[AMRadio] Halli HT37 Phasing Mod problem


jeremy-ca km1h at jeremy.mv.com
Wed Nov 28 09:27:12 EST 2007


Ive owned many phasing rigs starting with a HB W2EWL, all the Central 
Electronics, and a pair of HT-37's.

While a single tone can be used to get a good indicated null it is only at 
that one frequency. It is better to use two tones. If that isnt possible 
then use a tape loop or digital recorder with a fairly flat speech 
recording. Something recorded off the BCB with good AVC works well. Then 
adjust and make sure the high frequencies are suppressed as well as the low.

Carl
KM1H



----- Original Message ----- 
From: <ne1s at neandertech.com>
To: "Discussion of AM Radio in the Amateur Service" 
<amradio at mailman.qth.net>
Sent: Wednesday, November 28, 2007 8:49 AM
Subject: RE: [AMRadio] Halli HT37 Phasing Mod problem


> ----- Original Message -----
> Subject: RE: [AMRadio] Halli HT37 Phasing Mod problem
> Date: Tue, November 27, 2007 21:16
> From: "Gary Schafer" <garyschafer at comcast.net>
>
>> The best way that I have found to align phasing rigs is to talk into the
>> mike while listening to the opposite side band and tune things for 
>> minimum
>> (best side band suppression). A nice long ooooooh works good. You will 
>> need
>> to switch side bands and do the same on the other as they interact. You 
>> can
>> tune it for really great suppression on one side band while the other one
>> won't be so great.
>> Find the point where the suppression is nearly equal on each side band
> while
>> listening to the opposite side.
>>
>
> Never owned an HT-37, but have played with various other phasing-type
> rigs, one of them home-grown (by me).
>
> Here's a few more ideas:
>
> Use your scope to trace a "Lissijous figure" - in this case a circle - to
> dial in the correct phase and amplitude relationship between the two
> quadrature audio channels. You'll wand to feed a sine wave into the audio
> input of the rig for this; a 1Kc tone should work OK. Make sure you don't
> overdrive the audio stages! Also, with the same setup, you can use a
> selective receiver (something with a bandpass of 500Kc/s or less) to sift
> out the lower sideband (1 KHz below the transmit (virtual) carrier
> frequency), carrier (which should be very weak, but probably audible)),
> and the upper sideband.(1 KHz above the carrier freq.). Tune in the
> sideband you want to suppress and null it out. Then tune in the opposite
> sideband, select the other sideband on the transmitter, and do the same.
> There will be a compromise between ultimate opposite sideband suppression
> and getting the best suppression possible for both USB and LSB operation.
>
> I've never used the Lissajous figure method myself, but it makes sense it
> should work. I've used the 2nd method several times.
>
> 73/GL,
> -Larry/NE1S
> ______________________________________________________________
> Our Main Website: http://www.amfone.net
> AMRadio mailing list
> List Rules (must read!): http://w5ami.net/amradiofaq.html
> List Home: http://mailman.qth.net/mailman/listinfo/amradio
> Help: http://mailman.qth.net/mmfaq.html
> Post: mailto:AMRadio at mailman.qth.net
> To unsubscribe, send an email to amradio-request at mailman.qth.net with
> the word unsubscribe in the message body.
> 



More information about the AMRadio mailing list

This page last updated 23 Oct 2017.