The AM Forum
March 29, 2024, 01:50:15 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: My current transmitter project  (Read 7964 times)
0 Members and 1 Guest are viewing this topic.
wd8das
Member

Offline Offline

Posts: 167


« on: August 17, 2013, 05:05:46 PM »


Here are some photos of the early 1960s vintage Gates BC-1T AM broadcast transmitter I've been working on lately... 

http://www.flickr.com/photos/32025136@N03/sets/72157635109428347/

I've got my first Gates that I acquired a few years ago positioned to the left along the wall, and this new second one is to the right.   I converted the first rig to 160 meters, and this one will be on 75 meters when I'm done.  Right now I've got it all back together and restoration is complete - it is running smoothly with a kilowatt output into a dummy load at its original 1400 kHz.  I've also added the various step-starts, silent contactors, PTT and antenna switching, and other mods to make it much like the other rig.  Next step is to move it up to 3885 kHz.

This second rig was in better physical condition than my first, for two reasons.  (a) it was a one-owner rig kept in a nice transmitter building.  (b) I hosed the dust out of it in the driveway.  The first one was much dirtier and more corroded due to (a) being a twice handed-down unit abandoned in a tumbledown "shack", and (b) it was a wintertime project so I did not have the option of washing it out with the hose before bringing it into the house.

You can see photos of my earlier BC-1T project for 160 meters on my website at

http://www.wd8das.net/gates.html

A summary of my mods for the BC-1T can be found at

http://www.wd8das.net/Gates/GatesNotes.pdf


Steve WD8DAS

http://www.wd8das.net/
--------------------------------------------------------------------
Radio is your best entertainment value.
--------------------------------------------------------------------
Logged
wd8das
Member

Offline Offline

Posts: 167


« Reply #1 on: August 17, 2013, 09:34:11 PM »


Maybe I should get one more BC-1T to put on 475 kHz CW.

Steve WD8DAS

Logged
W3GMS
Contributing
Member
*
Offline Offline

Posts: 3063



« Reply #2 on: August 17, 2013, 09:52:56 PM »

Fantastic pictures Steve.  Your original one looks better than a lot of the other ones I have seen.  Very nice job and I enjoyed looking at all your pictures and technical notes on the project.  As you mentioned the second one is very clean. 

I  have an early 40's Gates 250C1.  One will land on 160 and the other one will either be on 40 or 80.  They do go on 40 without much trouble.  The final is a pair of 810 in PP modulated by a pair.  Both of mine were frame off restorations.  One I did with the help of a friend and the other I bought already restored. 

73,
Joe, W3GMS         
Logged

Simplicity is the Elegance of Design---W3GMS
wd8das
Member

Offline Offline

Posts: 167


« Reply #3 on: August 19, 2013, 01:50:03 AM »

Thanks, Joe.  Nice to have a rig that can go to 40 smoothly.  I don't think this model will go to 40 without some serious rethinking of the output network physical arrangement.  Output network placement should be ok on 75, though - just less of each piece of it. 

I think I've got the whole move to 75m mapped out now.  I'd already modified a spare oscillator module for the higher frequency and put crystals in it for 3880 and 3885, plus a VFO input, so that's all tested and working.  The RF driver/PA grid coil is the oddest part due to the neutralization scheme but I think I can scale it down from both ends to get to the higher band without losing the place to introduce the feedback from the plate. 

Steve WD8DAS
Logged
wd8das
Member

Offline Offline

Posts: 167


« Reply #4 on: August 29, 2013, 11:57:24 AM »


I've completed the Gates BC-1T restoration and conversion to 75m. 
Here are photos of my two Gates transmitters side by side in the shack...

http://www.wd8das.net/shack.jpg
http://www.wd8das.net/Gates/2rigs.jpg

The newly restored and converted 75m rig is on the right.

Additional photos

http://www.flickr.com/photos/32025136@N03/sets/72157635109428347/

Steve WD8DAS



Logged
KA0HCP
Contributing
Member
*
Offline Offline

Posts: 1188



« Reply #5 on: August 29, 2013, 01:05:52 PM »

Well thought out mods. Nicely done!
Logged

New callsign KA0HCP, ex-KB4QAA.  Relocated to Kansas in April 2019.
Opcom
Patrick J. / KD5OEI
Contributing
Member
*
Offline Offline

Posts: 8308



WWW
« Reply #6 on: August 29, 2013, 11:16:48 PM »

Those are beautiful transmitters and you have kept the looks straight not ham'ed up, that's great!

It always seems like the iron esp the mod. transf. and mod. choke in these newer BC rigs is physically much more compact than in the old stuff, yet the performance is there. Are those hypersil, or have been upgraded to newer parts?

Way more compact than the '40's stuff for example I have no real room for an old style  modulation choke and have to do without. No space in the floor of my TX despite the same 'wide' size cabinet.
Logged

Radio Candelstein - Flagship Station of the NRK Radio Network.
W3GMS
Contributing
Member
*
Offline Offline

Posts: 3063



« Reply #7 on: August 30, 2013, 08:54:13 AM »


I've completed the Gates BC-1T restoration and conversion to 75m. 
Here are photos of my two Gates transmitters side by side in the shack...

http://www.wd8das.net/shack.jpg
http://www.wd8das.net/Gates/2rigs.jpg

The newly restored and converted 75m rig is on the right.

Additional photos

http://www.flickr.com/photos/32025136@N03/sets/72157635109428347/

Steve WD8DAS





Steve,
Glad you have everything working.  Twin BC transmitters side by side has a very "special" look!  I have a pair of restored Gates 250C1's and that is the plan to put them next to each other.  One will be on 160 and the other will either be modified to  go on 80 or 40.  I have not decided that detail yet, but I am leaning to put the second one on 80M. 

Here is a picture of my second 250C1. 

Joe, GMS     


* IMG_0918.JPG (2877.69 KB, 3240x4320 - viewed 562 times.)
Logged

Simplicity is the Elegance of Design---W3GMS
N4LTA
Contributing
Member
*
Offline Offline

Posts: 1075


« Reply #8 on: August 30, 2013, 12:40:58 PM »

Good looking Transmitter!

"Maybe I should get one more BC-1T to put on 475 kHz CW."

It's a little larger than my 1 KW Class D transmitter on 475 KHZ though

Pat
N4LTA
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 0.061 seconds with 18 queries.