Esoteric question on tuner inputs and RF design - Page 4 - diyAudio
Go Back   Home > Forums > General Interest > Everything Else

Everything Else Anything related to audio / video / electronics etc) BUT remember- we have many new forums where your thread may now fit! .... Parts, Equipment & Tools, Construction Tips, Software Tools......

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 16th April 2012, 04:24 PM   #31
Mike B is offline Mike B  United Kingdom
diyAudio Member
 
Join Date: Jun 2011
Location: Oxfurdshy'r
My CGIRS (Compulsive Get It Right Syndrome) has forced a change of plan
This afternoon I made the same <1/4 wave length (690mm - 27.18inch) as a 2 turn (109.9mm - 4.33inch)
I rechecked the SRF & found an error in my previous 2 turn number.
The new 2 turn is 111MHz - about right for 88-108 - so I think I'm done.
  Reply With Quote
Old 16th April 2012, 08:32 PM   #32
Lavcat is offline Lavcat  United States
diyAudio Member
 
Lavcat's Avatar
 
Join Date: Dec 2009
Location: New Jersey USA
Quote:
Originally Posted by Lavcat View Post
Some years ago (quite a few) I made a Y antenna for the FM band and matching transformer.
Duh, I mean "V".
  Reply With Quote
Old 17th April 2012, 01:52 AM   #33
diyAudio Member
 
Join Date: Mar 2007
Location: Canandaigua, NY USA
Well, tonight I installed the new antenna in the shop. It pulls in signals just fine, but I quickly realized what the real problem is. There's a bank of florescent lights in the shop that just tear up the reception. I don't know if it's a bad ballast or if that's just par for the course. I'll bring in a portable radio and see if I can localize the problem to just a couple lights, or if it's all of them. It's going to be hard to move the antenna further away and I don't know if it's possible to filter this stuff. Hints and kinks?
__________________
I may be barking up the wrong tree, but at least I'm barking!
  Reply With Quote
Old 17th April 2012, 02:23 AM   #34
diyAudio Member
 
Joe Roberts's Avatar
 
Join Date: Feb 2006
Location: VA
Electronic ballasts are notorious and not easy to deal with, especially in a commercial setting that you don't own/control.

Some ballast designs are better than others. Potentially really nasty variable duty cycle PWM circuits are at the heart of these things so a unshielded and unfiltered one can be really bad for EMI.

MAYBE it is a defective ballast...got a portable radio with Aircraft band on it (VHF AM)?

Might be time for INTERNET RADIO....don't knock it till you tried it. No, it doesn't sound great but better than nothing. I listen to live streams of my favorite Austin, New Orleans, and Philly stations all the time. Not much DIY opportunity in it but there is music to be had.
  Reply With Quote
Old 17th April 2012, 02:46 AM   #35
diyAudio Member
 
Join Date: Apr 2003
Location: Portland,Oregon
Blog Entries: 4
Send a message via AIM to DigitalJunkie
I've had great results using a J-pole,both RX and TX.
They can be a bit fiddly to get tuned right,but once they are,they rock.
  Reply With Quote
Old 17th April 2012, 04:36 AM   #36
diyAudio Member
 
Join Date: Mar 2007
Location: Canandaigua, NY USA
I don't listen to SW much anymore, but my Sony 2010 makes a great noise sniffer. BTW, I measured my "aircraft cable" and it has a capacitance of 67.7 pF/foot, and a velocity factor of (I think) 0.66, not that I think it has much RF application. It's Teflon and the dissipation factor is 0.00015 so it should sound decent.
__________________
I may be barking up the wrong tree, but at least I'm barking!
  Reply With Quote
Old 17th April 2012, 10:56 AM   #37
DF96 is offline DF96  England
diyAudio Member
 
Join Date: May 2007
VHF interference from fluorescent tubes is likely to come from the gas discharge itself, not the ballast. In essence, you have a very hot antenna radiating Johnson noise. Ballast noise mainly affects lower frequencies. Your incoming signal has been attenuated by the building structure. Try positioning your antenna near a large window on the side of the building which faces the transmitter.

At one time, UHF/microwave noise sources for receiver testing were made by installing a discharge lamp across a piece of waveguide.
  Reply With Quote
Old 17th April 2012, 04:01 PM   #38
diyAudio Member
 
Join Date: Mar 2007
Location: Canandaigua, NY USA
Quote:
Originally Posted by DF96 View Post
Try positioning your antenna near a large window on the side of the building which faces the transmitter.

At one time, UHF/microwave noise sources for receiver testing were made by installing a discharge lamp across a piece of waveguide.
You vastly overestimate my options in this situation!

That's interesting about fast noise sources. Yet another way to generate random numbers?
__________________
I may be barking up the wrong tree, but at least I'm barking!
  Reply With Quote
Old 18th April 2012, 10:49 PM   #39
diyAudio Member
 
Speedskater's Avatar
 
Join Date: Sep 2002
Location: Lakewood, Ohio
I had three different brands of florescent lights in my garage. One of the brands made lots of RFI in the FM band, it's not in the garage any more. It was a more expensive brand from the orange big-box store, it's not in the garage anymore.
__________________
Kevin
  Reply With Quote
Old 19th April 2012, 02:54 AM   #40
diyAudio Member
 
Join Date: Mar 2007
Location: Canandaigua, NY USA
Just to close this out, I did some sniffing with the 2010 and was amazed at how bad things were in the shop. There's no area to place the antenna that offers any real advantage over where it is right now. Still, it works pretty well, and better than the twin lead dipole it replaces. Maybe someday we'll be able to run a lead outside, but for now this is it. The Pandora is a good idea, but a few people are already doing it and my guess is too many would slow down the network to the point where management would say no to everyone.
__________________
I may be barking up the wrong tree, but at least I'm barking!
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Esoteric p2 / Clock (question) XXX Digital Source 2 27th December 2010 06:24 AM
Larsholt fm tuner front end for JLH tuner design-Any still available? djsb Analogue Source 0 25th December 2008 04:46 PM
Hey, where did my aux/cd/tuner inputs go? Audiofirst Analogue Source 5 21st July 2007 10:27 AM
An esoteric noise question scott wurcer Analogue Source 3 4th March 2004 04:52 PM
Question about esoteric resistors: Tantalum, Riken Ohm, Holco, etc. Eric Solid State 1 22nd August 2001 06:52 PM


New To Site? Need Help?

All times are GMT. The time now is 05:29 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2