Hi Stefan,
and thank you for effort and suggestion :-)
Indeed carefully checking while testing I found what was going wrong
beyond 30Vdd of supply to FETs: the xfmr between the IXDD stage and
gates became very hot!!
Nothing up to 30Vdd but then.. xfmr warm and degradated wave forms!
The xfmr was wound on a little binocular form made of N30 material and
I replaced it with a BN43-202 increasing the number of turns (total
inductance a bit more than 1mH) and everything was solved and PA now is
almost ready to go to the final intended supply of 180Vdc.
The tank coil, made of 1,5mm² wire was then warming, and yesterday I
made a new, bulky, coil with 2,5 mm² which also get warm (abt 60°C)
melting the hot melt glue used to fix to the chassis... so now some
mechanical artwork for new support without hotmelt glue...
Marco IK1HSS
----Messaggio originale----
Da: [email protected]
Data: 5-giu-2017 11.18
A: <[email protected]>
Ogg: Re: R: Re: R: Re: LF: Re: I: Fw: For today the FETs survived...
Hello Marco,
I was unable to write a longer text for a few days (no desktop PC
available, just the smartphone and Teamviewer) so my answer is a bit
late. You've got a lot of advice since that time.
I'm just adding what came to my mind...
-I assume you already checked that the supply voltages stay constand
in
any working point.
-The gate voltages are important. Also the duty cycle should be
constant
and close to 50% for best operation.
In my H bridge PA for 137 kHz the gate voltage is +- 8V, quite a
rectangular waveform. Unfortunately i have no scope captures quickly
available.
-Try to lower the 4 Ohm resistor after the IDXX driver. It is there to
avoid oscillations after the switching slopes. Maybe 2 Ohm is enough.
-Even more important: Make sure the transformer is wound for a minimum
stray inductance because this will quickly lead to strong
oscillations.
Wind all the 3 windings equally spread arround the whole core
(ferrite,
e.g. N30, AL>2000nH). Wind them trifilar, not separated.
If there are still problems show us images of: The gate source
voltage,
the gate drive transformer.
73, Stefan
Am 03.06.2017 16:44, schrieb [email protected]:
> Hi Stefan,
>
> and thank you :-) so you have too something to mumble while sending
> VLF SMS ;-)
> There is nothing really new.. I started from an avalable
> chassis with on board a PS giving 180Vdc (1200W) and assembled the
> Andy's half bridge 700W switching PA and before give it the full
power
> I'm checking with lower DC supply. Attached you see the schematic
with
> some change at the moment..
> The output xfmr has 7T/19T, the coil of the guard circuit is not
> connected (now is in serie with L2) and the resonating caps now are
> 5x1000pF in parallel.
> The aim is finally with 180Vdc of supply have an output of 0,5÷1kW
> but.... as you probably red in the previous messages, from 10 to
30Vdc
> the PA runs, at low power of course (up to 15W), and complies the
> calculations; with supply between 30 and 50 Vdc the output go down to
a
> couple of W.
> I made several trials it the last days, changing the core of the
xfmr,
> the turn ratio, the kind of capacitators but nothing changes (or at
> least the change are within a fraction of dB).
>
> that's the sad history Stefan...
> All thoughts and suggestions are welcome! (including go to fish ;-))
)
> Marco
>
> ----Messaggio originale----
> Da: [email protected]
> Data: 3-giu-2017 16.19
> A:<[email protected]>
> Ogg: Re: R: Re: LF: Re: I: Fw: For today the FETs survived...
>
> Hi Marco,
>
> If you like, i can help you. Just need a schematic to see what you
> want
> to do. Targer power, voltage, etc...
>
> 73, Stefan
>
> Am 03.06.2017 16:02, schrieb [email protected]:
>
>> Hi Alan, Andy, Chris,
>>
>> I replaced the caps in the output LC with WIMA FKP1, the 2 caps wich
>> replaces the missing half of the bridge are still Cornell Dubillier
>> 940C serie (rated at 9A @100kHz), so now all the caps are pulse
rated
>> but...
>> I regret to admit it, nothing changed :-((
>> Power out increases from 10 to 30Vdc and at 40Vdc after a first
pulse
>> the power slowly decreases till a couple of watts..
