[Hallicrafters] R-274 Band VI Update

[thoyer]

Correction, I found out that band VI operates on the second harmonic of the
VFO (missed the fine print in the manual until it was pointed out to me....)

Took some readings tonight:

Went back to the "as built" configuration and took some measurements at V3-1
the input of the VFO to the first mixer.

Using a Fluke Scopemeter set to read Vpp and freq. I took two readings on
each band - main tuning fully CW(high end of band) and main tuning fully CCW
(low end of band). Results:

Band 1 CCW = .983mhz, 30vpp
Band 1 CW = 1.744mhz, 62vpp

Band 2 CCW = 1.7mhz, 23.3vpp
Band 2 CW = 3.485mhz, 54vpp

Band 3 CCW = 3.4mhz, 20vpp
Band 3 CW = 7.5mhz 58vpp

Band 4 CCW = 12.82mhz, 8.5vpp
Band 4 CW = 19.86mhz, 18vpp

Band 5 CCW = 19.2mhz, 2.2vpp
Band 5 CW = 32mhz, 4.5vpp

Band 6 CCW = NADA
Band 6 CW = 27.34, 6.7vpp

Watching the scope while tuning through band 6 the oscillator stops working
around 20mhz on the scope, 36mhz on the dial which may or may not be
close...

I also noted that while tuning through the bands and monitoring the voltage
on V3 pin1, it increases and decrease several times on the higher bands. At
some points it gets so low that I wonder if any signal would be heard. 

I don't have much time tonight to "play" tonight so until tomorrow........

I'm open for suggestions....

Tom
W3TA
 

-----Original Message-----
From: hallicrafters-bounces at mailman.qth.net
[mailto:hallicrafters-bounces at mailman.qth.net] On Behalf Of thoyer
Sent: Tuesday, February 20, 2018 7:10 PM
To: 'Jacques Fortin'; hallicrafters at mailman.qth.net
Subject: Re: [Hallicrafters] R-274 Band VI Update

Hi Jacques, 

The coil only has about 6 turns on it wide spaced so no possibility of a
short there. I did look at the slug in the coil and it appears intact and
does "tune" the resonant freq with adjustment.

I re-read the theory of operation and it appears that band 6 functions just
like the other higher bands VFO signal plus 6mc.

I'm about to go work on it now - we'll see what happens tonight....

Tom

-----Original Message-----
From: hallicrafters-bounces at mailman.qth.net
[mailto:hallicrafters-bounces at mailman.qth.net] On Behalf Of Jacques Fortin
Sent: Tuesday, February 20, 2018 1:57 PM
To: 'Thomas Hoyer'; hallicrafters at mailman.qth.net
Subject: Re: [Hallicrafters] R-274 Band VI Update

Hi Tom,
You could have a short between coil turns or the ferrite slug within the
coil (if there is one, say) is the bad one.
Are you sure that this top band do not works "in reverse" , meaning having
the LO working BELOW the received frequency by the value of the first IF ??
Just ideas.... remembering that your set was beaten up before !

73, Jacques, VE2JFE

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