[Top] [All Lists]

Re: [Amps] Kilovac relay in MFJ 2020 catalog

To: "Jim Garland" <>, <>
Subject: Re: [Amps] Kilovac relay in MFJ 2020 catalog
From: "Jim Thomson" <>
Date: Fri, 21 Feb 2020 07:06:28 -0800
List-post: <>
## 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' ;
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 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.)
Jim W8ZR

-----Original Message-----
From: Amps [] On Behalf Of Jim Thomson
Sent: Thursday, February 20, 2020 08:51 AM
Subject: [Amps] Kilovac relay in MFJ 2020 catalog

Date: Wed, 19 Feb 2020 09:28:37 -0600
From: Jim <>
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.

<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

Amps mailing list

Amps mailing list
<Prev in Thread] Current Thread [Next in Thread>