>>
>> Just to check another thing: being the coil of the guard circuit
>> disconnected, I jointed the 2 coils together (they are wound on the
>> same support) increasing so the inductance of the L (25T more). Of
>> course I had to retune and now I need C in the range of 5000pF but
>>
> this
>
>> narrowed the 3dB bandwidth of the LC from abt 15kHz to abt 8kHz so
is
>> the Q increased!
>>
>> ... I should visit Decathlon and look for a fishing rod!
>>
>> your sincerely depressed IK1HSS
>>
>> ----Messaggio originale----
>> Da: [email protected]
>> Data: 2-giu-2017 15.58
>> A:<[email protected]>
>> Ogg: Re: LF: Re: I: Fw: For today the FETs survived...
>>
>> Hi Marco, I may well be wrong I was experimenting with 150W at 35V I
>> measured 12 to 15A through the capacitors (from memory) .......the
>> confirmation is that the change is permanent. I dont remember seeing
>> any
>> heating effects. Single ended Class E may be considerably different
>>
> to
>
>> H-bridge. The currents a lower power will be less, about 1.5A or so
>> (??) I
>> am not sure it that would produce damage, but you would certainly
see
>> it as
>> the power increased.
>>
>> Good Luck with it
>> Alan
>> G3NYK
>>
>> ----- Original Message -----
>> From:<[email protected]>
>> To:<[email protected]>
>> Sent: Friday, June 02, 2017 2:00 PM
>> Subject: R: LF: Re: I: Fw: For today the FETs survived...
>>
>>
>> Hi Alan,
>>
>> and thanks for joining :-)
>> it's hard to believe at this stage that is correct to speak of "high
>> currents"..
>> The PA is an half bridge like
>> Andy's 700W but now I'm testing at low voltage: I see these problem
>> trepassing the 30Vdc supply level (and power is about 15W)..
>> Anyway will try with the "pulse rated caps" you suggested just in
>>
> case
>
>> my "low current" "low tension" ideas are wrong.
>> 73 Marco
>> ----Messaggio originale----
>> Da: [email protected]
>> Data: 2-giu-2017 14.36
>> A:<[email protected]>
>> Ogg: LF: Re: I: Fw: For today the FETs survived...
>>
>> Hi Marco I dont know where you are putting the caps but I am
assuming
>> they
>> are passing a high RF corrent. I found that the old style (valve)
>>
> high
>
>> voltage caps in my Class E test rig changed capacitance permanently
>> during
>> and after a run (capacitance reduced). I assumed that the current
was
>> fusing
>> the foil connection to the lead-out wires. When using "pulse rated"
>> capacitors as used in SMPSUs I had no further capacitance change
>> problems.
>> The ones I have are RIFA PHE 428 2000v from RS Components. I think
>> Farnell
>> do a WIMA equivalent.
>>
>> Best Wishes
>> Alan
>> G3NYK
>>
>> ----- Original Message -----
>> From:<[email protected]>
>> To:<[email protected]>
>> Sent: Friday, June 02, 2017 1:06 PM
>> Subject: R: Re: Re: Re: LF: Re: I: Fw: For today the FETs
survived...
>>
>>
>> now my thoughts are even more confused....
>> Hi Andy, me again....
>> after a long night of meditation, I remembered I had a bounch of old
>> style mica capacitators 1000pF 1000V..
>> I put
>> 9 of them in parallel to get the closer value to the 8800pF I had
>> before.
>> Of course the resonance moved a bit and now is on 134.5 kHz with 3dB
>> bandwidth of 9 kHz (Q=15 I know is a bit to high..) so carried out
>>
> some
>
>> tests on 134 kHz (of course on the dummyload) all without guard
>>
> circuit
>
>> 1st test xfmr 7T/19T (Ae197mm² R50 mat T38): 2Wout @10Vdc; 6,5
>> Wout@20Vdc; 13,7Wout@30Vdc stable.. @40Vdc after a quick peak the
>>
> power
>
>> slowly goes down till below 1W!
>> 2nd test I had still on hands the previous xfmr 5T/12T (Ae197mm²
same
>> core as 1st test) so was worth to make a trial... same trend :-( for
>> Vdc> 30V after a first peak... it goes down.
>> I had another core available with different material (N30, Ae 154mm²
>> R58) so I prepared a new xfmr with this core 7T/14T:
>> 1,4Wout@10Vdc; 4,6Wout@20Vdc; 9,2Wout@30Vdc .... at 40Vdc a short
>>
> burst
>
>> with almost 15Wout and then down down down... :-((((((
>>
>> I noticed a difference in comparison to your project: you connected
>>
> the
>
>> + and - rails to ground via 10nF and here I used 100nF caps could it
>> explain this behaviour?
