[hpsdr] Re Munin low output on 6m

Wed Dec 4 00:13:27 PST 2013

Hi all.

Just a comment: Both types can be used and I prefer ceramic types. But it  
must be either NP0 or C0G material with at least 500V rating. And 4 or 5  
with small values are better than 2 with higher values.

73, Kjell

På Wed, 04 Dec 2013 09:01:11 +0100, skrev Georg Prinz <getpri at t-online.de>:

> Hi Giovanni,
>
> the multilayer is a smt and the others are traditional ones.
> The smt I put on the original place of C26 and the others
> were soldered directly to the front of L4.
> 73, Georg, dl2kp
>
>
>
> Am Mittwoch, den 04.12.2013, 06:28 +0000 schrieb Giovanni Santin:
>> Hi Georg, about the capacitors you used, are they smt or the  
>> traditional ones with two wires sticking out ?
>>
>> Thanks, Giovanni, IZ0SQZ
>> -----Original Message-----
>> From: Georg Prinz <getpri at t-online.de>
>> Sender: hpsdr-bounces at lists.openhpsdr.orgDate: Mon, 02 Dec 2013 11:51:53
>> To: Kjell Karlsen<la2ni at online.no>
>> Reply-To: getpri at t-online.de
>> Cc: <hpsdr at lists.openhpsdr.org>; a.groff<k0vm at mchsi.com>;  
>> <K0VM at arrl.net>
>> Subject: Re: [hpsdr] Re Munin low output on 6m
>>
>> ***** High Performance Software Defined Radio Discussion List *****
>>
>> Hi Al,
>>
>> for caps C25 C26 C27 I am using
>> - one 479pf 5% 1kV AVX Multilayer ceramic capacitor
>> - one mica (glimmer) 200pF 5% and
>> - one mica 100 pF 5%
>>
>> With these components the output is about 120W - 130W on all bands.
>>
>> For L4 I tried various constructions.I expected that the version with a
>> coax-screen as primary coil and teflon cable as secondary coil will be
>> the best, because of less stray magnetic field. But the best is the one
>> with 25 Ohm coax cable.
>>
>> 73, Georg, dl2kp
>>
>>
>>
>>
>> Am Freitag, den 29.11.2013, 10:52 +0100 schrieb Kjell Karlsen:
>> > ***** High Performance Software Defined Radio Discussion List *****
>> >
>> > Hi Al.
>> >
>> > Back from holiday in Spain and today I tried to measure the output
>> > transformer using practically the same wire as you. With the 4 220 pF
>> > capacitors in place I find the compensation too high for 50 MHz so  
>> your
>> > findings are very strange. I get the best compensation using 660 pF.  
>> If
>> > this is correct in "real life" has to be checked with a complete  
>> Munin.
>> >
>> > Are you sure the capacitors are 220 pF? Can you measure the value of  
>> the
>> > capacitors?
>> >
>> > I have to do a test to find the exact value of the compensation.
>> > Unfortunately I do not have a complete unit so I have to build one.  
>> I´ll
>> > come back as soon as possible.
>> >
>> > 73, Kjell
>> >
>> >
>> >
>> >
>> >
>> >
>> >
>> > På Fri, 22 Nov 2013 20:40:48 +0100, skrev Kjell Karlsen  
>> <la2ni at online.no>:
>> >
>> > > ***** High Performance Software Defined Radio Discussion List *****
>> > >
>> > > Hi Al.
>> > >
>> > > It seems as if the compensation of the output transformer might be
>> > > different with the type of wire you have used compared with what I  
>> used.
>> > > You may try to remove one of the capacitors and try again to see if  
>> it
>> > > is worse or better.
>> > >
>> > > Can you please measure the wire diameter and the outer diameter of  
>> the
>> > > insulation.
>> > >
>> > > I´ll test with the VNA when I come home next week. At the moment I  
>> am in
>> > > Spain for a short holiday.
>> > >
>> > > 73, Kjell
>> > >
>> > >
>> > >
>> > >
>> > >
>> > > På Fri, 22 Nov 2013 17:50:09 +0100, skrev a.groff <k0vm at mchsi.com>:
>> > >
>> > >> Kjell,
>> > >>     Replacing the Capacitors and I can now get 115 watt at 50mhz  
>> and a
>> > >> bit more at 53mhz.
>> > >>
>> > >>     However, at 28mhz I can only get 90 watts and less at  30mhz  
>> .. ( a
>> > >> lot less at 42 mhz ).
>> > >> It appears to start going into saturation at about 75 watt at  
>> 28mhz.
>> > >> ( I had 100+w at 28 before replacing the capacitors.)
>> > >>
>> > >>    I think I shall try tightening up the turns on L4  (??? ) if  
>> your
>> > >> think that would help.
>> > >>
>> > >> AL, K0VM
>> > >>
>> > >>
>> > >>
>> > >>
>> > >> On 11/16/2013 11:04 AM, a.groff wrote:
>> > >>> Kjell,
>> > >>>    I have the Caps on order and will report back..
>> > >>>    If the problem is in the final output transformer shouldn't the
>> > >>> t1-2 source current increase as driver is increased above  
>> saturation ??
>> > >>>    At 40watts output ( below saturation ) the drive required for  
>> 40
>> > >>> watts out is basically flat from 160m thru 6m.
>> > >>>
>> > >>> AL, K0VM
>> > >>>
>> > >>>
>> > >>> On 11/16/2013 3:30 AM, Kjell Karlsen wrote:
>> > >>>> Hi Al.
>> > >>>>
>> > >>>> I agree that the problem might be one of the capacitors. All my
>> > >>>> problems with low power on 6 meter has been with the output
>> > >>>> transformer and components around it.
>> > >>>>
>> > >>>> Please report back when you have tested with new capacitors.
>> > >>>>
>> > >>>> 73, Kjell
>> > >>>>
>> > >>>>
>> > >>>>
>> > >>>>
>> > >>>>
>> > >>>> På Sat, 16 Nov 2013 00:33:28 +0100, skrev Bob Campbell
>> > >>>> <joan-bob at bigpond.net.au>:
>> > >>>>
>> > >>>>> ***** High Performance Software Defined Radio Discussion List  
>> *****
>> > >>>>>
>> > >>>>> Hi Al,
>> > >>>>>
>> > >>>>> Check caps C25 C26 C27 are all ok.
>> > >>>>>
>> > >>>>> Mine failed when I went to load it up on 6m, blew the cermic cap
>> > >>>>> apart.
>> > >>>>>
>> > >>>>> As Kjell suggested in a previous post replace these caps with  
>> four
>> > >>>>> 220pf
>> > >>>>> 500vw 1206 caps.  Since doing this mine has been ok.  I suspect  
>> with
>> > >>>>> this mod the current is shared evenly between all 4 caps and the
>> > >>>>> circuit
>> > >>>>> is much more stable and I have no trouble getting the desired  
>> output
>> > >>>>> on
>> > >>>>> 6m now.
>> > >>>>>
>> > >>>>> 73's
>> > >>>>> Bob.c
>> > >>>>> Vk4xv
>> > >>>>>
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>> > >>>
>> > >>
>> > >>
>> > >
>> > >
>> >
>> >
>>
>>
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