frequency range, use, and inductor size that we want.  As a note: this knowledge shows that as frequency goes up, for inductors you need/want a core with lower permiability the higher you go.  That is why when you start to hit the VHF and higher range, phenolic/plastic materials or air cores are recommended.  An example is "type 0" core material which is phenolic (quoted from toroids.info):

Optimum Resonant Circuit Range
for highest Q and lowest core loss
50 MHz - 350 MHz

So teflon makes sense at VHF for sure, but not so much at HF -- unless you want to make physically larger inductors.  Ferric materials increase Q of physically small inductors; you can make high Q inductors for HF without them, but then they need to be much larger in size (and will need shielding too).

73,


Mark




n5ib_2
 

How many folks remember the old trick (not invented by me) for making an air-core toroidal inductor:

Wind your coil on a Lifesaver candy (I/m partial to the wintergreen mint). That's about the size of a T68 core. Wire gauge needs to be large enough to hold its shape. When wound, and **after** the leads have been trimmed and tinned, dunk the whole affair into boiling water. Candy dissolves, coil remains. It'll spring out a bit, but basically keeps its shape.

N5IB

Don--AE4DW
 

On Sat, Jun 6, 2020 at 09:43 PM, Curt wrote:
Aaron

There are affordable toroid sources in the states, and from just dash 2, 6, 43 and maybe 61 you can make lots of inductors and transformers. See if w8diz partsandkits.com is still in business.

Curt wb8yyy

I just received a shipment from Diz on Friday, he is most definitely in business. The url is actually https://kitsandparts.com/ , the usual good prices and fast service.

N6QWHAM@...
 

Hi Aaron,

I built the Bitx20 shortly after it was unveiled to the world and as it is now, it was then -- a solid design. The see how robust a design it was I used transistor sockets on all of the lower level stages and I cycled various transistors into the sockets --including a bag of obsolete 2N706 early on RF transistors. Even they worked except for one stage --the BFO where you had to cherry pick one that would consistently oscillate. Others that were tried include the 2N2222 and even a grab bag of no name NPN transistors. So that says much about a design that can take generic transistors and still work

There were several changes I made including not using the Teflon washers and I even shared the winding data for FT-37-43 cores. Several other changes included moving the IF to 9 MHz and adding the EI9GQ VFO stabilizer to keep the frequency locked. So homebrewing a Bitx 20 is indeed a viable approach. My call at that time was W6JFR. A special note --the main board is NOT perf board but instead a piece of single sided copper PC Board that was hand drilled using a perf board overlay. The continuous copper ground plane makes this work!

73's
Pete N6QW

approach