[HBR] HBR-11 IF xformer critcal coupling?

[bignick at execpc.com]

Darrell,

Copious thanks for all the
helpful information!

I will forge ahead.  (I may just take
care to make tentative solder connections to the
I.F. transformers,
should I decide to later remove and further alter them.)

And,
thanks for the tip on the 80-meter coil!

By the way, there was
an April '64 QST article in which Crosby suggests replacing
the
existing HBR-11 oscillator triode section with an additional 6BH6 tube.

I think I may have just enough room to squeeze in another
tube (vertically).

Would you know if this is a worthwhile
addition?

Thanks again & 73

--Tom Nickel
KC9KEP 

> I wouldn't sweat it at this time.
After you get the I.F. wired, put a 100 
> KC signal into it and
make sure you get a good peak on each transformer 
> and 
> then continue on with the receiver construction. 
> 
> When you finish the receiver, two things should be apparent. First,
on 80 
> and 40 meters, you should have way too much receiver
gain. You should find 
> it necessary to back off on the manual
gain controls. This is normal. 
> Second, the I.F. should begin to
regenerate when you approach maximum with 
> the manual gain
control. If these objective are obtained, you're probably 
> okay.
If not, then I'd start slowly decreasing the distance between the 
> coils until this condition is obtained. 
> 
> BTW,
when you wind the 80 meter antenna coil, I'd only put 7/8 of a turn 
> on 
> the primary winding. I know this sounds ridiculous,
but even with the 
> coupling this light, you'll still have
excessive gain. 
> 
> 73, 
> Darrell, WA5VGO 
> 
> 
> 
> At 06:04 PM 3/22/2009 -0500,
bignick at execpc.com wrote: 
> 
> 
>>Hello all,

>> 
>>A question, please .. 
>> 
>>I have been following the instructions for modifying the K-Tran

>>262 kHz I.F. transformers 
>>as per the re-work
instructions at: 
>> http://www.qsl.net/k5bcq/HK/HK.html#SUB

>> 
>>I have modified the first coil by sliding
both coils to the ends 
>>of the coil form. 
>>It is
actually a small distance, perhaps 3/16" 
>>or so for each
coil. 
>> 
>>I note that when I route a signal thru
the 
>>modified I.F. coil that there is considerable signal 
>>loss as 
>>compared to an unmodified I.F.
transformer. 
>> 
>>On my remaining two 
>>coils, I have slid only one of the two I.F. coils to the end of
their 
>>coil forms and much more signal level is maintained.

>> 
>>My 
>>question is: How can I tell
(or can I tell) when I've got the coils 
>>under/over/critically 
>>coupled? 
>> 
>>Will I need to wire enough 
>>of the I.F. circuitry
in order to route a signal through the 
>>transformers when
they are correctly loaded? 
>> 
>>Thanks! 
>> 
>>--Tom Nickel AKA KC9KEP 
> 
> 
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