Warning: Creating default object from empty value in /homepages/11/d132647312/htdocs/Amfone/mkportal/include/SMF/smf_out.php on line 47
ART-13 operational!




 
The AM Forum
March 28, 2020, 05:19:20 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: ART-13 operational!  (Read 1819 times)
0 Members and 1 Guest are viewing this topic.
KD2AZI
Member

Offline Offline

Posts: 18


« on: December 20, 2019, 01:54:40 PM »

So after six months of work my ART-13 is finally hooked up and putting out some power.  I tried to get into the AM Carrier net last Sunday and had some glitches.

I'm new to AM so have some questions, and appreciate any suggestions!
My BC-312 receiver's muting relay was not working so I replaced with a P&B unit, grounding the antenna and first audio grid when the transmitter is keyed.  However, I'm still getting a horrible squeal/feedback when transmitting.  I tried removing the receiver antenna line from the ART-13 relay to no improvement.  In fact completely disconnecting the receiver's antenna has the same results.  Even grounded I still get the feedback.  The only thing I didn't try is moving the receiver a few feet from the transmitter.  Any ideas?

I'm putting out 80 watts, and is that enough for "regional" 40m contacts? - the net had trouble making out my transmission.  I don't have a high-gain antenna, and wondering if all you gents use big amps?  (I have a Viking T-bolt and an HK Warrior perhaps I could try)

My plate/screen voltages are 1100/425 w/no sag
Modulation looks good on the scope w/carbon mic
Radio's PTO has little drift, and using digital frequency counter.
Antenna is tuned to around 3885 (Gap Titan DX) - no other choice in antennas.
Logged
W6TOM
Contributing
Member
*
Offline Offline

Posts: 437


« Reply #1 on: December 20, 2019, 03:45:23 PM »

   For AM you really need the most power you can get and best antenna. My ART-13 which I run off the dynamotor gives me around a 130 watts of carrier on 75 meters, I use a D-104 microphone. The carbon mic did not modulate well or get good audio reports.

   These sets were made to load into a trailing wire antenna and not a 50 ohm load, I think 80 watts of carrier is a bit on the low side.

    Henry, WA7YBS, has a lot of good info on his site about the ART-13 including using an off board capacitor to improve loading.

    https://www.radioblvd.com/art13.htm

Logged
N8ETQ
Member

Offline Offline

Posts: 786


Mort


« Reply #2 on: December 20, 2019, 05:49:05 PM »

  

  yo'

          U may want to try padding in a 500 pf cap.  Hook it to the
"LOADING" connection on the side panel and chassis.  One of those
"Big Un's" with screw connections.   The power will come up.
Disconnect the cap when on 40 or higher.

GL

/Dan
N8ETQ  CLE



Logged
KD2AZI
Member

Offline Offline

Posts: 18


« Reply #3 on: December 20, 2019, 09:39:08 PM »

Thanks guys - I have been all over that Radio Boulevard site, and I do have a 1000 pf variable hooked up to the COND Terminal. at 3885, the best loading is with minimum capacitance.  I have a bunch of spare 813s, I'll try a few others and see if output improves.

Also, I think I may be over-modulating; the pattern has some flat lines in between.  I did that mod in the audio unit to change R203 from 15 to 4.7k for the carbon mic.  I'll take another look at this.
Logged
SM6OID
Member

Offline Offline

Posts: 185



« Reply #4 on: December 22, 2019, 05:16:57 AM »

Hi!

Another ART-13 on the air, that is good news!
I have two ART-13 in service, one with LF oscillator.
With increased bias the T-17 carbon microphone works fine, but an ElectroVoice 638 with W2IHY EQ makes great audio.
Currently I see a hair shy of 130 W (3.7 MHz) on a good day with dynamotor, supply voltage is a bit low, 26.8 V at load.

