Copper Talk » Ask The Tech » Modifications » 2959/2970 swing mod « Previous Next »

Author Message
Top of pagePrevious messageNext messageBottom of page Link to this message

Jr45698
Posted on Monday, April 15, 2002 - 8:54 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

i've seen a mod around for these radios to make them swing from a low dead key consisting of adding a 1N4001 diode in line with R264. Has anyone tried this ? Is it a good or not so good mod to do?
Top of pagePrevious messageNext messageBottom of page Link to this message

Inspector
Posted on Tuesday, April 23, 2002 - 8:03 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

It actualy should be a 1N4001 inline with a 100ohm resistor added paralel to R285 or C300 (with the banded end of the diode toward the rear of the radio). This set-up gives the best negative peak compression without clipping (neg. peaks at about 95% compression while pos. peaks modulating WAY above 100%...depending on your mic-gain setting and your low dead-key at about 1.5 to 2.0 Watt. An amp will LOVE this set-up and all semiconductors will run cooler:-)
Top of pagePrevious messageNext messageBottom of page Link to this message

Jyd
Posted on Saturday, April 27, 2002 - 8:59 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

what are we talking about here a swing mod or npc mod
Top of pagePrevious messageNext messageBottom of page Link to this message

Inspector
Posted on Friday, May 03, 2002 - 8:29 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

The NPC-RC mod IS the best swing mod, so as not to create exessive RFI. If you just rip-out the AMC limmiter and throw-in any old switching diode, you will have tremendous swing...and you will have created an RFI monster. With the NPC mod (tuned with an O-scope), you should be able to dead-key 2 Watt and swing to almost full power without distortion i.e. clipping of the negative peaks of the waveform...the major cause of RFI. This is "swing"...No?

Add Your Message Here
Post:
Username: Posting Information:
This is a private posting area. Only registered users and moderators may post messages here.
Password:
Options: Enable HTML code in message
Automatically activate URLs in message
Action: