The AM Forum
November 07, 2024, 05:50:02 AM *
Welcome, Guest. Please login or register.

Login with username, password and session length
 
   Home   Help Calendar Links Staff List Gallery Login Register  
Pages: [1]   Go Down
  Print  
Author Topic: DX 60B...AM?  (Read 3288 times)
0 Members and 1 Guest are viewing this topic.
wa2tak
Member

Offline Offline

Posts: 110


« on: June 22, 2023, 08:57:01 AM »

I'm presently restoring a vy nice 60B.
Also have a nice HG-10 working with it.
Right now getting 40 watts on CW with 175 ma plate...xtal or VFO.
Alas, my AM is less than 10 watts with 50 ma plate...xtal or VFO.

Swapped out all tubes except the 6DE7...only have one.

1. what AM output should I shoot for?

2. any ideas on where to start?

Tnx,
Steve
Logged
WQ9E
Member

Offline Offline

Posts: 3289



« Reply #1 on: June 22, 2023, 09:18:19 AM »

Steve,

The DX-60 is controlled carrier so the resting carrier level is low and your results sound normal.  It will increase with modulation level so the best check of it is either a scope or on the air reports from someone who understands it is controlled carrier.

The DX-60 sounds nice but people used to full carrier AM will question why their S meter is moving up and down as their receiver AGC tracks the carrier level.

Controlled carrier rigs allow low cost AM operation that sounds good AND controlled carrier is highly compatible with amplifiers primarily intended for SSB operation because the reduced duty cycle of controlled carrier allows them to run at or very close to their SSB power rating which is definitely not the case when these low duty cycle designs (both power supply and cooling) are confronted with the duty cycle of high level AM modulation.

Many entry level rigs (i.e. the Knight T60) also used controlled carrier as did Drake with their 4 line gear.

Rodger WQ9E
Logged

Rodger WQ9E
wa2tak
Member

Offline Offline

Posts: 110


« Reply #2 on: June 22, 2023, 01:11:32 PM »

Thanks for the lesson...never stop learning in Ham Radio!

Yup...AM output does go up with audio.
Curiously, it topped out at 30 watts immediately AFTER my speech..then came down.

My next 'lesson' for today:
When I first fired it up...my AM output ( no speech ) was 20 watts.
Did my 'lesson 1' as above....say about 10 minutes...
during this time...the AM output went DOWN to that less than 10 watts that I had yesterday.

CW output no change at all.

Seems like I have a 'time' problem in AM.
Logged
wa2tak
Member

Offline Offline

Posts: 110


« Reply #3 on: June 22, 2023, 01:36:44 PM »

Things are getting more "interesting".
I had tested all the tubes before firing up the rig.

Today tested this 6DE7...looked 'funky'.
Previous one had a short.
Put one of the 6CL6 in...heard a low noise...vintage tube tester 100% now not working...

More 'lessons' in the works!
Logged
wa2tak
Member

Offline Offline

Posts: 110


« Reply #4 on: June 22, 2023, 03:59:59 PM »

Luckily it was only a fuse.
10 AMPS...should be 1 amp!!
Second time this has happened to me...the other was my PS23 power supply.
What the heck are these folks thinking???

6DE7 might be 'sorry'...got to get another.
Next...my "time" problem...as I don't have a thermal imager...( to find a bad resistor )..got to get some gas...CO2
Logged
Pete, WA2CWA
Moderator
Member

Offline Offline

Posts: 8140


CQ CQ CONTEST


WWW
« Reply #5 on: June 22, 2023, 05:59:01 PM »

Luckily it was only a fuse.
10 AMPS...should be 1 amp!!
Second time this has happened to me...the other was my PS23 power supply.
What the heck are these folks thinking???

