12 Threads found on edaboard.com: Hf Oscillator
Hi I am building an HF oscillator circuit which requires a bf247c but this is not cheaply available.
Are there any equivalents?
RF, Microwave, Antennas and Optics :: 02-17-2015 05:50 :: neazoi :: Replies: 4 :: Views: 168
I am thinking of the attached Quadrature oscillator covering 1KHz-30MHz, and I wonder if this would work and if it will be stable enough to be used on HF ham bands? (as it is, no decreasing of the range)
I do not expect crystal stability, but I have read that the thermal stability of these chips is 40ppm per C!
Also the max freq of the
RF, Microwave, Antennas and Optics :: 11-17-2014 07:55 :: neazoi :: Replies: 4 :: Views: 266
If this is a normal crystal then this will specify a capacitive load for typical operation.
The problem will be that circuit layout is unknown and produces a significant capacitance.
The two capacitors for HF work are often around 10pF, hence the layout issue.
Keep the crystal leads close to the component pins, track the capacitors close to the
Embedded Systems and Real-Time OS :: 09-11-2013 16:00 :: pinout :: Replies: 1 :: Views: 520
I came across this HF band kit that says hooking up will enable you to receive HF bands ...30m, etc
basically i want to receive 10 MHz signal (which is not in 30m band) but this kit is programmable with software (so its a Software defined radio), t
RF, Microwave, Antennas and Optics :: 09-05-2013 03:57 :: Ow@i$ :: Replies: 2 :: Views: 309
I made a HF pedal for my welder with an illuminated footswitch. I wired it up by trial and error, and it sort of works, but I don't know why!
The foot switch makes a circuit for a secondary output primary coil which energizes a spark gap oscillator that generates high frequency bursts of high voltage to help start the arc. The LED lights up whe
Show your DIY :: 05-21-2013 10:12 :: t0m :: Replies: 0 :: Views: 679
Hello I am trying to make a simple RTTY oscillator for the HF bands that can accept 1.2KHz and 2.2KHz audio tones.
Can this be done using a quartz crystal for better stability, or the crystal does not allow so much deviation?
Also are there any sources of such a schematic?
RF, Microwave, Antennas and Optics :: 06-29-2012 06:00 :: neazoi :: Replies: 0 :: Views: 238
Hello I alter the frequency of an HF (1-30MHz) crystal oscillator using an MV209 varicap.
I need to replace it with a greater capacitance range varicap to increase the tuning range, as much as the crystal permits it. Which one should I use?
1) 9.5v maximum tuning voltage
2) junction operating temperature more than 80C, since it
Analog Circuit Design :: 02-14-2012 19:17 :: neazoi :: Replies: 0 :: Views: 452
Hi every one,
I do not know if I am in right topic section. I need some schematic circuit diagram of an HF Plastic welding machine (for creating Photo Albums). I want to assemble one for me by using FU 501 triode as the main oscillator/output tube.
Service Manuals, Requests, Repair Tips :: 01-24-2012 13:34 :: Saba Khan :: Replies: 0 :: Views: 1093
I have built a hf start module for a tig welder, its basically a high voltage radio frequency spark gap oscillator driven by a car ignition coil, its aim is to start the arc from the electrode to the work esp on low welding voltages.
It works well on my dc output alternator generator welder, however I tried this device on a ac stick w
Hobby Circuits and Small Projects Problems :: 03-15-2010 03:44 :: dr pepper :: Replies: 1 :: Views: 4886
You will be best off by using inductive coupling. Especially if everything is in a large metal box.
In the EU there are rules on unintentional radiation in the HF ISM bands. You can exceed these with just tens of watts of power.
RF, Microwave, Antennas and Optics :: 05-19-2008 18:06 :: flatulent :: Replies: 11 :: Views: 1846
I need some help..Ive been trying to build a RF amplifier for 12MHZ .But ive had some problems driving power.
The basic oscillator is a colpitts one with crystal using a BJT 2N2222 .Output is taken from BJT colector.The bjt colector also has a choke tied to +Vcc.But I need to boost output power. Just 1 BJT isnt enough for getting 180Vpp and 20
RF, Microwave, Antennas and Optics :: 08-12-2007 16:01 :: meridio :: Replies: 2 :: Views: 1223
The problem is tricky - he wants to have consumption about 3 microwatts .
So oscillator must be very efficient , that put restriction on using UHF, which is preferred for such communication - antenna lenght could be very small)
I think you can experiment with ferrite antennas on LF-HF band to keep power consumption low.
Or may be usltras
Hobby Circuits and Small Projects Problems :: 01-20-2006 11:09 :: artem :: Replies: 2 :: Views: 882