[hpsdr] Re Munin low output on 6m

[Kjell Karlsen]

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
>>>>>
>>>>> _______________________________________________
>>>>> HPSDR Discussion List
>>>>> To post msg: hpsdr at openhpsdr.org
>>>>> Subscription help:  
>>>>> http://lists.openhpsdr.org/listinfo.cgi/hpsdr-openhpsdr.org
>>>>> HPSDR web page: http://openhpsdr.org
>>>>> Archives: http://lists.openhpsdr.org/pipermail/hpsdr-openhpsdr.org/
>>>>>
>>>>>
>>>>
>>>>
>>>
>>>
>>
>>
>
>


-- 
Sendt med Operas e-postklient: http://www.opera.com/mail/

 1385718766.0