>>
>> 73 Marco
>>
>> ----Messaggio originale----
>> Da: [email protected]
>> Data: 1-giu-2017 22.20
>> A:<[email protected]>
>> Ogg: R: Re: Re: Re: LF: Re: I: Fw: For today the FETs survived...
>>
>> that was also my thought.. but they run at room temperature: the
>> resonance is obtained with 4 polyesther 2200 pF 2000 Vdc caps. the
>> classic boxes 25x15x5mm
>>
>> Marco
>>
>> ----
>> Messaggio originale----
>> Da: [email protected]
>> Data: 1-giu-2017 22.03
>> A:<[email protected]>
>> Ogg: Re: Re: Re: LF: Re: I: Fw: For today the FETs survived...
>>
>> If the conditions change as the PA is operating, it looks like
>> capacitors
>> heating up and changing its value. I can't think of any other
>> component
>> that will change with dissipation / heating. What type of capacitor
>> are
>> you using in the tank?
>>
>> Andy
>>
>>
>> On 1 June 2017 at 19:59, [email protected]<[email protected]>
>> wrote:
>>
>>
>>
>>> anybody has good ideas for a replacement hobby?? fishing? growing
>>> flowers?
>>>
>>> Andy: the suggestion of try without the guard circuit revealed that
>>> some effects in this area are present.
>>>
>>> I left the guard coil in place (I'm a bit lazy...) and disconnected
>>> simply the 2 wires from the rectifier bridge.
>>> The output improve of about 4dB with Vdd from 10 to 30V, the output
>>>
>>>
>> is
>>
>>
>>> stable up to 20Vdd, on 30V it show a peak of 16W, then the output
>>> starts to decrease till a couple of watts :-( this happens also at
>>>
> 40
>
>>> and 50V.
>>> The resonance of the output LC (with the guard coil open) shifts
>>>
> from
>
>>> 137 to 140 kHz and the bandwidth decreases from 20kHz to 10 kHz.
>>>
>>> I need a long weekend of meditation...
>>> 73 Marco IK1HSS
>>>
>>>
>>> ----Messaggio originale----
>>> Da: [email protected]
>>> Data: 31-mag-2017 21.05
>>> A:<[email protected]>
>>> Ogg: R: Re: Re: LF: Re: I: Fw: For today the FETs survived...
>>>
>>> Andy.. you are almost better than online help desks :-D
>>>
>>> yes the guard circuit is on place but no current is flowing toward
>>>
>>>
>> the
>>
>>
>>> PA, testing disconnetting it needs just to warm up the iron ;-)
>>>
>>> the PS should
>>> provide enough juice for 1200W input and the IRF460A are rated for
>>>
>>>
>> 20A
>>
>>
>>> @ 25°C (13A @ 100°C) so.. I admit it would like to give a try ;-)
>>>
>>> I don't guess the core is saturating specially at this power level
>>> where rms is only 22V, the core is 50mm OD and has 195,7 mm²Ae: if
I
>>> am
>>> not totally wrong B should be< 0,03T @50V with 7 turns on the
>>>
>>>
>> primary
>>
>>
>>> Will tru to disconnect the guard circuit just in case the squirrel
>>>
> is
>
>>> running in its cage ;-)
>>>
>>> Thanks again for assistence
>>>
>>> Marco IK1HSS
>>>
>>>
>>>
>>> ----Messaggio originale----
>>> Da: [email protected]
>>> Data: 31-mag-2017 20.39
>>> A:<[email protected]>
>>> Cc:<[email protected]>
>>> Ogg: Re: Re: LF: Re: I: Fw: For today the FETs survived...
>>>
>>> 7:19 turns (assuming 50R output) means you have a load resistance
>>>
> of
>
>>> 6.8
>>> ohms which for 180V DC (81 V RSM fund sine) is nearly 1kW I don't
>>> think
>>> you really mean to go that extreme do you? 13 ohms is more
>>> realistic.
>>>
>>> As for the tank resonance changing as power increases, that is very
>>> wrong.
>>> I wonder if the transformer is saturating. Not sure of your core
>>>
>>>
>> Ae,
>>
>>
>>> but
>>> lets assume 200mm square, a core of about 16mm diameter.