Logged

RADIO: 51J-4, R-390A, SP-600 JX-21, BRT-400, Set No 19, T-47/ART-13, RF-590, SRT CR91, BC-312D, BC-348Q, HF-8020/8030/8010A/8090,  and much more...

ENGINE: Zvezda M50 F6L (V12), Rolls-Royce Meteor mk4B/2 (V12), Rolls-Royce B80 (inline 8 ) and much more
KD2AZI
Member

Offline Offline

Posts: 18


« Reply #5 on: December 22, 2019, 12:02:29 PM »

Yes, it is good news.  Having fun with it.  I did the mod to replace the a resistor in the audio section to a lower value for the carbon mic bias - I'm over modulating now, and need to revisit that.

I have a bunch of 813s I've been hoarding and I'll try boosting the B+ a bit and trying some different tubes to see if I can increase the wattage a bit. 
The antenna is tuned to 1.31 SWR @ 3885 and I think that's the best I'll be able to do with my small space. 
Will try again next week after working out some glitches.

By the way, even with receiver muting it's overloading on Xmit which is actually making it easy to spot!
73




* IMG_2481.jpeg (2550.11 KB, 4032x3024 - viewed 83 times.)
Logged
SM6OID
Member

Offline Offline

Posts: 185



« Reply #6 on: December 23, 2019, 10:40:40 AM »

Hi!

You know what, before you do anything about the mic bias resistor, have a look at the power output "issue".
First, play around with alternative setting of E-C-D knobs, it is possible that you will find a settings combination that will give you more power! If this is a dead end, swap PA tube and see what happens?
How much indicated GRID DRIVE do you see?

Logged

RADIO: 51J-4, R-390A, SP-600 JX-21, BRT-400, Set No 19, T-47/ART-13, RF-590, SRT CR91, BC-312D, BC-348Q, HF-8020/8030/8010A/8090,  and much more...

ENGINE: Zvezda M50 F6L (V12), Rolls-Royce Meteor mk4B/2 (V12), Rolls-Royce B80 (inline 8 ) and much more
W6TOM
Contributing
Member
*
Offline Offline

Posts: 437


« Reply #7 on: December 23, 2019, 04:41:41 PM »

  I have two of these transmitters, one is an early ATC and the other an ART-13, I had a problem at different timers with both in that the modulation would go away. I decided to try replacing all the electrolytic capacitors in the speech amp, that solved this issue.


* New Cap & Terminal Strip.JPG (211.66 KB, 1024x742 - viewed 93 times.)

* Old New Caps.JPG (165.04 KB, 1024x598 - viewed 88 times.)
Logged
KD2AZI
Member

Offline Offline

Posts: 18


« Reply #8 on: December 26, 2019, 02:39:23 PM »

Yeah, I replaced those capacitors too...on another site the pros identified those as paper in PCB oil...and those electrolytics in the audio module took some time to replace.

I'm now getting about 120 watts out on 80 meters, and working out the glitches slowly - with some mods to the receiver muting the feedback is gone.
I'll hopefully be ready for another QSO attempt in early Jan!
Logged
SM6OID
Member

Offline Offline

Posts: 185



« Reply #9 on: December 27, 2019, 03:17:01 AM »

Hi!

Nice of you to share the good news!

What was the reason for the "low power condition"?
Poor tuning strategy or a tired 813? Or what?

Please let share your experience, so we all can learn!
Logged

RADIO: 51J-4, R-390A, SP-600 JX-21, BRT-400, Set No 19, T-47/ART-13, RF-590, SRT CR91, BC-312D, BC-348Q, HF-8020/8030/8010A/8090,  and much more...

ENGINE: Zvezda M50 F6L (V12), Rolls-Royce Meteor mk4B/2 (V12), Rolls-Royce B80 (inline 8 ) and much more
KD2AZI
Member

Offline Offline

Posts: 18


« Reply #10 on: December 27, 2019, 09:25:03 AM »

The low power condition was addressed by increasing B+ to 1150v, and trying different 813s. I've been hoarding them from hamfests.  (odd that I never noticed that 813s have a couple different plate makeups, btw).  Grid drive is just left of center.  I have not experimented with adjusting the screen supply - it's about 420v

Tuning was easy to figure out, and the frequency counter helps keep me from tuning in a harmonic - which I discovered when trying to tune up on 40m.

