[Collins] Thoughts on KWS-1 options

Mon Nov 25 11:41:04 EST 2013

Use of the on-line calculator for r.f. exposure at

http://hintlink.com/power_density.htm

will give the amount of r.f. to which someone is exposed.

Make sure and read the instructions where the average output power is concerned.  For SSB operation the average is 20% of the peak power, for CW operation the average is 40% of "key down" power, and for AM, PM, FM, and data, the average is 100% of "key down" power.

Also, the actual time of transmissions enter into the equation.  For an "average" QSO with just another station, since the time spent in actual transmission is about half, then the power has to be adjusted to 50% of what one gets from the mode calculations.

Especially on 160-meters, 80/75-meters, and 40-meters, running the full 1500-watts of the legal limit does not exceed the exposure limits within just a very few feet of the antenna.

Because FCC regulations do require amateur radio operators to calculate the exposure from their transmitters

http://www.fcc.gov/encyclopedia/radio-frequency-safety

http://www.rfcafe.com/references/electrical/fcc-maximum-permissible-exposure.htm

http://www.arrl.org/fcc-rf-exposure-regulations-the-station-evaluation

http://www.arrl.org/the-fcc-s-new-rf-exposure-regulations

http://www.rfsafetysolutions.com/RF%20Radiation%20Pages/FCC_Regulations.html

among other sites, I have taken the time to actually use the calculator to calculate the exposure limits for every band upon which I operate, for every emission that I use, for every different antenna that I have for each band, at the maximum power that I can run.  The calculator allows the results to be printed.  These "print outs" are then placed in a 3-ring binder.

Even though there is an extremely small chance that anyone, including the FCC, would ever want to see these print outs, the less than half-hour that it took to do the calculations is, in my mind, good insurance just in case a neighbor, or someone else, ever complained about possible r.f. exposure.

Glen, K9STH

Website:  http://k9sth.com

On Sunday, November 24, 2013 9:37 PM, Dr. Gerald N. Johnson <geraldj at netins.net> wrote:

On 11/24/2013 8:11 PM, Corey Sukalich wrote:
> Hi everyone,
>
> It has been a while since I have last posted (under a previous name
> but the same callsign) - I’m presently planning to purchase a KWS-1
> and would like some advice from those on-list regarding my options.
> The funds are in-place and I am interested in proceeding before the
> end of the year.
>
> My first option is a recently discovered unit (S/N 700) in town - no
> moving costs but selling around $1500 AS-IS without being powered on
> (price may be further negotiable - not sure yet - should it be?).
> The T/R relay and blower hose are missing.  Unit is overall a B/B-
> condition otherwise - some little nicks/dents and the power supply
> door won’t fully close completely but there may just be an issue with
> the latch or hinges.  Since the unit hasn’t been powered up there is
> some risk of bad transformers - but I don’t know how significant that
> risk might be.  The exciter has had all tubes checked and any low/bad
> ones replaced.  The PA loading and tuning knobs have a bit of drag
> and one looks slightly wobbly - but it could be due to the unit being
> in a garage in 20 degree weather.  No restoration has been performed
> as far as I am aware - there are service bulletins along with the
> manual that comes with the unit so it may have been modified from
> stock to keep up to date - the original (non- 4:1 tuning knob) is
> installed on the exciter.

There are probably other service bulletins in the collections available 
as well as in the article or two on care and maintenance of the KWS-1. 
PA cooling blower bearings is another place to need attention. A 
workable hose can probably be found as a replacement hose for a shop 
vac. A relay can be found though maybe not the original.

There is always risk of transformer failure made greater by storage in a 
damp location.
>
> My second option is a Howard Mills restoration at considerable
> expense ($4200 + shipping).
>
> My third option is to explore other units out there that are
> currently or might be for sale.  I presume the price will be somewhat
> in between the first two options.
>
> I would appreciate any opinions (including on the pricing of the
> various units as well as the work required for restoring a unit that
> is still factory original or mostly so) or offers from KWS-1 owners
> that may be looking to sell.  My 75A-4 receiver was a Howard Mills
> restoration which was not repainted and in what I would approximate
> as “A to A-” condition.  Ideally I would like to have a station where
> all pieces are approximately in the same condition.
>
> I look forward to any comments from those on-list - for what it is
> worth - I’ve done recapping jobs on older Hi-Fi amplifiers and the
> like.  If a KWS-1 restoration job isn’t much more advanced than that
> I could probably take on such a project with ease.  I’d also be
> curious to know if a few scuffs on the cabinet could be touched up or
> if a repaint would be in order.  Also I’m wondering how hard it is to
> find parts if they are needed.  Thanks for any sage advice that is
> offered - and with any luck I’ll be on the air with the Gold Dust
> Twins before too long!  (As a side-note I’d be appreciative of any
> commentary regarding attic antennas for those in covenant restricted
> locations - I know it should be possible to be on the air without
> making trouble by having outdoor antennas).

There are molded oiled paper capacitors, "black beauties," that need to 
be replaced without testing. While not original looking, orange drops 
work well and will for a very long time. Black beauties were leaky the 
day they were installed and the leakage has increased with age. 40 years 
ago they had unacceptable leakage. Can type electrolytics will be 
hardest to find but some have cut them open and installed modern 
components. Electrolytics age poorly when not used. Sometimes they can 
be reformed by bringing up the voltage slowly, but sometimes they fail 
violently after that filling the chassis with aluminum foil and crepe 
paper saturated with electrolyte. Its a real mess to clean up. Enough to 
cause me to demand a recent date code on new electrolytics.

Scuffs in wrinkle paint are especially hard to fix. There is little 
information on wrinkling paint these days and those with the formulae 
and the skills have become permanently quiet.

An attic antenna can get out, it will be close to the ground so its 80 
and 40 meter radiation will be basically straight up, good for the state 
your in and the surrounding states.

Check for RF exposure. With it that close to the living quarters and 
that much power, I suspect it won't pass FCC RF exposure regulations and 
that all electronic devices in the house will object to the transmitted 
RF. I have a dipole a few feet above the house roof ridge outside and on 
6m my automatic tuner objects when I run 100 watts. The interface 
between the tuner and the radio for radio control for automatic tuning 
at low power didn't survive, now if plugged in it keys the radio all the 
time. My Verizon wireless modem would require powering down and 
restarting after I made a contact on 6m also. It was on the end of a USB 
cable and probably less than 8 feet from the end of the dipole on the roof.

Perhaps its time to hide a vertical inside a flag pole and become super 
patriotic flying a flag every day if the home owner's group doesn't 
object to a flag pole.

73, Jerry, K0CQ, Technical Adviser to the Collins Radio Association.
>
> Regards&  73, Corey N9WIV
>

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