>>>
>>> V = 4.44.F.N.A.B Plugging in 137kHz 7 turns, 200 mm^2 and a Bmax
>>>
>>>
>> of
>>
>>
>>> 0.1
>>> that suggests 85V RMS.
>>> Which is exactlyly what you have. I suggest more primary turns .
>>> Before
>>> a transformer ratio of 1:2 was suggested, for Rload = 13 ohms
>>>
>>> Is the guard circuit in place ? Don't forget, it has to be
>>> customised
>>> to
>>> you exact currents and coil Q. Get teh PA operating to its proper
>>> settings
>>> foirst - that you can do at low voltage power, it scales perfectly.
>>> Only
>>> when it it working properly can you add and set up the guard
>>>
> circuit.
>
>>> When I did teh 700W PA, I had a complete workign (albeit
unreliable)
>>> unit
>>> before even thinking of teh guard circuitry.
>>>
>>> Andy
>>>
>>>
>>>
>>>
>>>
>>> On 31 May 2017 at 18:50, [email protected]<[email protected]>
>>> wrote:
>>>
>>>
>>>
>>>> Hi Andy... me again...
>>>>
>>>> I was so curious to see what could happen thatI had a very quick
>>>> dinner and connected all, but...
>>>>
>>>> now the output xfmr has 7T/19T here my
>>>> readings/calculations:
>>>> (see attached picture)
>>>> again the power increase from 10 to 30Vcc then from 30 to 50Vcc
>>>>
>>>>
>> after
>>
>>
>>>> an initial burst it start to fall down..
>>>> I checked also the resonance of the LC: till 30Vcc is tuned on 137
>>>>
>>>>
>>> kHz
>>>
>>>
>>>> with a 3dB bandwidth of 20 kHz, when I move to 40 and 50Vcc the
>>>> "maximum" output shifts to 165 kHz...
>>>>
>>>> mumble mumble
>>>>
>>>> I tempted to have roasted FETs for dessert and see what happens at
>>>> 180V!
>>>>
>>>> Marco, IK1HSS
>>>>
>>>>
>>>> ----Messaggio originale----
>>>> Da: [email protected]
>>>> Data: 30-mag-2017 23.50
>>>> A:<[email protected]>
>>>> Cc:<[email protected]>
>>>> Ogg: Re: LF: Re: I: Fw: For today the FETs survived...
>>>>
>>>> I've just looked again at the circuit diagram you sent - on there
>>>>
>>>>
>> the
>>
>>
>>>> values are different from your statement in the email. It shows
>>>> primary 5
>>>> turns, secondary 12 turns so a load resistance in the order of 9
>>>>
>>>>
>> ohms
>>
>>
>>>> which
>>>> is rather low if you are intending a Vdd of 180V - but closer to
>>>>
>>>>
>> the
>>
>>
>>>> ideal
>>>> Rl
>>>>
>>>> The tank components have a reactance of 130 ohms which is too high
>>>>
>>>>
>> a
>>
>>
>>> Q
>>>
>>>
>>>> is
>>>> used with that 9 ohms Rload, You should be aiming for a Q in the
>>>>
>>>>
>>> region
>>>
>>>
>>>> of
>>>> 6.
>>>>
>>>> Even with the optimum load R of 13 ohms described last time for
500
>>>> Watts
>>>> from 180V rail the resulting Q of 10 is a bit too high - you will
>>>>
>>>>
>> end
>>
>>
>>>> up
>>>> with high voltage and critical tuning
>>>>
>>>> Andy G4JNT
>>>>
>>>> On 29 May 2017 at 19:07, Andy Talbot<[email protected]>
wrote:
>>>>
>>>>
>>>>
>>>>> Yes.
>>>>> As you'll see in my original write up, I originally forgot that
>>>>>
>>>>>
>> the
>>
>>
>>>> peak
>>>>
>>>>
>>>>> of the fundamental sine component of a square wave is GREATER
>>>>>
>>>>>
>> than
>>
>>
>>>> the peak
>>>>
>>>>
>>>>> by a factor of 4 / pi and initially my PA delivered a lot more
>>>>>
>>>>>
>>> power
>>>
>>>
>>>> (1.6
>>>>
>>>>
>>>>> times) than it was supposed to.