6DE7 might be 'sorry'...got to get another.
Next...my "time" problem...as I don't have a thermal imager...( to find a bad resistor )..got to get some gas...CO2

Always good to check that all the correct parts and values are installed before applying power.
Harbor Freight has cheap  infrared thermometers to detect hot resistors or other parts:
https://www.harborfreight.com/search?q=infrared%20thermometer
Watch the cold spray. You don't want to shock a part into failure. I prefer the "medical" type of cold spray, It's not as severe and it's less expensive:
https://www.webstaurantstore.com/medi-first-23017-4-oz-cold-spray/57723017.html
Don't remember if drug stores carry something similar.
Logged

Pete, WA2CWA - "A Cluttered Desk is a Sign of Genius"
DMOD
AC0OB - A Place where Thermionic Emitters Rule!
Contributing
Member
*
Offline Offline

Posts: 1806


« Reply #6 on: June 22, 2023, 10:43:10 PM »

Here is a DX-60B in which enhancements can be made to increase modulation percentage and vary power output.



Phil - AC0OB

* AC0OB DX-60 Mnimal Upgrades.pdf (160.79 KB - downloaded 86 times.)
Logged

Charlie Eppes: Dad would be so happy if we married a doctor.
Don Eppes: Yeah, well, Dad would be happy if I married someone with a pulse.NUMB3RS   Smiley
wa2tak
Member

Offline Offline

Posts: 110


« Reply #7 on: June 23, 2023, 11:49:02 AM »

Welll.....it appears that the only "hot" thing is my MIKE CABLE.
In AM...my output is 12 watts...then...when I GRAB the mike cable...it goes to 20...speech puts it to around 30.
In PTT hold just the mike...its at 8 watts.

The mike is a Shure 404C high impedance.
Logged
wa2tak
Member

Offline Offline

Posts: 110


« Reply #8 on: June 23, 2023, 11:50:52 AM »

PS...have some ferrites over the cable.
Logged
WD5JKO
Member

Offline Offline

Posts: 2001


WD5JKO


« Reply #9 on: June 23, 2023, 12:36:44 PM »




"when I GRAB the mike cable...it goes to 20"


Try running a wire from the microphone to the front panel of the rig. If there is a lot of RF in the shack, this will shunt away the RF flowing on the coaxial cable shield.

Jim
Wd5JKO
Logged
wa2tak
Member

Offline Offline

Posts: 110


« Reply #10 on: June 23, 2023, 01:11:01 PM »

Have a LOT of RF 'output'...the chassis..6164 box 100% 'in the air'...as I"ve been 'working' on it.
Will button it up.
But heck...watts out is watts out..hihi...

Like antennas...folks 'complain' about common mode current radiating from the coax line...
"watts out is watts out...
Logged
wa2tak
Member

Offline Offline

Posts: 110


« Reply #11 on: June 23, 2023, 03:07:32 PM »

Hello Jim:

"Good eye" you have.
Buttoned it up.
All fine.
Just about done with it....except my ignorance on L1.

Rig-work...looks like new...even polished the screws.

Permit me to call your attention to my "DX100 ala GTO"...my spot on QRZ...only took me 1-1/2 years...

Tnx,
Steve
Logged
DMOD
AC0OB - A Place where Thermionic Emitters Rule!
Contributing
Member
*
Offline Offline

Posts: 1806


« Reply #12 on: June 23, 2023, 03:11:29 PM »

Welll.....it appears that the only "hot" thing is my MIKE CABLE.
In AM...my output is 12 watts...then...when I GRAB the mike cable...it goes to 20...speech puts it to around 30.
In PTT hold just the mike...its at 8 watts.

The mike is a Shure 404C high impedance.


Some more suggestions

1) Check your mic shield grounds, with an ohmmeter, to see if you have continuity from the shield to the chassis ground and to the 1/4" mic plug.

2) change R17 to a 10k 1/2W.

3) change C29 to a 150pF Silver Mica

4) place a .005uF 500V ceramic disk cap at the junction of  R21 and R22 to ground.



Phil
Logged

Charlie Eppes: Dad would be so happy if we married a doctor.
Don Eppes: Yeah, well, Dad would be happy if I married someone with a pulse.NUMB3RS   Smiley
Pages: [1]   Go Up
  Print  
 
Jump to:  

AMfone - Dedicated to Amplitude Modulation on the Amateur Radio Bands
 AMfone © 2001-2015
Powered by SMF 1.1.21 | SMF © 2015, Simple Machines
Page created in 0.115 seconds with 18 queries.