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Hi fellow BITX-homebrewer,
Yesterday I was browsing through some old "Electrons" (Dutch Ham
magazine) and found an interesting article in which it was told that
our famous MOSFET IRF-family (in particular IRF510 and IRF540) could
work on 50 MHz ! I am surprised by this. The article did not show
fixed designs, so maybe it is just wishfull thinking...
According to the article, achievable power levels should less lower
than at, let's say 7 MHz ( 2 Watts versus 12 Watts RF).
Anybody experience in this field ?

Interesting idea, by the way, to make the BITX useable for 6m.

However, with an IF of 10MHz, VFO freq of 40MHz might be too high to
get a (simple) rock-stable VFO.

Since I do have ham equipment for 70 cm, 2m, HF but not for 6 m, this
might be another nice (winter) project.

Anybody ideas for homebrew 6m transceiver (50...52 MHz) on the www
according to the KISS principle (Keep It Simple Stupid) ??

73 de Ron
PA2RF

Hi Ron and all BITX'ers
You have have been reading my thoughts, my BITX20 is still
at the building stage due to an Open University course which
finishes in October. My thoughts were to use the basic
20metre transceiver without PA stage, feed this into an SBL-1
mixer with a 36MHz crystal oscillator. The output/input of
the mixer will be at 50MHz. This is then fed into a 50MHz PA
stage based on the existing design. This would give a
transceiver capable of working on 14 and 50MHZ.
72/73's
David G8EMA


David Pedley
Senior Medical Devices Librarian
Torbay Hospital
tel 01803-655873


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Hi Ron and all BITX'ers
? You have have been reading my thoughts, my BITX20 is still
at the building stage due to an Open University course which
finishes in October. My thoughts were to use the basic
20metre transceiver without PA stage, feed this into an SBL-1
mixer with a 36MHz crystal oscillator. The output/input of
the mixer will be at 50MHz. This is then fed into a 50MHz PA
stage based on the existing design. This would give a
transceiver capable of working on 14 and 50MHZ.
72/73's
David G8EMA
???

David Pedley
Senior Medical Devices Librarian
Torbay Hospital
tel 01803-655873


This e-mail is confidential and privileged. If you are not the intended
recipient please accept our apologies; please do not disclose, copy or
distribute information in this e-mail or take any action in reliance on its
contents: to do so is strictly prohibited and may be unlawful. Please
inform us that this message has gone astray before deleting it. Thank you
for your co-operation.

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Ron

The IRF510 device has an input capacitance of 180 pf, and an output
capacitance if 81 pf (from the International Rectifier product datasheet).
With this high input capacitance your 52 MHz driver stage impedance will have
to be very low. If you can drive this low impedance then it might be
possible.

But, there are other devices that could be used as the driver and output
stages with a high probability of success.

I wonder if anybody has cataloged all the bands for which BITX units have been
built? Obviously, 20M, 40M, 17M, and I think 30M have been done. Any
others?

Arv K7HKL
_._

Hello Ron,

There is a design for a 50W V-MOSFET Linear for 50MHz in Pat Hawkers, G3VA,
"Technical Topics 2000 - 2004", pages 32 - 33, which might be interesting
for you. This book is a collection of reprints of a monthly column in the
RSGB Radcom. This article was published in Radcom of July 2000.

The design goes back to a publication of Dieter Mergner, DJ9FG, originally
appearing in the German "Funkamateur" 12/1999 and 01/2000. It uses two
IRF610 in push-pull with a 50V power supply. I was surprised to see IRF
MOSFETS at 50MHz. Some years ago I have build some single ended as well as
push-pull designs myself, but I couldn't get a reasonable output above 14
MHz. I worked with a maximum supply voltage of 30V. I have a better power
supply now. So maybe I should try MOSFETS again...

The book of Pat Hawker is worth reading every line of it!

73 Heinz, OE5EEP

Am Mittwoch, 29. Juni 2005 12:10 schrieb Ron:

Indeed, there you have your RF input circuitry.
Not the output. Sinse BITX is a transceiver, the SBL solution looks
more relevant to me. In fact, you can build double balanced mixers
yourself like the ones in the current BITX20.
Regards,
Chris.

Have a look at and

look for the 6 m converter. Here is your RF input circuitry !

ON6MU has described this fb 50MHz mixer with the NE6...

Hi fellow BITX-homebrewer,
Yesterday I was browsing through some old "Electrons" (Dutch Ham
magazine) and found an interesting article in which it was told that
our famous MOSFET IRF-family (in particular IRF510 and IRF540) could
work on 50 MHz ! I am surprised by this. The article did not show
fixed designs, so maybe it is just wishfull thinking...
According to the article, achievable power levels should less lower
than at, let's say 7 MHz ( 2 Watts versus 12 Watts RF).
Anybody experience in this field ?

