[hpsdr] Re Munin low output on 6m

Wed Dec 4 00:01:11 PST 2013

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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