Hi Steve
I have lost 3 of the FET switches.
#1 was on a used 2m PQL built amp that the owner purchased but never used.
It was old, and had the mica insulator on the FET switch instead of the ceramic
one.
The failure was destructive. My thought was that the insulator was at fault.
#2 was the same amp. This one just opened up. No smoke on this one.
I am running the amps directly from the 48v batteries in my trailer. Typically
they run 52v to 55v.
I replaced the FET switch with one of the 65v ones.
I beleive the 50v ones are rated at 30a and the amp draws 28a.
The 65v FET switch is rated at 40a.
I also added another ferrite to the output lead and got them right at the
connection to the FET.
So far this has worked.
#3 was a home built 222 amp using W6PQL parts. It lasted just a few contacts
and some CQs then failed quite spectacularly.
About 1/3 of the board became a charred mass.
I think I didn’t have the screw/insulator that connects the output to the FET
tight enough and it heated up with the high current.
I replaced it and made sure it was tight. All has been good.
Both amps survived MSK144 evenings and mornings over about 30 days on my recent
20 grid rove.
They probably ran 6 hours or more each day of continuous operation.
Jeff
WB8LYJ
> On Aug 6, 2025, at 2:58 PM, Steve Meuse, N1JFU via groups.io
> <smeuse=gmail.com@groups.io> wrote:
>
>
> Dave/Ron, are you using a FET switch on the 50V line? I bough one of the
> W6PQL Fet switches, but I seem to have an issue blowing the FET. I've got
> ferrite on all the DC and control lines, wondering if anyone else has that
> issue?
>
> -Steve
> N1JFU
>
>
> On Wed, Aug 6, 2025 at 11:43 AM Ron Klimas WZ1V <wz1v@sbcglobal.net
> <mailto:wz1v@sbcglobal.net>> wrote:
>> Good Buddy Dave you are the catalyst and top Kielbasa.
>> As usual, a few contacts fall off the edge of
>> my cocktail napkin log while transcribing to email.
>> So KB2KIR makes 23 for me last night.
>> K3SK was much stronger than usual last night.
>> The tropo continued this morning with strong signals
>> from KD4AA and K4RVR FM17.
>>
>> P.S. increasing the voltage to the cooling fans
>> and lowering the bias on the MOSFET gates
>> on the Larcan was a big success,
>> 33 Ohms cut the 50 V by 8 V for 21 V per fan.
>> Originally it was 250 Ohms (as marked and measured).
>> I wound up setting all 4 FETs to 350 ma idling current.
>> Only slightly less than before, but more stable.
>> The amp runs much cooler now even on FT8.
>>
>> 73 Ron WZ1V
>>
>> ----- Original Message -----
>> From: David Olean <k1whs@metrocast.net <mailto:k1whs@metrocast.net>>
>> To: "222 >> 222Activity@groups.io <mailto:222Activity@groups.io>"
>> <222Activity@groups.io <mailto:222Activity@groups.io>>,
>> "vhfcontesting@contesting.com <mailto:vhfcontesting@contesting.com>"
>> <vhfcontesting@contesting.com <mailto:vhfcontesting@contesting.com>>,
>> "NEWSVHF@mailman.qth.net <mailto:NEWSVHF@mailman.qth.net>"
>> <NEWSVHF@mailman.qth.net <mailto:NEWSVHF@mailman.qth.net>>
>> Date: Wed, 6 Aug 2025 07:52:44 -0400
>> Subject: [NEWSVHF] 222 Night Summary K1WHS
>>
>> > Quite a bit of activity on 222 MHz last nite for the weekly gathering of
>> 222 MHz fanatics on a Tuesday night. I made 27 QSOs and managed to work
>> K1FMS twice on FT8 and SSB. I did note that about half of my contacts
>> were at 500 km or more. That is 300 miles or better. There were 13
>> contacts of about 500 km or better, so I guess conditions are looking
>> up. One unusual contact was K3SK at 915 km or about 575 miles on FT8. I
>> think I have only done that once or twice. If I can work Dave K3SK, it
>> is usually Q65B on tropo or via the Moon route which is far easier. An
>> FT8 contact is much more difficult for me.
>>
>> That brings up a point. I seem to not have much success at FT8. Many
>> times I can easily see a trace on the waterfall, but cannot get a
>> decode. It is not due to timing or multi path. I also have been
>> experimenting with narrowing up the passband and have had mixed
>> results. I need to talk with an expert to set me straight. Does MSHV
>> program provide better results?
>>
>> My weekly try with WA3EOQ was successful on CW at 805 km but signals
>> were average (very weak!) Howard runs 95 watts in the shack, so the
>> cntact definitely means that my receiver is not broken! After working
>> K3SK previously at roughly the same heading, I thought that maybe
>> conditions were up. To be fair, K3SK is on the flatlands of Virginia,
>> while WA3EOQ is in the hills of Western MD.