Interesting idea, by the way, to make the BITX useable for 6m.

However, with an IF of 10MHz, VFO freq of 40MHz might be too high to
get a (simple) rock-stable VFO.

Since I do have ham equipment for 70 cm, 2m, HF but not for 6 m, this
might be another nice (winter) project.

Anybody ideas for homebrew 6m transceiver (50...52 MHz) on the www
according to the KISS principle (Keep It Simple Stupid) ??

73 de Ron
PA2RF

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Tnx for your input Rahul,

Yes impressive. OK this proves IRF family MOSFET can be used on 6m.
(in spite of relative high input capacity of several pF)
This is non-QRP for sure!
Interesting URLs you supplied Rahul.
Bye
Ron


--- In BITX20@..., Rahul Srivastava <vu3wjm@y...> wrote:

Hi!

I had been interested in 6mtr and related equipment. Once again as

evident by BITX concept we had no 6mtr stuff available in VU. I was
much impressed with this 50mhz mega amp using IRF510.

Sorry this is no QRP stuff but just goes on to show what can be

achieved using common garden variety components.

In due course I also came across some design having very high IF ie

up conversion ie 40mhz range. Now with such high IFs it is simple
matter to to hook up a 6mtr equipment using conventional low freq VFO.

Most of the multiband design here can be tailored for 6mtr

operations.

Lately we had some serious discussions on using microwave and high

Ft devices I am sure getting onto 6 would be no problem.

73

Rahul VU3WJM







Ron <pa2rf@y...> wrote:
Hi fellow BITX-homebrewer,
Yesterday I was browsing through some old "Electrons" (Dutch Ham
magazine) and found an interesting article in which it was told

that

our famous MOSFET IRF-family (in particular IRF510 and IRF540)

could

work on 50 MHz ! I am surprised by this. The article did not show
fixed designs, so maybe it is just wishfull thinking...
According to the article, achievable power levels should less lower
than at, let's say 7 MHz ( 2 Watts versus 12 Watts RF).
Anybody experience in this field ?

Interesting idea, by the way, to make the BITX useable for 6m.

However, with an IF of 10MHz, VFO freq of 40MHz might be too high

to

get a (simple) rock-stable VFO.

Since I do have ham equipment for 70 cm, 2m, HF but not for 6 m,

this

might be another nice (winter) project.

Anybody ideas for homebrew 6m transceiver (50...52 MHz) on the www
according to the KISS principle (Keep It Simple Stupid) ??

73 de Ron
PA2RF




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Sure Chris,

SBL have a bi-directional nature.
Signetics NE612/602 not. Additional switching required! Or 2 times
NE6..?
Thanks for advice,
Ron

Dear Heinz,
I really appreciate your summurization of all those good sources!
Another proof that IRF (610) can be used on the 'magic' 6 m band.
Up till now I have noticed 6m PA-stages with multiple IRF's only, no
QRP (single IRF) 6m PAs. Maybe qty of MOSFET must be increased in
order to obtain a reasonable RF output because of reduced efficiency
at higher frequencies of IRF family (or just coincidence).
Bye for now, danke sch?n,
Ron
PA2RF


--- In BITX20@..., Heinz Schnait <oe5eep@q...> wrote:

Hello Ron,

There is a design for a 50W V-MOSFET Linear for 50MHz in Pat

Hawkers, G3VA,

"Technical Topics 2000 - 2004", pages 32 - 33, which might be

interesting

for you. This book is a collection of reprints of a monthly column

in the

RSGB Radcom. This article was published in Radcom of July 2000.

The design goes back to a publication of Dieter Mergner, DJ9FG,

originally

appearing in the German "Funkamateur" 12/1999 and 01/2000. It uses

two

IRF610 in push-pull with a 50V power supply. I was surprised to see

IRF

MOSFETS at 50MHz. Some years ago I have build some single ended as

well as

push-pull designs myself, but I couldn't get a reasonable output

above 14

MHz. I worked with a maximum supply voltage of 30V. I have a better

power

supply now. So maybe I should try MOSFETS again...

The book of Pat Hawker is worth reading every line of it!

