Home |
Search |
Today's Posts |
|
#1
![]() |
|||
|
|||
![]()
On Sun, 23 Mar 2008 12:39:35 -0700 (PDT), Artem
wrote: On Mar 22, 8:48 pm, K7ITM wrote: 15 floor of 16-floor building. But I think that in this case "ground" are building walls. There is a hint he it is common that tall buildings incorporate a lot of steel, and that will likely act as a shield. I hope this antenna is not mounted inside! It's not mounted at all. But for tests I'm put this antenna outside. vertical) -- -- where "close" means relative to a wavelength. So the small balanced loop is especially good for LF and VLF work. my reason was make narrow-band antenna. For reject all out of band noise. A reasonable thing to do, though a good receiver with a low-distortion and fairly narrow-band front end should not have trouble with out-of- band signals (noise). Do you have a quantitative measure of just how strong this out of band noise is? Not. Just not received. I'd personally much rather use a preselection filter separate from the antenna, and close to my operating position, to reject out-of-band signals. Even though the antenna you have described has very high Q, I believe I could do better with a two or three resonator filter running at lower Q, since the slope of the attenuation versus frequency is much greater. I will receive QRSS at all. And I think that it would be best way is using narrow-band antenna - filter - synchronous detector. there was some especially strong signal in the band, I would at least consider a fixed-tuned bandpass filter that covered my band of interest, assuming that band is fairly narrow such as 7.0-7.1MHz. Can you tell that you are getting the expected antenna bandwidth, about 3kHz at the 3dB points at 7MHz? I'm just testing. I will purchase RF generator in next week and test. Now I have only self-oscillation frequency. Antenna looks like working. I'm receiving a lots of Morse signals at 7.000 - 7050 Mhz. But I cant recognize any voice signal. This is receiving signal. Looks like narrow-band enough. This is not self oscillation. In self oscillation voltage a few volts. http://img148.imageshack.us/my.php?image=ds0000bu6.png This is schematics. I'm not sure that I'm correct use gual gate transistors. http://img210.imageshack.us/my.php?image=schbr1.jpg I'm not sure that using shielded cable and ferrite chocks is good idea. http://img171.imageshack.us/my.php?image=hwak2.jpg np0 caps. http://img370.imageshack.us/my.php?image=capsnf8.jpg Please see the US ARRL frequency chart he http://www.arrl.org/FandES/field/reg...ands_color.pdf 7000 to 7050 MHz is RTTY and Morse code only. If you want voice, probably SSB try 7125 to 7300 MHz. |
#2
![]() |
|||
|
|||
![]()
On Mar 25, 7:29 am, JosephKK wrote:
Please see the US ARRL frequency chart he http://www.arrl.org/FandES/field/reg...ands_color.pdf 7000 to 7050 MHz is RTTY and Morse code only. If you want voice, probably SSB try 7125 to 7300 MHz. I'm in Europe. We have only 7000....7100. |
Reply |
Thread Tools | Search this Thread |
Display Modes | |
|
|
![]() |
||||
Thread | Forum | |||
About a narrow filter at 10.7 MHz | Homebrew | |||
Narrow Band FM bandwidth and channel spacing | Equipment | |||
Flower Pot Antenna a Dual-Band (20m and 10m) 'portable' Antenna | Shortwave | |||
Narrow & Wide............ | Shortwave | |||
Antenna Specialists MON-4 VHF Low Band Scanner antenna - Can I trim it for 6 meter use ? | Antenna |