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Hello,

First the transistor used. The 2n222a or 2n3904 are excellent for
this type VFO.

I have tried to understand what problem you are having. I suspect
the range of tuning 0-230khz is either too small or too great for
you. The ability to adjust the frequency using the trimmer says
the coil and other components are close.

Allison
KB1GMX


--- In BITX20@..., kumar gautam <fromgautam@y...>

hi,
in my bitx20 vfo frequency is 4.000 to 4.230MHz or trimming the

trimmer i found 4.200 to 4.430 (i.e 0 to 0.230 MHz tuning range).
aftyer several changing in coil and various types of capacitor(2j

2x type) i coul'd not achive the desired frequency. i used 2n2222a
transistors for VFO and BFO and for rest 2n3904.

kindly anyone help me in this regard
with 73's
de kumar gautam


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hi,
in my bitx20 vfo frequency is 4.000 to 4.230MHz or trimming the

kindly anyone help me in this regard
with 73's
de kumar gautam


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HI,

HERE IN?MARKET IRF510 IS NOT AVAILABLE, ONLY IRF540 IS AVAILABLE. ANY ONE HELP ME THAT IRF540 IS EQUIVALENT OF IRF510 OR I CAN SUBSTITUTE THIS FET.

WITH 73'S

DE KUMAR GAUTAM

---

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Apologies list, for the bandwidth - I am having some trouble emailing
Allison on private email. Seems I am blocked somewhere :-(

73 Hans G0UPL


-----Original Message-----
From: Hans Summers
Sent: 22 July 2005 15:40
To: 'Allison'
Subject: RE: [BITX20] Re: IRF510 on higher voltage?



Hello Allison

I love Huff & Puff. These days DDS is so easy, but H&P is still

suitable for many people with no microcontroller etc skills. Though

a microcontroller-less DDS:

Thanks for the advice. I actually have been planning to build a

for quite a while. I have accumulated more than sufficient number of

PL509 TV sweep valves - there are several designs on the internet

for 400+ W using four PL509/519's paralleled. Very cheap and

I am lacking is the HT transformer. I quite liked Arv's idea of a solid
state linear because the PSU is there, all ready and waiting and

Thanks for the links, I had a good look around. You're right, it doesn't
look very cheap. The very real possibility of frying the transistors

the idea even more expensive. From what I hear, those PL5xx sweep

virtually indestructible, even if you make them practically red hot.

All of my ham stuff to date has been at 10W or below. See my TX and

I had my first ever QSO in March 2002 (a mere 8 years after getting my
license!). I've had over 500 QSO's now, all using that 1-valve crystal
controlled CW transmitter. Mostly on 80m, but also on 40 and 30 once I'd
converted the transmitter for those bands.

I'm not a committed QRP'er, I like to operate QRP but I'm not averse

either, just so long as it's homebrew. I've never touched a

and gonna keep it that way!

I did make a 2m AM handheld see
- it's not

some trouble with the crystal oscillator multipliers. Needs a bit

Tnx again for the advice and links.

73 de QTH nr London, UK
Hans G0UPL

-----Original Message-----
From: Allison [mailto:ajp166@b...]
Sent: 22 July 2005 13:30
To: Hans Summers
Subject: Re: [BITX20] Re: IRF510 on higher voltage?


Hans Summers wrote:

Hi Allison

I am moderator of the BITX20 and have been following your postings
with interest. I have a partially built BITX20 awaiting a little
debugging and perhaps some of the mods. Unfortunately very little

to work on it at the moment. The pictures are in the G0UPL folder on
the group page.

Hello Hans,

I have built and experimented with you milimal H&P circuits. Good

I was thinking of using this PSU with switching, as a variable
medium-high voltage supply for whatever I needed it for - but Arv
K7HKL (who you'll know from the BITX group) suggested, why not

into a solid state linear? 50V should suit MOSFET's quite well for
400W and the current capability more than adequate. I have attached a
couple of (poor quality) photos of this monster PSU. You'll see that
the it's divided into two compartments, the top contains just the
choke and three capacitors. It should be possible for me to move

caps elsewhere which would leave quite a lot of space, I think enough
for the linear. I could bolt on four aluminium panels, one of

function as front panel for metering, low pass filter switching, etc.

Opinion, doing that would represent the hard way with limited success.

To get to 400W is a significant endevor and trying with unknown RF
performance power fets is likely failure prone. All of the 100W or

designs for RF power use known RF transistors (bipolar or fet) that are
expensive (.5-2$/watt US). Most of the high voltage switching FETs

enough to operate at RF but Miller capcitance and input capacitance
will make themm very hard to drive at HF especially 10M.

I may add that the IMD performace for IRF510 and friends is terrible and
that translates to RF polution. They were not developed for linear
service, they were intended as power switches. The other thing is the
TO220 tab cases have poor thermal dissapation. That makes getting
thermal stability hard.