73 Heinz, OE5EEP

Am Mittwoch, 29. Juni 2005 12:10 schrieb Ron:

Hi fellow BITX-homebrewer,
Yesterday I was browsing through some old "Electrons" (Dutch Ham
magazine) and found an interesting article in which it was told

that

our famous MOSFET IRF-family (in particular IRF510 and IRF540)

could

work on 50 MHz ! I am surprised by this. The article did not show
fixed designs, so maybe it is just wishfull thinking...
According to the article, achievable power levels should less

lower

than at, let's say 7 MHz ( 2 Watts versus 12 Watts RF).
Anybody experience in this field ?

Thanks for advice Arv,

As you can see in the forum, several designs have been realized using
IRF's in 6m PA stages (the ones I have seen up till now, only with
multiple IRFs). So I guess the problems caused by the 180 pF input
capacitance can be overcome.

Best regards, 73
Ron

By the way, I succesfully completed a BITX17 using MixW; some PSK31
qso's and RTTY QSO's.
Latest experiments with program MMTTY in FSK mode (not AFSK).
Modulation (FSK) direct onto the 18.100 MHz X-tal.


--- In BITX20@..., Arv Evans <arvevans@e...> wrote:

Ron

The IRF510 device has an input capacitance of 180 pf, and an output
capacitance if 81 pf (from the International Rectifier product

datasheet).

With this high input capacitance your 52 MHz driver stage impedance

will have

to be very low. If you can drive this low impedance then it might

be

possible.

But, there are other devices that could be used as the driver and

output

stages with a high probability of success.

I wonder if anybody has cataloged all the bands for which BITX

units have been

built? Obviously, 20M, 40M, 17M, and I think 30M have been done.

Any

others?

Arv K7HKL
_._
On Wednesday 29 June 2005 04:10 am, Ron wrote:

Hi fellow BITX-homebrewer,
Yesterday I was browsing through some old "Electrons" (Dutch Ham
magazine) and found an interesting article in which it was told

that

our famous MOSFET IRF-family (in particular IRF510 and IRF540)

could

work on 50 MHz ! I am surprised by this. The article did not show
fixed designs, so maybe it is just wishfull thinking...
According to the article, achievable power levels should less

lower

than at, let's say 7 MHz ( 2 Watts versus 12 Watts RF).
Anybody experience in this field ?

Interesting idea, by the way, to make the BITX useable for 6m.

However, with an IF of 10MHz, VFO freq of 40MHz might be too

high to

get a (simple) rock-stable VFO.

Since I do have ham equipment for 70 cm, 2m, HF but not for 6 m,

this

might be another nice (winter) project.

Anybody ideas for homebrew 6m transceiver (50...52 MHz) on the

www

according to the KISS principle (Keep It Simple Stupid) ??

73 de Ron
PA2RF




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?
?To unsubscribe from this group, send an email to:
?BITX20-unsubscribe@...
?
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Currently on UK's Ebay Auction site..

Item number: 7527490184
( lot of 10 ) International Rectifier IRF510's

Buy it now price is 4.95 GBP

hth someone..
Mike
--

Mike

As I sit here looking at the Jameco catalog <www.jameco.com> I see IRFxxx
devices listed as:

DEVICE EACH Q=10 Q=100 Q=1000
======= ====== ====== ====== ======
IRF510 $0.69 $0.59 $0.55 $0.49
IRF620 $0.45 $0.42 $0.35 $0.32

Of couorse this is in USD. This should help you decide if that Ebay listing
is a good deal. It really seems to depend on the shipping cost.

Arv K7HKL
_._

--- In BITX20@..., "Ron" <pa2rf@y...> wrote:

Hi fellow BITX-homebrewer,
Yesterday I was browsing through some old "Electrons" (Dutch Ham
magazine) and found an interesting article in which it was told that
our famous MOSFET IRF-family (in particular IRF510 and IRF540) could
work on 50 MHz ! I am surprised by this. The article did not show
fixed designs, so maybe it is just wishfull thinking...
According to the article, achievable power levels should less lower
than at, let's say 7 MHz ( 2 Watts versus 12 Watts RF).
Anybody experience in this field ?

To drive the input of the mosfet at 6M you will have to use very
different networks so the input capacitance can be absorbed into the
network. Same would have to be done for output. Major redesign
of the "linear module" is the result. I've tried the IRF510 and
friends and they can generate fair power at 6m but they are hard to
drive and not as stable. Devices like the 2SC1307, 2sc799, 2sc1970
and 2sc1971 are easier to use and fairly common (found in 27,mhz
US CB radios). Power out with those can be as high as 10W.

However, with an IF of 10MHz, VFO freq of 40MHz might be too high to
get a (simple) rock-stable VFO.

The easiest way to get a 40mhz VFO is to take a 4mhz VFO and mix it
with a 36mhz crystal and filter the result to 40mhz. then you get the
stability of 4mhz VFO and the required high frequency.

