Question about shifting tuning range


Tim Tyler II
 

I have a question: My 40 meter 5Watter tunes from 6.990 to 7.045. Should I try removing a turn or two from L7 and see if that moves the tuning range up in frequency, or am I way off base?

Also, I’m wondering if anyone has any recommendations for adding a speaker. I’ve been using some Apple iPhone earbuds and the audio frequency range is such that signals outside the passband can be heard well enough to be distracting...and I notice after periods of operating that I may have stressed my ears (obviously need to turn down the af gain but I’m not realizing that while it matters.) I’m wondering if I’d be better off with a speaker.

I’ve been having a ball on 40 meters with my 5watter. I am so glad I decided to go this route, and deliberately paint myself into a CW corner so I would be forced to finally learn this wonderful mode. This is currently my only radio, with a 5W17x waiting in the wings to be built.

Thanks, 
Tim  NC0Q


 


On 5/23/21 10:17 PM, Tim Tyler II wrote:
I have a question: My 40 meter 5Watter tunes from 6.990 to 7.045. Should I try removing a turn or two from L7 and see if that moves the tuning range up in frequency, or am I way off base?
You should lower the value of Cx in the VCXO circuit by 5 percent +/-...I know...hard to do...keep the turns as they are on L7

Also, I’m wondering if anyone has any recommendations for adding a speaker. I’ve been using some Apple iPhone earbuds and the audio frequency range is such that signals outside the passband can be heard well enough to be distracting...and I notice after periods of operating that I may have stressed my ears (obviously need to turn down the af gain but I’m not realizing that while it matters.) I’m wondering if I’d be better off with a speaker.

Tim, I myself have a hard time listening to CW using earphones...just don't like unbuffered sound.

My favorite speaker is the old Radio Shack Realistic communications speaker, Cat # 21-549.

It is very efficient, producing lots of audio...I got all 4 of mine on ebay

-Diz


I’ve been having a ball on 40 meters with my 5watter. I am so glad I decided to go this route, and deliberately paint myself into a CW corner so I would be forced to finally learn this wonderful mode. This is currently my only radio, with a 5W17x waiting in the wings to be built.

Thanks, 
Tim  NC0Q


Tim Tyler II
 

Okay, great. I found a decent-looking RS #21-549 on eBay and ordered it. Thanks for the suggestion.

I’m glad I asked about shifting the tuning range. I guess it’s time for me to buy a capacitor assortment from somewhere.

Thanks again,

-Tim NC0Q


 


On 5/24/21 11:35 PM, Tim Tyler II wrote:
Okay, great. I found a decent-looking RS #21-549 on eBay and ordered it. Thanks for the suggestion.

I’m glad I asked about shifting the tuning range. I guess it’s time for me to buy a capacitor assortment from somewhere.

You can always twist 2 pieces of MAGNET WIRE together about 3 inches long...

install at Cx and trim length until you reach a low end of 7000.001 KHz :)

-Diz


Thanks again,

-Tim NC0Q


Tim Tyler II
 

How clever. I was thinking of swapping in low-value caps in series with Cx until I got the results I wanted, but your idea sounds like a lot more fun. Thanks!!

Tim


Tim Tyler II
 

Ha! Diz, you’ve introduced me to the “gimmick capacitor.” Never heard of this.

-Tim NC0Q 


 

yea :) ... probable easiest to just solder two parallel wires into the Cx holes and then take some needle nose pliers and twist.

Then adjust by cutting 1/8th inch at a time until desired value is achieved.

On 5/25/21 1:19 PM, Tim Tyler II wrote:
Ha! Diz, you’ve introduced me to the “gimmick capacitor.” Never heard of this.

-Tim NC0Q 


Tim Tyler II
 

I haven’t gotten around to trying the gimmick capacitor yet....But I have another question. If I’m not using J7 (no “RF gain” pot installed,) are Q6 & Q8 even doing anything? Is the AGC active with J7 unpopulated?

Thanks!
-Tim NC0Q 


Tim Tyler II
 

Or is audio from output of U4 rectified by D9 and used to turn on Q6 and Q8, siphoning inputs for U2 and U3 to ground?

-Tim, “mere assembler”


 

J7 only provides an IF gain over-ride.

Q6 & Q8 are always an active part of the AGC circuit...look at the "AGC" line

-Diz

On 6/2/21 8:21 PM, Tim Tyler II wrote:
I haven’t gotten around to trying the gimmick capacitor yet....But I have another question. If I’m not using J7 (no “RF gain” pot installed,) are Q6 & Q8 even doing anything? Is the AGC active with J7 unpopulated?

Thanks!
-Tim NC0Q 


 

Yup!

On 6/2/21 9:03 PM, Tim Tyler II wrote:
Or is audio from output of U4 rectified by D9 and used to turn on Q6 and Q8, siphoning inputs for U2 and U3 to ground?

-Tim, “mere assembler”


Tim Tyler II
 

Hey Diz, I tried that RS #21-549 speaker last night. Works FB!! Thanks for the suggestion.

-Tim NC0Q