IF you were into AM phone, it's possible to use switching fets in a
class E design (Not FOR SSB). There are several here doing that with
power to 1.5KW. There are websites that discuss this.

Now, if you really still up for the idea.. Heres a possible path to

Expect to use parallel devices (seperate bias for each device) in push
pull configuration. You will need to accomodate the very high
(800-2000pF) input capacitance and low impedences involved. Expect
elaborate groundplanes and input/output transformers with quality
ferrite. A design of four IRF510s in pushpull (pairs of parallel
devices in pushpull) might get you to 80-100W at 24V or about 1Sunit

from 400W. Generally parallel devices are touchy and each has to
be biased independent of others.

So, I wondered what you thought of this crazy idea, and can you
suggest any web references on solid state linears at this power? I

some googling but didn't manage to find anything particularly
applicable. I have heard that Motorola might have some good App notes
about this.

Yes they do but, not for common HEXfets or other low cost power fets.
DEVICES like MRF140 and the like are used and they are not inexpensive.
Typical Vdd for these parts is in the 50V region (at up to 20A!).

Start with this site:

Comm Concepts sells kits for power amps based on Mototrola app notes.
Browse the site for examples, schematics and some of the apnotes.

can find some of the appnotes on the net. However, none
specify low cost fets and likely would not support low cost power fets.

Also, what is your opinion about valve vs solid state? It seems
strange that such a large number of linears are still valve based?
Even the newest models.

Simple, valve designs using obtainable valves are fairly straight

well documented. A 3-500 or 4-400 in grounded grid with 2000V on
the plate will easily hit 400W for 80-10m. A pair of 811/572B are in
the same league as well as a long list of other Valves that maybe had
used or surplus.

Why Valves(tubes)? They are known, durable within experience of most
hams and often can be had inexpensively. When you consider a 3-500Z can
often be had new for around 150$us and MRF150(x4) will cost 200$us

FETs may destruct on power up it's not too hard to visualize.

This outfit sells RF power transistors and other items like

While I've done commercial work at high power I choose to do most of
the ham activity at under 20W. My unusual twist on that is my station
while low powered is supported off of solar pannels and batteries. I

that I prefer VHF and up for my experiements.


Regards,
Allison
KB1GMX

Hi Kumar,

The datasheets give the following parameters:

IRF510: RDS = 0.54 Ohms; ID(continous) = 5.6 A; maxPower = 43W; Input
capacitance = 180 pF
IRF540: RDS = 0.077 Ohms; ID(continous) = 28A; max Power = 150W; Input
capacitance = 1700 pF

The IRF540 is a more robust version than the IRF510. It looks to me

the 540 has more junctions wired internally in parallel. This is also
reflected in the input capacitance, which is much higher for the

afraid this might cause problems for the gate driving circuit,

at higher frequencies.

Is anybody out there with a working IRF510 amp who would like to do

experiments with a IRF540 replacement? Please share your results!

73 Heinz, OE5EEP

Am Freitag, 22. Juli 2005 07:33 schrieb kumar gautam:

HI,
HERE IN MARKET IRF510 IS NOT AVAILABLE, ONLY IRF540 IS AVAILABLE. ANY
ONE HELP ME THAT IRF540 IS EQUIVALENT OF IRF510 OR I CAN

FET. WITH 73'S
DE KUMAR GAUTAM

Allison

That URL for the MOSFET HF Amp is actually:

I wonder if anyone has ever tried a grounded-gate MOSFET

much like the grounded-grid valve type amps? I have no idea if it

work, but it could be fun to try.

Hi Julius,
that is the fun, nothing to adjust in advance, just connect it (I
used two resistors as a signal attunuator)and watch the screen (if
you receive enough noise).
If you do not receive enough noise, you can choose that the peak is
hold, slowly tune over a carrier (can be anything, no requirements
about stability or so)and see the graph.
In fact, using this tool makes it easy to see if the BFO frequency
is correct. If you just click the link in 'Links, software' or

on you can see many samples
and an easy explenation.
(If you do not want to connect it and first want to see how it
works, you can use your microphone and hold it in front of the
speaker).
Please keep us informed about the results.
Thanks in advance,
Chris.

--- In BITX20@..., "Wijaya, J." <iyung_w@y...> wrote:

With the software and connecting the output of the AF amp to PC,

i wonder where do we set the BFO to find out the shape of our
filter, assuming that we do not know the center frequency yet, or
setting the BFO is not necessary?

rgds
julius

In German Funkamateur was published schematic for hf noise

and described metod of mesurment by using sondcard lf spectogram. I
am sorry that it is again in russian but can be easily translated.

couldnt find similar article in english. Schematics are
understandable on its own.




