[Heathkit] Re: SB 102 vs HW 101

[Bwana Bob]

Yes, most of the circuits are identical, except for the VFO. In fact, some
of the minor features of the SB-101 can be easily added to the HW-100/101.
The SB-101 LMO was better, although if built right the HW-101 VFO is pretty
stable and the calibration can be interpolated to within 1-2 kHz. The HW-100
used the plastic spline gear "Harmonic Drive", which tended to have some
backlash. The HW-101 used 2 6:1 Jackson planetary ball drives in series.
This worked better, but if misaligned, one or both drives would wear out.

The SB-101/102 had provision for crystal control or an external LMO, making
MARS operation slightly outside the ham bands possible. That's academic
nowadays. I read that MARS is going to the 20 ppm frequency stability
standard and I don't know if any amateur radio can meet this. However, I
read of someone who uses an HW-101 on PSK-31, so it's stable enough for
that, after warm-up, of course.


						73,

						Bob WB2VUF


-----Original Message-----
From: heathkit-bounces at mailman.qth.net
[mailto:heathkit-bounces at mailman.qth.net] On Behalf Of kiyoinc at attglobal.net
Sent: Friday, August 04, 2006 5:58 AM
To: heathkit at mailman.qth.net
Subject: [Heathkit] Re: SB 102 vs HW 101

Ken Gordon W7EKB wrote:


> The HW-101 is a stripped down version of the SB-101. In point of fact, 
> ALL of the circuit boards in either rig are essentially identical.
...
> 
> The solid-state LMO is not as good as the tube-type one, although I 
> have heard that one can substitute a tube-type for the SS one easily 
> enough.
...
> 
> The only things I would change in either rig are 1) the CW sidetone and 
> thus the transmitter offset are 1Khz which is much too high for me, and 
> 2) I wish there were an easy way to change heterodyne oscillator 
> crystals for MARS use.  Although #2 can be done using an external 
> heterodyne oscillator, as I did for AFMARS phone patching, it could 
> have been a LOT easier if Heathkit had made some provision for it like 
> the KWM-2A did.

I didn't realize that the HW and the SB were so similar.  In my opinion, 
the VFO vs LMO isn't much of an issue these days.  Way back in the 
1960's the VFO dial was a primary frequency indicator,

"I make it, we're on 14,210."

"I've got 14,212 and I just set my LMO."

Other than frequency discussions, we sort-a just got in the ballpark and 
rocked the knob until we heard something familiar.  My SX-101A had a 
calibration mark every 5 kHz so I never knew where I was, other than, 
somewhere between 14,210 and 14,215, maybe.

Today, if the topic comes up, I'd flip on a digital radio, take a quick 
reading, and, oh yeah, we're on 14,212.3.

Since ham radio isn't channelized, and any radio built in the last 20 
years has 100 Hz readout or better (not that it means much on a 2,000 Hz 
wide SSB signal), if anyone really cared,  close enough is good enough 
on SSB and AM.

As for the oscillator crystal changes, maybe that's an application for 
Glen's Collins Crystal board.   I'm still thinking about getting one.

Too bad the SB-303/313 didn't have a flip top cabinet.

de ah6gi/4

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