>>>>>
>>>>> So if the square wave has a peak value of 1, its fundamental sine
>>>>> component has a peak value of 4/pi or around 1.27. The RMS of
>>>>>
>>>>>
>> the
>>
>>
>>>>> resulting sine is SQRT(2) less than this giving a Peak square to
>>>>>
>>>>>
>>> RMS-
>>>
>>>
>>>> sine
>>>>
>>>>
>>>>> ratio of 0.9.. If you specifye peak-peak of the square wave, a
>>>>>
>>>>>
>>>> further
>>>>
>>>>
>>>>> factor of 2 applies, leading to the 0.45 ratio described before.
>>>>>
>>>>> Incidentally, this same ratio appears in that equation for flux
>>>>>
>>>>>
>>> in
>>> a
>>>
>>>
>>>>> magnetic code, V = 4.44.F.N.A.B
>>>>> The magic number 4.44 is actually SQRT(2) * pi and comes
>>>>>
>>>>>
>> about
>>
>>
>>>> from
>>>>
>>>>
>>>>> the same sort of sine to square transform.
>>>>>
>>>>> Andy
>>>>>
>>>>> On 29 May 2017 at 18:48, [email protected]<marcocadeddu@tin.
>>>>>
>>>>>
>> it>
>>
>>
>>>> wrote:
>>>>
>>>>
>>>>>
>>>>>
>>>>>> uhuh... a slightly silly misleading assumption... Vdc are the
>>>>>>
>>>>>>
>> same
>>
>>
>>>> of
>>>>
>>>>
>>>>>> Vrms before FETs make their work!
>>>>>>
>>>>>> Thank you Andy for pointing out it!!
>>>>>> With this approach calculation changes a bit and probably with
>>>>>>
>>>>>>
>> the
>>
>>
>>>>>> right Xfmr the PA can give higher satisfaction :-)
>>>>>>
>>>>>> Hopefully the FETs will survive and this time I'm ready to
>>>>>>
>>>>>>
>> burnout
>>
>>
>>>> the
>>>>
>>>>
>>>>>> antenna hi
>>>>>>
>>>>>> Will keep you both updated, thank you once more Andy
>>>>>>
>>>>>> 73 Marco, IK1HSS
>>>>>> ----Messaggio originale----
>>>>>> Da: [email protected]
>>>>>> Data: 28-mag-2017 21.18
>>>>>> A: "[email protected]"<[email protected]>,
>>>>>> <[email protected]>
>>>>>> Cc:<[email protected]>
>>>>>> Ogg: LF: Re: I: Fw: For today the FETs survived...
>>>>>>
>>>>>> First thing I noticed is that your turns ratio on the output
>>>>>> transformer
>>>>>> doesn't look right.
>>>>>> You quote "* ... with primary winding of 15 turns and secondary
>>>>>>
>>>>>>
>> of
>>
>>
>>>> 12
>>>>
>>>>
>>>>>> turns...*"
>>>>>>
>>>>>> 180V DC in a half bridge is 180V peak-peak square wave.
>>>>>> The fundamental sine part of that is 4/pi * 180 = 229V pk-pk
>>>>>> so is 229V /[2.SQRT(2)] = 81V RMS
>>>>>>
>>>>>> To a good approximation RMS(fund) from a half bridge is Vrms
>>>>>>
>>>>>>
>>> (fund)
>>> =
>>>
>>>
>>>>>> 0.45VDC
>>>>>>
>>>>>> For 500 Watts out, Rload = 81 ^ 2 / 500 = 13 ohms
>>>>>>
>>>>>> So to match to 50 ohms you need a turns ratio of SQRT(50/13) =
>>>>>>
>>>>>>
>>> 1.9:
>>>
>>>
>>>>>> 1 so
>>>>>> call it 2:1 Keeping 12 turns on the secondary means you need 6
>>>>>>
>>>>>>
>>>> turns
>>>>
>>>>
>>>>>> on
>>>>>> the primary
>>>>>>
>>>>>> When operating at reduced voltage, the power out will vary
>>>>>>
>>>>>>
>> exactly
>>
>>
>>>> as
>>>>
>>>>
>>>>>> the
>>>>>> square of the voltage.
>>>>>> Recalculating from first principles for a 12V supply:
>>>>>>
>>>>>> 12V DC = 12V pk-pk = 12 / [2.SQRT(2)] * 4/pi = 5.4V RMS
>>>>>>
>>>>>>
>>>> (fundamental)
>>>>
>>>>
>>>>>> in 13 ohms should give 5.4^2/13 = 2.2 Watts
>>>>>>
>>>>>> check using ratio of voltages, squared :
>>>>>>
>>>>>> (12V/180V) ^ 2 * 500W = 2.2 Watts which is the same as above.
