Warning: Creating default object from empty value in /homepages/11/d132647312/htdocs/Amfone/mkportal/include/SMF/smf_out.php on line 47
Homebrew a plate choke for 4-1000 GG with warc




 
The AM Forum
November 24, 2020, 03:58:09 PM *
Welcome, Guest. Please login or register.

Login with username, password and session length
 
   Home   Help Calendar Links Staff List Gallery Login Register  
Pages: 1 [2]   Go Down
  Print  
Author Topic: Homebrew a plate choke for 4-1000 GG with warc  (Read 1511 times)
0 Members and 1 Guest are viewing this topic.
KD6VXI
Contributing
Member
*
Offline Offline

Posts: 2302


Making AM GREAT Again!


« Reply #25 on: October 27, 2020, 03:20:45 PM »

He should have used one of the big plunger HV contactors.

Plate choke design is an art itself.  I've only begun to understand that statement after building amps and then measuring the chokes in place with the VNA.  Never had a GDO, so this was just one of those "I always used what worked" scenarios.


--Shane
KD6VXI
Logged
VE7RF
Member

Offline Offline

Posts: 34


« Reply #26 on: October 28, 2020, 11:52:03 AM »

He should have used one of the big plunger HV contactors.

Plate choke design is an art itself.  I've only begun to understand that statement after building amps and then measuring the chokes in place with the VNA.  Never had a GDO, so this was just one of those "I always used what worked" scenarios.


--Shane
KD6VXI

I'm seriously  thinking of a  simple   HB  horizontal cam operated plunger setup.   Sorta like a spdt  mini knife  switch.  What else that just might work is a spare  single wafer  model  88  I have packed away.   They are rated for   13 kv  @  60 hz...but that would be marginal..and real  bulky...stray C  etc.

2 x  hb  delrin  plungers, one for each choke would work.   Banana plug on the end of each plunger.   One banana  jack for each choke.   Select  choke  #1...or  choke  #2.

Jim   VE7RF
Logged
KL7OF
Member

Offline Offline

Posts: 2152



« Reply #27 on: October 28, 2020, 12:27:02 PM »

50 uh for testing at 5kv on 17M


* 16039024802281261658875730628839.jpg (3918.61 KB, 4128x3096 - viewed 67 times.)
Logged
VE7RF
Member

Offline Offline

Posts: 34


« Reply #28 on: October 28, 2020, 03:25:43 PM »

50 uh for testing at 5kv on 17M


On paper,  you should experience zero issues.  50 uh should have it's  1st  series  resonance at  40 mhz.
On  3.5 mhz,  50 uh  =    1100  ohms  xl.    5 kv  x .6  =  3 kv       3000/1100 ohms =  2.72  amps  flowing through  the choke..and also the  bypass cap at the base of the  choke.   The bypass cap(s)  should be something substantial to handle  that much current.   Like a pair of  4700 pf  @  10 kv  discs, or what other combo  that will handle 2.72 Amps  @  3.5 mhz.

Even a HEC   HT-57  in  200pf will handle  15A  > 5.2 mhz.....and  12 A  @  3.5 mhz.   And 9 A    at 1.8 mhz.

3.5 mhz  would be the  worse case.  As freq increases, bypass cap  current drops like a rock.... like  1.363 A on 40m...etc.

What gauge magnet wire did you use ?

The  C1  tune cap value will have to be increased  a bit  on  80m.   1100  ohms of  xl  requires   1100 ohms  of  xc  to cancel it out.  IE:  the 50 uh plate choke  will... 'eat'    42 pf from the C1  tune cap.

Jim   VE7RF
Logged
KL7OF
Member

Offline Offline

Posts: 2152



« Reply #29 on: October 28, 2020, 03:33:21 PM »

Bypass caps are 200pf and 500pf at 7.5 kv...choke is 22 ga.wound on delrin?  Mounted 2 inch above chassis on porch insulator..haven,t tried it yet
Logged
KL7OF
Member

Offline Offline

Posts: 2152



« Reply #30 on: November 02, 2020, 08:40:42 PM »

Haven't tested the 50 uh choke yet...got distracted by other stuff...the choke measures 51 uh on the wooden bench and 61 uh installed...Ill post the results...stay tuned....
Logged
Pages: 1 [2]   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 0.052 seconds with 18 queries.