Go Back   WorldwideDX Amateur Radio Forums > Citizens Band Related > CB Band and CB Radios


Amateur Callsign Lookup
Enter Callsign:

NPC for AM Transformer radios is HERE... Tubed, Solid State, etc. ANY high level TX

Like Tree1Likes

Reply
 
LinkBack Thread Tools Display Modes
  #65  
Old 01-10-2011, 03:23 PM
Senior Member
iTrader: (0)
 
Join Date: Dec 2010
Posts: 320
Kamikaze is on a distinguished road
Default


Quote:
Originally Posted by VA3ES View Post
Interesting observation. I completely overlooked that aspect. Now why would the neg. cycle load resistor affect NFB, when that resistor is not in circuit except during neg. cycle cut-off?
The final's load and the negative cycle load are in parallel. The negative cycle loading is there throughout the neg cycle. The postive cycle only sees the final's load.

Quote:

Positive opeak stretching can only go so far before you start to overload simple diode detectors. I believe that a simple diode detector will start to distort at about ~130-140% positive. (Thus the broadcast standard of maximum 125% positive.)
Common diode detectors start distorting above 30%. They really fall apart above 125%. Some distortion is tolerated as a tradeoff for improved SNR.

Quote:

Timtron (Tim, WA1HLR) has promoted the concept of "Turbo-modulation", where the standard mod transformers in Heath and Johnson rigs are rewired as an autotransfomer. He claims 120% positive peaks with this mod. Having several DX-100's and Apaches, I haven't tried it.
Timtron knows what he's doing. The "turbo" connection for mod transformers along with inverse feedback to make the modulators act more like triodes as far as load impedance really wakes those rigs up.

Reply With Quote
  #66  
Old 02-13-2013, 06:43 AM
Member
iTrader: (0)
 
Join Date: Oct 2011
Posts: 35
479tx is on a distinguished road
Default

Quote:
Originally Posted by Toll_Free View Post
If you REALLY want to increase the complete talk-power on those units (I've been working with the 858 Unidens and the processors / clippers in them for about 25 years), add a diode or two to the POSITIVE side. This will still allow for some amount of clipping (good), but will INCREASE the positive side.

OR, keep a SILICON rectifier diode on the positive side, and a germanium or shottkey on the negative side. I did just this in a Lou Franklin clipper, and it make it about twice as loud: Not bad when you consider the processor gets the same compliments by itself!

--Toll_Free
I have a TRC-457. I'm interested in the two mods above to the diode pair/clipper that comes stock. What net effect would adding a diode or two in series with d21 (positive side on my radio) or replacing the stock diode @ d22 (negative side) with a schottky have? I assume you'd create favorable conditions for higher positive peaks while still keeping the negative peaks in check? (Asymmetric modulation instead of ~100%)

Anyone try this on an 858 radio's clipper? I have a schottky diode sitting right here...

Reply With Quote
  #67  
Old 02-14-2013, 05:51 PM
Junior Member
iTrader: (0)
 
Join Date: Dec 2012
Posts: 9
scorpion is on a distinguished road
Default

What is this supposed to do in the radio
if you don't mind me asking and would this
work in a Texas Ranger 936ffc.

Reply With Quote
  #68  
Old 02-19-2013, 09:02 PM
longhaireddwb's Avatar
Senior Member
iTrader: (7)
 
Join Date: Oct 2008
Location: Colorado Springs, CO
Posts: 422
longhaireddwb is on a distinguished road
Default

I finally remembered about this mod and built the circuit on a perf board. Hooked it up in a Cobra 25 on the D10 diode (anti-spike), ran the ground and B+ and it did nothing more to my audio as herd from others around town. Not louder, not more.
Its possible I did something wrong but this is so simple I know I didn't do it wrong.

Whats up with this?
__________________
Yaesu FT950, Yaesu 2900, Galaxy 48T, Galaxy 94HP, 98VHP, Plus a dozen or so little radios!

Reply With Quote
  #69  
Old 09-17-2013, 11:27 AM
Junior Member
iTrader: (0)
 
Join Date: Oct 2011
Posts: 5
domino is on a distinguished road
Default

I put it in my 29 yesterday in combo with the J36 mod. I ended up with a about 33 ohm resistor. 3, 100ohm, 1W. Half watt resistors got hot! I now wanna try the LM317 supply

Reply With Quote
  #70  
Old 09-17-2013, 11:28 AM
Junior Member
iTrader: (0)
 
Join Date: Oct 2011
Posts: 5
domino is on a distinguished road
Default

You really need a scope to set up. You gotta be able to see the negative peaks
9C1Driver likes this.

Reply With Quote
Reply

Bookmarks

Tags
npc mod
Worldwide Radio Forum



Thread Tools
Display Modes

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 On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
WARNING, Don't Carry a Scanner into Michigan!!! Charger383 Scanning & Shortwave Listening 34 05-05-2011 11:24 AM
FEMA National Update: Monday, December 21, 2009 FEMA FEMA Declarations and National Updates 0 12-22-2009 06:10 PM
FEMA National Update: Tuesday, April 14, 2009 FEMA FEMA Declarations and National Updates 0 04-14-2009 07:10 AM
FEMA National Update: Sunday, April 12, 2009 FEMA FEMA Declarations and National Updates 0 04-13-2009 05:40 PM


All times are GMT -7. The time now is 07:13 PM.


Powered by vBulletin®
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Search Engine Optimization by vBSEO 3.6.0
Worldwide Radio Forum