RG-62U Coax

[David Poplewski]

Ed you are right on target. As a former Heath employee from 1968 through
1992 (24yrs) at the Heathkit plant in St.Joseph Mi., I lived and breathed
Heathkit amateur radio from technician through product line manager. I've
read many a posting the last few days about Heath and have been reluctant to
respond because the subject of Heath and what happened to a great company
breaks my heart. I certainly have better information then well meaning
outsiders.

Now to the purpose of the RG-62 on the SB-301/401 combination. RG-62 cable
was selected for it impedance factor (93 ohms) and it's velocity factor
across the frequency spectrum of the HFO oscillators. The use of other than
RG-62 is not as critical for the LMO and BFO cables because the frequency
never gets above 5 MHz, but the HFO frequency changes from band to band. As
you would increase your operating band to say 10 meters the HFO frequency
made quite a leap from the 80 meter band to 10 meter band. In order to keep
the HFO injection voltage level as constant as possible over this range into
the mixer stage in the transmitter,(so the transmitter maintains a level
output) it was necessary to use a cable that presented the least amount of
attenuation over this frequency range.
Of course if you had the accessory crystal pack in the SB-401, these cables
were not even required. They were indeed critical for transceiver operation
without the crystal pack.

I hope this helps.

David Poplewski KC8IV
Former Heath 1968-1992
e-mail cleezhon-niles at att.net

> -----Original Message-----
> From: Heathkit Owners and Collectors List
> [mailto:HEATH at LISTSERV.TEMPE.GOV]On Behalf Of Ed Richards
> Sent: Thursday, November 01, 2001 1:35 AM
> To: HEATH at LISTSERV.TEMPE.GOV
> Subject: Re: RG-62U Coax
>
>
> I guess I am one of those "purists". I disagree and think someone should
> present the other side so this fellow doesn't get the wrong idea. I feel
> there are very valid reasons why the Heathkit engineers specify a
> specific cable for these applications. Unless you are an experienced
> engineer, I don't believe in substituting for any specified part. It may
> work sometimes or you may have undesirable side effects that you are not
> even aware of. My advice: stick with the specified part unless you think
> you are smarter than the engineers who designed it !
>
> If Larry will send me his mailing address, I will send him some RG-62
> gratis. I would rather do that, than see him use the wrong cable. Also,
> stick with the 2'. They specified that for a reason, too.
>
> Ed Richards
>
> On Wed, 31 Oct 2001 21:29:37 -0800 Glen Zook <gzook at YAHOO.COM> writes:
> > Although some "purists" will disagree, I have used
> > RG58/U on both my original SB-301 / SB-401 combination
> > (1967 to 1973) and on my present SB-301 / SB-401
> > combination with NO PROBLEMS what-so-ever.  Also used
> > it between a SB-303 and the SB-401 before I traded off
> > the SB-303.
> >
> > Just keep the lengths as short as possible for the
> > three cables that are used for the circuits that
> > control the transceive functions.  The antenna cable
> > can be any convenient length.
> >
> > Glen, K9STH
> >
> >
> > --- Larry Bratcher <lbratche at SWBELL.NET> wrote:
> >
> > Can I use some other coax besides RG-62
> >
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