Tune-up is a bit tricky when control E is close to "200;" you've got to be careful not to switch between scales while tuning up - the manual warns about this - and it's happened once...or twice if I'm honest :|

I have found the PTO in this rig to be stable, and at some point I'll collect some data.

The power supply was a significant build for me and it took a long time - felt like an apprentice with a master largely on vacation.  The effort paid off - I've had no issues with it.  For PS design I started with the article on RadioBlvd, then found an article on the 'net by Antonio Vernucci, I0JX; both of these have the interconnection leg-work done (for those w/o the dynamotor) and it simplified things.  The unit started off as a Bendix military radar test set and the case, panel and chassis are beefy so I was able to fit in two swinging chokes and transformers as well as the 27v switching PS and variac without bending the chassis.  I filled the panel holes in with JB weld.  The discrete components and relays are under the chassis.  I used all second-hand parts except for diodes, caps and balancing resistors.  (I did splurge on new wire from Remington Industries).  Got the idea for the Meanwell switcher from the Radio Blvd site; it works great, is adjustable, and handles the load surge fine.  So far I haven't noticed any noise from it.  Also small form factor, and $35 online.

One tip I got was to buy a stepped drill bit to drill through the aluminum panel - that thing is a dream, plus the pile of hole bunches I bought from a SK estate.  I also learned a lot about drill bits, and proper drilling technique.

This site helped me with the T17 mic: http://k4che.com/T-17/T-17.htm
My favorite part is the IBM dictaphone footswitch I use to switch the Ant/Dummy Load relay.  That thing is built like a tank.
Logged
Opcom
Patrick J. / KD5OEI
Contributing
Member
*
Offline Offline

Posts: 7462



WWW
« Reply #11 on: December 28, 2019, 02:11:11 PM »



Yes, it is good news.  Having fun with it.  I did the mod to replace the a resistor in the audio section to a lower value for the carbon mic bias - I'm over modulating now, and need to revisit that.

I have a bunch of 813s I've been hoarding and I'll try boosting the B+ a bit and trying some different tubes to see if I can increase the wattage a bit. 
The antenna is tuned to 1.31 SWR @ 3885 and I think that's the best I'll be able to do with my small space. 
Will try again next week after working out some glitches.

By the way, even with receiver muting it's overloading on Xmit which is actually making it easy to spot!
73





What model of scope is that on the left? I think I have the 3" version, very nice mod scope.
Logged

Radio Candelstein - Flagship Station of the NRK Radio Network.
KD2AZI
Member

Offline Offline

Posts: 18


« Reply #12 on: December 28, 2019, 08:42:44 PM »

That's the P&H RF Distortion Indicator model DI-1.  I recapped this, and changed the HV selenium rectifier, and a couple of resistors.  Works fine, I just wish it had a sweep control!
Logged
Opcom
Patrick J. / KD5OEI
Contributing
Member
*
Offline Offline

Posts: 7462



WWW
« Reply #13 on: December 28, 2019, 10:03:46 PM »

That's the P&H RF Distortion Indicator model DI-1.  I recapped this, and changed the HV selenium rectifier, and a couple of resistors.  Works fine, I just wish it had a sweep control!

Oh, I see, I thought it was a Multiphase. Similar logo and good looking!
Logged

Radio Candelstein - Flagship Station of the NRK Radio Network.
KD2AZI
Member

Offline Offline

Posts: 18


« Reply #14 on: December 29, 2019, 08:10:40 AM »

Yep, the CE Multiphase has a sweep control, and one will be on the bench soon.
Logged
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 0.042 seconds with 19 queries.