[Amps] Comparison of PCB-mount RF relays

[Carl]

Jim, great article in QST, that is near the top of my to-do list.

Have you measured make and release times and is there any contact bounce? Im 
wondering about their use as replacements in amps running VOX CW.

Carl
KM1H



----- Original Message ----- 
From: "4CX250B" <4cx250b at muohio.edu>
To: <amps at contesting.com>
Sent: Friday, August 06, 2010 6:33 PM
Subject: [Amps] Comparison of PCB-mount RF relays


>
> ___
>>>>>>> The relays which we use in the Top Ten Devices boxes are 10
>>>>>>> amp,
>>>>>>> sealed power relays.  They are very small and have very low
>>>>>>> inductance.  The contacts are connected to the base pins with
>>>>>>> wide conductors.  I have run many power tests on these relays
>>>>>>> and the pc boards they are mounted on with temperature monitors
>>>>>>> and they will take full amateur power (+) to over 30 MHz.  We
>>>>>>> rate our boxes conservatively at 1.5 KW.  The part number is
>>>>>>> JW1FSN-DC12V.  They come with several different brand names on
>>>>>>> them.  Similar relays are being used by other manufactures of
>>>>>>> amateur boxes and they rate them variously at 3 KW and 5 KW.
>>>>>>>
>>>>>>> George, W2VJN
>
> As Paul W9AC commented earlier I've run some comparison tests of 
> inexpensive PCB-mount power relays in connection with my StationPro 
> controller. The two main contenders were the Tyco/Schrack (also labeled 
> Potter and Brumfield) RTB14012F (rated at 12A DC, and available in a 
> variety of coil voltages), and the JW1FSN-DC12V mentioned by George, 
> above, rated at 10ADC. They are both excellent relays and an amazing 
> value, and each easily handled 2500W at HF, but in the end for HF use I 
> settled on the RTB14012F, based on its internal construction. (Oh, almost 
> forgot. I also tested the relays with a 100% modulated Johnson Desk KW, 
> which produces about 3500W on modulation peaks.)
>
> After sawing the covers off both relays, it became evident the RTB14012F 
> has significantly heavier contacts and shorter strap-like leads to the 
> relays pins than does the JW1FSN-12V. You can see a cutaway photo of 
> RTB14012F  relay on my StationPro website (www.w8zr.net/stationpro/), and 
> if anybody is interested I can post a cutaway photo of the JW1FSN-12V. 
> Both relays have no measurable (by me, anyway) VSWR bump in the StationPro 
> up through 30Mz, and only a 1.2 VSWR at 54MHz. Interestingly, despite its 
> longer internal leads, the JW1FSN-12V shows less VSWR at 146MHz (1.7 vs. 
> 2.0). I attribute its better VHF performance to the coil orientation. It 
> uses a vertically mounted coil, with the contacts beside the coil, whereas 
> the RTB14012F uses a horizontally mounted coil whose magnetic flux lines 
> loop into the contact area. Thus, I suspect the lower mutual inductance 
> between the contacts and the coil are responsible for the slightly better 
> VHF performance of the JW1FSN-12V.  Inciden
> tally, both relays are pin-for-pin compatible with each other and may be 
> freely interchanged. In the StationPro, I recommend the JW1FSN-12V for 
> builders who want to use the unit on 2m, and the RTB14012F for everybody 
> else.
>
> As mentioned in an earlier post, the RTB14012F is also available in a 16 
> Amp version, and I also investigated that relay. Internally it is exactly 
> the same construction as the 12Amp relay, but it has two pins connected to 
> each contact strap, rather than just one pin. Despite this seeming 
> advantage, I can't really recommend the 16 Amp version. Its PCB pin 
> configuration is much more crowded than for the 12 Amp relay, which means 
> one can't use wide PCB traces with it. Also, because of the more closely 
> spaced pins, the 16 Amp version would likely have lower voltage insulation 
> than the 12 Amp relay, which could potentially cause arcing problems when 
> using it with mismatched loads.
> 73,
> Jim W8ZR
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