>>
>> I did note with some sadness, tht W7TZ is giving up on 222 EME as his
>> QTH is deluged with local RFI noise which is killing his receiving. He
>> is even using a WD5AGO cavity preamp to minimize RF overload from TV
>> stations etc. I would say that his TX signal on 222 is great off the
>> Moon and he is offering his entire setup at the rock bottom price of
>> about $1200 including his FT736 loaded with bands. Someone in the PNW
>> should snap it up before I drive out there to get it.
>>
>> here is my log from last night. Missing are unsuccessful tries with
>> VA3IKE in EN82 on tropo scatter, along with W7JW on MSK144. W7JWhad 12
>> decodes from me, while I only had two decodes. We quit after 20 minutes.
>> I think my problem is too sharp of an antenna pattern. I need to fix that.
>>
>> ------------------------------------------------------------------------------------------
>> DATE TIME CALLSIGN LOCATOR TX RX BAND MODE
>> PRO.REMARKS QRB
>> -------------------------------------------------------------------------------------------
>> 08/05/2025 22:40 KA2ENE FN13FE -04 -05 220 MHzFT8
>> TR 533
>> 08/05/2025 22:50 K1FMS FN32QB +24 +17 220 MHzFT8
>> TR 201
>> 08/05/2025 22:58 K1FMS FN32QB 59 59 220 MHzSSB
>> TR 201
>> 08/05/2025 23:01 KA3FQS FN2ØJF 59 220 MHzSSB
>> TR 498
>> 08/05/2025 23:03 WW1Z FN42ET 59 59 220 MHzSSB
>> TR 84
>> 08/05/2025 23:08 KB2KIR FN22EN ` 220 MHzSSB
>> TR 391
>> 08/05/2025 23:13 WW1Z FN42ET 59 59 220 MHzSSB
>> TR 84
>> 08/05/2025 23:25 W8ZN FMØ9TE 539 559 220 MHzCWK
>> TR 776
>> 08/05/2025 23:36 K2AEP FN32OW 539 220 MHzCW
>> TR 157
>> 08/05/2025 23:46 K3SK FMØ7TJ -18 -16 220 MHzFSK
>> TR 915
>> 08/05/2025 23:50 W2BYP FN13IB +7 220 MHzFSK
>> TR 514
>> 08/05/2025 23:52 NZ3M FN1ØPD -06 -14 220 MHzFSK
>> TR 598
>> 08/05/2025 23:53 N1SV FN42BL +32 -15 220 MHzFSK
>> TR 126
>> 08/06/2025 00:02 K1PXE FN31 +32 220 MHzSSB
>> TR 265+-
>> 08/06/2025 00:03 K2RMX FN2ØXE 57 220 MHzSSB
>> TR 439
>> 08/06/2025 00:05 K1RZ FM19JH 559 549 220 MHzCW
>> TR 691
>> 08/06/2025 00:06 W1AUV FN32II 559 220 MHzCW
>> TR 223
>> 08/06/2025 00:10 WA3NUF FN2ØKE +16 +15 220 MHzFT8
>> TR 496
>> 08/06/2025 00:13 W9KXI FN12NE -08 -08 220 MHzFT8
>> TR 501
>> 08/06/2025 00:15 N3ITT FN2ØKL -00 -02 220 MHzFSK
>> TR 473
>> 08/06/2025 00:19 WA1PBU FN42EK -00 220 MHzSSB
>> TR 120
>> 08/06/2025 00:26 N3RG FM29KI -55 59 220 MHzSSB
>> TR 568
>> 08/06/2025 00:30 W1XIV FN34JJ -55 220 MHzSSB
>> TR 212
>> 08/06/2025 00:33 W1AIM FN34 59 59 220 MHzSSB
>> TR 203+-
>> 08/06/2025 00:39 K1BX FN43EB 59 220 MHzCW
>> TR 65
>> 08/06/2025 00:41 WA3EOQ FMØ9JO 59 220 MHzSSB
>> TR 805
>> 08/06/2025 00:45 KC2SGV FM29FN 59 220 MHzSSB
>> TR 572
>> 08/06/2025 00:45 WB2RVX FM29MT 59 220 MHzSSB
>> TR 519
>> -------------------------------------------------------------------------------------------
>> Number of QSO listed: 28
>>
>> 73
>>
>> Dave K1WHS
>>
>> ps. We are awaiting news from the 222 MHz Activity Committee on who
>> might possibly win the properly aged Kielbasa from Chiciopee, Massachusetts.
>>
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>
>
> --
>
> -Steve
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