[AMRadio] Ranger Modulation


Larry Taft ltaft at charter.net
Thu Nov 16 12:06:03 EST 2006


Well, I tried...I wasn't right so now I'll be left

Sorry about the bad info.

73, Larry  K2LT

Gary Schafer wrote:
> You can't reverse the plate leads on the modulator tubes because it uses
> negative feedback from a winding on the transformer. Reversing the plate
> leads puts the feed back in phase rather than out of phase. It will
> oscillate!
>
> First check to see that you have proper grid current on the 6146. Low grid
> current will not allow full positive peak modulation because the tube runs
> out of steam with low drive. It is much more important to have proper grid
> current with AM than it is with cw. The tube has to have enough emission to
> handle the peak power 4x the carrier.
>
> Be sure the screen voltage is high enough on the 6146.
>
> Be sure that you are not overloaded - more power than the transmitter is
> rated for. If you have it loaded too heavy again the tube runs out of
> emission and will not allow the modulation peaks to go high enough.
>
> Try another 6146. 
>
> 73
> Gary  K4FMX
>
>   
>> -----Original Message-----
>> From: amradio-bounces at mailman.qth.net [mailto:amradio-
>> bounces at mailman.qth.net] On Behalf Of Jack Schmidling
>> Sent: Thursday, November 16, 2006 10:28 AM
>> To: Discussion of AM Radio in the Amateur Service
>> Subject: Re: [AMRadio] Ranger Modulation
>>
>> Larry Taft wrote:
>>     
>>> Try reversing the phase of the audio by swapping the output leads of the
>>> modulation xfmr.
>>>       
>> First I swapped the tubes to no avail.  I then swapped the wires and now
>> have a strange buzzing that I can not locate but it shows up on the
>> audio with the gain at zero.  Don't know if I barfed something up or not
>> but I vaguely remember reading somewhere that this an an indication to
>> reverse the leads.
>>
>>
>>     
>>> Weak tube in the audio chain causing lack of gain needed for the
>>> positive peak.
>>>       
>> Just ordered new audio tubes.
>>
>> Now I notice another discrepancy..... the manual that came with it says
>> to adjust the mod current to 75-90 ma.  The manual that Rick sent me for
>> the new version which I seem to have says 55-70 and no clue why the
>> difference.
>>
>> Which is correct and should I make an allowance for using 6L6's instead
>> of 1614's?
>>
>> js
>>
>> --
>> PHOTO OF THE WEEK: http://schmidling.com/pow.htm
>> Astronomy, Beer, Cheese, Fiber,Gems, Sausage,Silver http://schmidling.com
>>
>> ______________________________________________________________
>> AMRadio mailing list
>> List Home: http://mailman.qth.net/mailman/listinfo/amradio
>> Partner Website: http://www.amfone.net
>> Help: http://mailman.qth.net/mmfaq.html
>> Post: mailto:AMRadio at mailman.qth.net
>>     
>
>
> ______________________________________________________________
> AMRadio mailing list
> List Home: http://mailman.qth.net/mailman/listinfo/amradio
> Partner Website: http://www.amfone.net
> Help: http://mailman.qth.net/mmfaq.html
> Post: mailto:AMRadio at mailman.qth.net
>
>
>   




More information about the AMRadio mailing list

This page last updated 18 Oct 2017.