Julian Macassey <julian%bongo.UUCP@nosc.mil> (04/30/91)
There has been much banter recently on the subject of
interference to phones by various radio transmitters. I sent some
documents about this to the original poster and let the slanging
continue.
Late last week I received my copy of "QST" the "American
Rifleman" mag of the Radio Amateur Association in the US (American
Radio Relay League). There on Page 22 of the May 1991 issue was an
article "Basic Steps Towards Eliminating Telephone RFI". This is not a
wonderful article. It has a few things wrong.
Let me just state a few things about telephone interference. I
have had some experience with telephone RFI. I used to work for some
phone manufacturers. We used to get customers calling in and whining
because their phones were terrible phones and lousy radio receivers.
Most reported cases of RFI are from Commercial AM (Medium
Wave) broadcast. There are a few reasons for this: 1. They are on most
of the time. 2. They use AM which can be understood when rectified
unlike FM/CW/SSB etc. 3. The Broadcast stations run higher power and
sites once safely in the boonies pushing 50Kw are now often smack in
the middle of Yuppie-ville. Nothing whines like an unhappy Yuppie -
They have the time, they have the money, they are the lawyers.
If you use real phones - Not gas station give-aways - you
should have few RFI problems. If you do persist in using a phone
sensitive to RFI, it can be fixed, it just requires more skill.
The phone police will not be happy if you open a phone and
insert a capacitor, this contravenes FCC Part 68 etc. But if you don't
tell people that you are breaking the law with a hot soldering iron,
they will only love you when the problem goes away.
Unfortunately, many people complain of interference when there
is none. These people will cause much grief as they are hard to
satisfy.
I have a collection of three documents which our esteemed
Moderator may wish to run in the digest. I can always e-mail them to
maidens (and masters) in distress. The docs are as follows:
(1) An ASCII copy of FCC Field Bulletin FO-10. Dated 1986. About 7K in
length.
(2) An ASCII copy of Bell System Practice (BSP) 500-150-100 " Radio
Signal Suppression for Telephone Sets". Dated 1974. About 10K in
length. This was the official "Ma Bell Party-line". Has good advice in
it.
(3) An ASCII copy of a February, 1988 article in {Popular
Communications Magazine}. This is written by myself and gives some
hints on handling the dreaded RFI problem. About 12K in length.
Julian Macassey, n6are julian@bongo.info.com ucla-an!denwa!bongo!julian
742 1/2 North Hayworth Avenue Hollywood CA 90046-7142 voice (213) 653-4495
[Moderator's Note: If you wish to send them along, they'll be put in
the archives where interested readers can obtain them. PAT]