[Amps] Kilovac relay in MFJ 2020 catalog

[Jim Thomson]

##  Alpha, back  years  ago,  used a RJ1A.   They  later  switched to  the 
Kilovac  HC-1...which  has  more  robust insides..esp  for  QSK  CW...lasts 
a  lot  longer.
The  gigavac GH1  is  superb..and  consistently  Hi-pot  tests  to >  7.5 
kv.   The  GH1  is  the  best  of  the  3.    All  3  look  identical .

##  Kilovac  told  me  the  speed  up  circuits  with the  overvoltage, 
with  or  without  the  cap  across the  drop  resistor   will  not  degrade 
the  relay  life.

##  Buddy  uses  3 x gigavac GH1s   on  his  2 x GS35B    6M monoband  amp. 
Input,  output,  and  cutoff  bias.   Handles   4.7  kw  just  fine  for 
the  last  8  years.

##  The  sped up  gigavac G2s ended  up  with  2-3  bounces..  but  still 
were  2.5  to  2.7  msecs.....including  bounces.   Used  on a  YC-156 
amp..and  also a 3x6  amp.
The  YC-156  80-10  amp  gets  the QSK  work out  on a regular basis.

Jim   VE7RF



-----Original Message----- 
From: Jim Garland
Sent: Thursday, February 20, 2020 4:27 PM
To: 'Jim Thomson' ; amps at contesting.com
Subject: RE: [Amps] Kilovac relay in MFJ 2020 catalog

I've long wondered whether these speed-up circuits that pulse vacuum relay 
coils with an overvoltage also exacerbate contact bounce and possibly 
shorten the relay life. Intuitively that seems reasonable, though I've not 
taken any data to check out the possibility. A few years ago, I wrote up my 
personal QSK design and some of the accompanying relay data for QST (June 
2015, and http://www.w8zr.net/QSK/). and at the time looked at the switching 
characteristics of numerous vacuum relays. I found a wide variation in the 
amount of contact bounce. The Gigavac G41C, used in the Alpha 9500, 
typically had a half dozen or more bounces before the contacts settled down. 
That was a particularly noisy relay, with an audible twang when the movable 
contact slammed into its mating contact. The best relay, bounce-wise, was 
the Jennings RJ1A, which switched in about 2 msec, was nearly silent, and 
showed no bounce. There are various clones of the Jennings design, but I 
didn't check any of them. On the basis of the data, I chose the RJ1A for my 
"contest-rated" 160/80m duoband amplifier, and it's been great. (It's 
probably not hefty enough for the upper HF bands in that kind of 
application.)
73,
Jim W8ZR

> -----Original Message-----
> From: Amps [mailto:amps-bounces at contesting.com] On Behalf Of Jim Thomson
> Sent: Thursday, February 20, 2020 08:51 AM
> To: amps at contesting.com
> Subject: [Amps] Kilovac relay in MFJ 2020 catalog
>
> Date: Wed, 19 Feb 2020 09:28:37 -0600
> From: Jim <jimw7ry at gmail.com>
> To: amps at contesting.com
> Subject: Re: [Amps] Kilovac relay in MFJ 2020 catalog
>
> <Depends on how fast the relay is. Just because its vacuum, doesn't mean
> <its fast!
>
> <I use solid state relays for cathode switching now days. Works great.
>
> <73
> <Jim W7RY
>
> ##  an  opto isolator  works,  along  with  its 4  kv  isolation.  Problem 
> is,  I  typ
> use  60-120  vdc  OCV  for  the  sped  up  26.5  vdc  vac TR relays....  + 
> drop
> resistor..+  small  cap  across  drop  resistor.   Kilovac  told  me 
> years ago,  that
> if  voltage  limited,,  like  only  24 –27 vdc  available,  use vac 
> relays  with 12 vdc  coils.
>
> ##  Buddy  and  I  managed   to  speed  up a gigavac G2.....same  as a 
> jennings RJ2B.
> Rated  for  15 msecs   operate...and  9  msecs  release.   Sped  up,  with 
> 80  vdc
> and a .5uf  cap  across   drop  resistor,   they  become   2.5 msecs 
> operate..and  rls.
> 2nd  G2  was  2.7  msecs  operate  and  rls.   26.5 vdc  rated coils.
>
> ##  Both  G2s  were  individually tested on  bench.  Then  installed  in 
> GG  triode  amp,
> on  output  side,  with  all  contacts in  parallel.   Fast  enough  for 
> QSK,  and  good  for
> 20A  CCS  at  32 mhz.
>
> ## Ameritron  sez their  kilovac relay can be used  in  QSK.   Dunno  how 
> u can  do  that
> with a DPST relay.  Normally a DPDT  is  used...  or a SPDT  on   both 
> input +  output.
>
> ##  I  might  buy one....just  to  test on  the  bench....since  they  are 
> cheap.
>
> Jim  VE7RF
>
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