--- In BITX20@..., "vdberghak" <vdberghak@z...> wrote:

Indeed measuring is knowing if the final result is in line with

the

original expectations.
As mentioned before, it can be easily done with the sound card.

that

time, I asked for feedback (screenshots of the same method) of

measured

filters to see if my 4,9 MHz filter is about in line with the 10

MHz

version. If some members do this measurement it is possible to

compare

results and find out if it is really a 'lottery'. As I

most

builders have their filter dimensioned in accordance with the

original

schematic and they all seems to work fine?
OK builders, please download the few kb program, connect your

to

the sound card, measure the shape of the filter and post the

screendump!

Thanks in advance,
Chris.

Without measuring to get
good filter is more lottery than predictable result. Only in
situation that somebody can use the same type of crystals

producer

and batch results might be comparable.

With the software and connecting the output of the AF amp to PC,

rgds
julius

Excellent page here not only provides the uncrippled Spectrogram for download but a noise generator and many other goodies as well.

73

Rahul VU3WJM

?

?

With the software and connecting the output of the AF amp to? PC, i wonder where do we set the BFO to find out the shape of our filter, assuming that we do not know the center frequency yet, or setting the BFO is not necessary?

rgds
julius

* REPLY SEPARATOR? *

On 7/20/2005 at 9:14 AM vdberghak wrote:

>Indeed measuring is knowing if the final result is in line with the
>original expectations.
>As mentioned before, it can be easily done with the sound card. At that
>time, I asked for feedback (screenshots of the same method) of measured
>filters to see if my 4,9 MHz filter is about in line with the 10 MHz
>version. If some members do this measurement it is possible to compare
>results and find out if it is really a 'lottery'. As I understand, most
>builders have their filter dimensioned in accordance with the original
>schematic and they all seems to work fine?
>OK builders, please download the few kb program, connect your BITX to
>the sound card, measure the shape of the filter and post the screendump!
>Thanks in advance,
>Chris.
>
>> Without measuring to get
>> good filter is more lottery than predictable result. Only in
>> situation that somebody can use the same type of crystals producer
>> and batch results might be comparable.
>
>
>
>
>
>
>
>Yahoo! Groups Links
>
>
>




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Indeed measuring is knowing if the final result is in line with

original expectations.
As mentioned before, it can be easily done with the sound card. At

time, I asked for feedback (screenshots of the same method) of

filters to see if my 4,9 MHz filter is about in line with the 10

version. If some members do this measurement it is possible to

results and find out if it is really a 'lottery'. As I understand,

builders have their filter dimensioned in accordance with the

schematic and they all seems to work fine?
OK builders, please download the few kb program, connect your BITX

the sound card, measure the shape of the filter and post the

Thanks in advance,
Chris.

Without measuring to get
good filter is more lottery than predictable result. Only in
situation that somebody can use the same type of crystals

and batch results might be comparable.

Chris

My BITX40 uses 24 volts on the IRF510 for a power output of 11

required the addition of separate sheilding, 2 ferrite beads on the

lead, and a paracitic suppressor (2 ohm 2 watt carbon resistor wound

turns of #16 AWG) between drain and output filter to tame it.

If you have a variable power supply, try bringing the voltage up

you have it working properly with 12 volts. I did not do this the

and it cooked an IRF510! 8-(

My IRF510 is mounted on the heat sink for a computer CPU. The

fan is mounted on the other side of the heat sink and turns on with

controlled voltage for the IRF510. I bolted the IRF510 directly to

sink, which is mounted to the chassis via 1/2 inch (1.3 cm) nylon

The fan housing is plastic so this isolates it from RF on the heat sink.

Next step might be to replace the IRF510 with push-pull IRF510s or

a 48 volt supply!

Arv K7HKL
_._


On Wednesday 20 July 2005 03:17 am, vdberghak wrote:

Hi all,
did anyone tried to put higher voltage on the IRF stage?
If so, I am interrested about the results like:
- stability,
- increase of output power.
If the output power is not much higher and other problems will

I will not try it...
Thanks,
Chris.




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Indeed measuring is knowing if the final result is in line with the
original expectations.
As mentioned before, it can be easily done with the sound card. At that
time, I asked for feedback (screenshots of the same method) of measured
filters to see if my 4,9 MHz filter is about in line with the 10 MHz
version. If some members do this measurement it is possible to compare
results and find out if it is really a 'lottery'. As I understand, most
builders have their filter dimensioned in accordance with the original
schematic and they all seems to work fine?
OK builders, please download the few kb program, connect your BITX to
the sound card, measure the shape of the filter and post the screendump!
Thanks in advance,
Chris.

Without measuring to get
good filter is more lottery than predictable result. Only in
situation that somebody can use the same type of crystals producer
and batch results might be comparable.

Yahoo! Groups Links