I'm doing it with whats called a sampling tracking PLL. Simpler
than a full digital PLL and somewhat less trouble with spurs and
sidebands. Tuning between the digital steps is by varying the VXO
used in the down conversion osc. It allows me to use older PLL
chips that have /n counter that only count to 255 or maybe 512.


Allison
KB1GMX

--- In BITX20@..., "Ron" wrote:
> Hi fellow BITX-homebrewer,
> Yesterday I was browsing through some old "Electrons" (Dutch Ham
> magazine) and found an interesting article in which it was told that
> our famous MOSFET IRF-family (in particular IRF510 and IRF540) could
> work on 50 MHz ! I am surprised by this. The article did not show
> fixed designs, so maybe it is just wishfull thinking...
> According to the article, achievable power levels should less lower
> than at, let's say 7 MHz ( 2 Watts versus 12 Watts RF).
> Anybody experience in this field ?

To drive the input of the mosfet at 6M you will have to use very
different networks so the input capacitance can be absorbed into the
network.? Same would have to be done for output.? Major redesign
of the "linear module" is the result.? I've tried the IRF510 and
friends and they can generate fair power at 6m but they are hard to
drive and not as stable.? Devices like the 2SC1307, 2sc799, 2sc1970
and 2sc1971 are easier to use and fairly common (found in 27,mhz
US CB radios). Power out with those can be as high as 10W.

> However, with an IF of 10MHz, VFO freq of 40MHz might be too high to
> get a (simple) rock-stable VFO.

The easiest way to get a 40mhz VFO is to take a 4mhz VFO and mix it
with a 36mhz crystal and filter the result to 40mhz.? then you get the
stability of 4mhz VFO and the required high frequency.

I'm doing it with whats called a sampling tracking PLL.?? Simpler
than a full digital PLL and somewhat less trouble with spurs and
sidebands. Tuning between the digital steps is by varying the VXO
used in the down conversion osc.? It allows me to use older PLL
chips that have /n counter that only count to 255 or maybe 512.


Allison
KB1GMX

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--- In BITX20@..., Ron Brink <pa2rf@y...> wrote:

Thanks for the good info dear Allison,

Yes, in the meantime I discovered MOSFET IRF's are not most

favourable candidates for a 6 m PA. The 2SC Japanes transistors are
more common and most likely much easier to use.

A line up of 2n4124, 2sc1970 and a pair of 2sc1971 will do
9-11W CW power at 12V nominal.

About the synthesizer circuitry, in the past I have used a divider

4059 in combination with a 4046.

If after the VFO a hi-speed divider (e.g. 74F74 or U256) is used you

can go up to the GHz range and have a rockstable vfo.

That is certainly one way to go. Another is to use the 4046 phse
comparator in a 1:1 tracking loop with the reference being a VFO in
the 1-4mhz range.

Myself I build PLLs using chips like the MM55104, MC145106 and
MSM5807. Most of these are designed for 10khz challening used in US
CB radio but are easy to apply, found in junk radios and CMOS.
My preferd chip is the MC145106. Using those in a loop has a
twist. The divide by N counter in most maxes at 255 (255*10khz is
only 2.55mhz). This would imply a limited ability to do PLL in
the 40mhz range however there are easy ways around it. The most
common is to mix the VCO with a local crystal osc (better yet a VXO)
and have the result end up on the 1-2mhz range for counting. Then
the /n counter set the channel step and if you use the VSO you
can get interpolation between 10khz channels. One the base design
is worked out (copied from CB rig) scaling to any LO is easy as the
loop is the same and only the VCO and VXO is moved to suit. If built
carfully with good shielding and ground plane the 10khz spurs should
be at least 70db down. Since noise is related to the /n value this
scheme tends to be cleaner than those using a VHF counter. The side
effect is tuning range is limited to /n in the range of 10 to 255
or about 2.4mhz. I've built several using those chips and I package
them in a box of PCB material around 1.75" square and about .75" tall.
usual power consumed is under 60ma @5v. I have one I've built already
for upcomming Bitx-6.

Oh for tuning the pll without a micro. Take a 27c256 or similar
Eprom and program is so the address lines take 2 or 3 BCD coded
switches and translate that to a binary code at the output to suit.
The processis static and requires no clock (no cpu noise!) and is low
power.

My bitx-6 is progressing well. One of the design goals is to fit
it in a box 5Wx2Hx7D (inches) without headset, mic and DC power.
power ouput goal is in the 3-5W (cw power) range using 2SC1971.


Allison
KB1GMX