>>>>>> QED
>>>>>>
>>>>>> Your 15:12 ratio result sin a load impedance of (15/12)^2 * 50 =
>>>>>>
>>>>>>
>>> 78
>>>
>>>
>>>>>> ohms
>>>>>>
>>>>>> At 40V DC == 18V RMS(fund) that will give 18^2/78 = 4.1 watts
>>>>>>
>>>>>>
>>> which
>>>
>>>
>>>> is
>>>>
>>>>
>>>>>> actually LESS that you are seeing - the 2* discrepancy is odd,
>>>>>>
>>>>>>
>> but
>>
>>
>>>> the
>>>>
>>>>
>>>>>> low
>>>>>> power is in the area of what you measured..
>>>>>>
>>>>>> Andy G4JNT
>>>>>>
>>>>>>
>>>>>>
>>>>>> On 28 May 2017 at 19:34, [email protected]<marcocadeddu@tin.
>>>>>>
>>>>>>
>> it>
>>
>>
>>>>>> wrote:
>>>>>>
>>>>>>
>>>>>>
>>>>>>> Hi Chris,
>>>>>>>
>>>>>>> I tried to post this message on the reflector but apparently I
>>>>>>>
>>>>>>>
>>> had
>>>
>>>
>>>> no
>>>>
>>>>
>>>>>>> success..
>>>>>>> As promised I keep you updated but as you can read in the
>>>>>>> attachment the first trials were not enocouraging...
>>>>>>> Andy, may I ask you to read my report? your interpretation and
>>>>>>> suggestion are welcome!
>>>>>>>
>>>>>>> 73, Marco IK1HSS
>>>>>>>
>>>>>>>
>>>>>>> -----Original message-----
>>>>>>>
>>>>>>> From: "[email protected]" [email protected]
>>>>>>> Date: Sun, 28 May 2017 17:01:33 +0200
>>>>>>> To: [email protected]
>>>>>>> Subject: For today the FETs survived...
>>>>>>>
>>>>>>> Hi LF,
>>>>>>>
>>>>>>> hope that also the toroids of Chris survived!
>>>>>>> My FETs survived, but they are not working as expected :-(
>>>>>>> Attached the report on my attempt to duplicate the half bridge
>>>>>>>
>>>>>>>
>>> of
>>>
>>>
>>>>>>> Andy..
>>>>>>> Has anyone suggestions before I try to cook all connecting to
>>>>>>>
>>>>>>>
>>> the
>>>
>>>
>>>>>>> 180Vdc supply?
>>>>>>>
>>>>>>> Thank you
>>>>>>> 73 Marco IK1HSS
>>>>>>>
>>>>>>>
>>>>>>> --
>>>>>>> This message has been scanned by E.F.A. Project and is
>>>>>>>
>>>>>>>
>> believed
>>
>>
>>> to
>>>
>>>
>>>> be
>>>>
>>>>
>>>>>>> clean.
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> ---------- Forwarded message ----------
>>>>>>> From: "[email protected]"<[email protected]>
>>>>>>> To:<[email protected]>
>>>>>>> Cc:
>>>>>>> Bcc:
>>>>>>> Date: Sun, 28 May 2017 17:01:33 +0200 (CEST)
>>>>>>> Subject: For today the FETs survived...
>>>>>>> Hi LF,
>>>>>>>
>>>>>>> hope that also the toroids of Chris survived!
>>>>>>> My FETs survived, but they are not working as expected :-(
>>>>>>> Attached the report on my attempt to duplicate the half bridge
>>>>>>>
>>>>>>>
>>> of
>>>
>>>
>>>>>>> Andy..
>>>>>>> Has anyone suggestions before I try to cook all connecting to
>>>>>>>
>>>>>>>
>>> the
>>>
>>>
>>>>>>> 180Vdc supply?
>>>>>>>
>>>>>>> Thank you
>>>>>>> 73 Marco IK1HSS
>>>>>>>
>>>>>>>
>>>>>>> --
>>>>>>> This message has been scanned by E.F.A. Project and is
>>>>>>>
>>>>>>>
>> believed
>>
>>
>>> to
>>>
>>>
>>>> be
>>>>
>>>>
>>>>>>> clean.
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>
>>>>>
>>>>
>>>>
>>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>
>
>
|
