Are tube rigs more prone to giving RFI than newer solid state rigs?

An example, an older Heathkit SB 101 vs an Icom 735, both at 50 watts,
same antenna and ground, which one would be most likely to create more
problems with phone, TV etc ??

Gil

There are different issues with phone and television.

With regard to telephones, harmonic output of the transmitter makes little
difference. The phone is acting as an untuned crystal set. It is simply
defective design based upon mass production. It does not make any
difference what type of transmitter is being used, nor what frequency it is
on (generally). Interference is caused because the telephone has no
rejection. Interference can be reduced by moving the transmitting antenna
away from the telephone and telephone lines and/or by preventing the rf from
getting into the telephone. Interference filters are sold for telephones
that work in most (but not all) cases. Also, ferrite clamp ons may help.

The television is a bit different. Most likely, the same problem as
outlined above applies to televisions, also. But, if the affected
television uses an antenna (rather than cable or satellite), then harmonics
could be involved. Since older tube rigs were not required to meet as tight
of harmonic specs as the newer solid state rigs, it is possible that older
tube rigs might be more likely to cause interference to television sets.

In most cases, it is the television that is the problem, rather than the
transmitter. A more modern tube transmitter would be about the same as a
solid state transmitter in terms of liklihood to interfere.

Colin K7FM

gil wrote:
Are tube rigs more prone to giving RFI than newer solid state rigs?

An example, an older Heathkit SB 101 vs an Icom 735, both at 50 watts,
same antenna and ground, which one would be most likely to create more
problems with phone, TV etc ??

Gil


If the phone gets bothered, it is broken. If your CD player/record
player/cassette deck/stereo get bothered, they are also broken. Your VCR
was born broken, as its tape stores frequencies from DC thru the 80m.
Any of the above devices will be affected equally by either rig.

As to interferrence with devices that are intended to be receivers,
the Icom will likely be the worse offender. First, it is broadband
in its drivers and finals, so it will be producing lowel levels of
white noise over a significant bandwidth. Second, it is synthesized,
so it will be making a fair bit of phase noise. And third, it is
digital, so there will be some switching noise too. I find that it is
miserable to work on the same band with a modern SS transceiver in
the very near vicinity (same shack, next door, Field Day..). But the
new ones are much better than they once were.

The tube rig has very sharp tank circuits that resonate each stage
on the frequency being transmitted. It has a PI type loading network
that helps with antenna matching, and acts as an additional filter.
The tube rig will likely emit harmonics of the desired frequency, so
you can expect some interferrence that way. And the tube rig will
have some interesting frequencies that result from the internal
mixing schemes that will produce some hot spots.

All-in-all, it doesn't much matter. Big RF will crunch most
consumer electronics, thanks to the FCC sell out that allowed the
manufacturers to leave the RF filtering off, and only add it back
if the owner can figure out who to ask for it.

-Chuck

Some of the older tube transmitters were more prone to
TVI, since the manufacturers didn't bother with TVI
filters since there were not many televisions around to
bother! By the time you get to the gear made in the
60s (SB series, DX-60, etc.) the transmitters usually
included a multisection 30 MHz lowpass filter on the
output. Transmitter shielding is also important.

Pete

"Transmitter shielding "....you mean the case being properly grounded
right?

Couple of nights ago I was working CW on my old HW-101 @ 50 watts and
not only did my wife hear it over the phone but the person she was
speaking to as well! We dont have this problem over the wireless.

Thanks all for the input

Gil


Some of the older tube transmitters were more prone to
TVI, since the manufacturers didn't bother with TVI
filters since there were not many televisions around to
bother! By the time you get to the gear made in the
60s (SB series, DX-60, etc.) the transmitters usually
included a multisection 30 MHz lowpass filter on the
output. Transmitter shielding is also important.


Pete

gil wrote:
"Transmitter shielding "....you mean the case being properly grounded
right?

Couple of nights ago I was working CW on my old HW-101 @ 50 watts and
not only did my wife hear it over the phone but the person she was
speaking to as well! We dont have this problem over the wireless.

Thanks all for the input

You need to get intouch with the company that made the phone, and
tell them you need the RF interference kit. Call the 1-800 number
that is printed on the phone, and they will send it to you for free.
If they don't, then call the FCC and complain about the phone
manufacturer.

-Chuck

From: "gil"
Subject: Question on RFI and tube vs newer rigs
Date: Wednesday, November 23, 2005 8:07 PM

"Transmitter shielding "....you mean the case being properly grounded
right?

Couple of nights ago I was working CW on my old HW-101 @ 50 watts and
not only did my wife hear it over the phone but the person she was
speaking to as well! We dont have this problem over the wireless.

Thanks all for the input

Gil



Gil

More than that, the meters were often screened, and the AC line
cords had RF filters as well. This was mostly to reduce harmonic
radiation from the cabinet, which could be carried "common mode"
on the outside of the coaxial shield, or on the power cord.

Phone interference is overload related, and has nothing to do
with the quality of the transmitted signal. The phone is overly
sensitive to strong RF fields, regardless of their spectral
purity. As Chuck noted: some simple filters on the phone line
should help the problem.

Pete

This is not just about the phone, I guess I used the phone as one
example, but I was most concerned whether
an all tube rig would create more RFI problems overall than a solid
state rig.

Thanks......Gil


More than that, the meters were often screened, and the AC line
cords had RF filters as well. This was mostly to reduce harmonic
radiation from the cabinet, which could be carried "common mode"
on the outside of the coaxial shield, or on the power cord.


Phone interference is overload related, and has nothing to do
with the quality of the transmitted signal. The phone is overly
sensitive to strong RF fields, regardless of their spectral
purity. As Chuck noted: some simple filters on the phone line
should help the problem.


Pete

gil wrote:

This is not just about the phone, I guess I used the phone as one
example, but I was most concerned whether
an all tube rig would create more RFI problems overall than a solid
state rig.

Thanks......Gil

You seem to have a classic example of the RFI issue but I don't think
you can attribute it specifically to tube or solid-state technology
inasmuch as you can attribute it to the tighter rf packaging of more
modern rigs. Nothing about tubes per se makes them more prone to problems.

That said, while RF shielding integrity of a commercial xmtr/xcvr has
generally improved over the years, the RF integrity of consumer devices,
and that includes telephones, has gone down the tubes (no pun intended)
since Nixon went to China!

A poorly shielded xmtr in the ring with a cheap offshore home electronic
device is a guaranteed KO for both of them.

-Bill

Forget about the split-clamp ferrites. Opt for the donut style torroid with
a hole big enough to feed the fone line and connector and wrap at least 4
turns. This kept my 56k modem from hanging up when I was on 80 meters.

RF interactions are a fact of life and you need to know how to deal with it.
Most are easily overcome, except for the irate person who would rather be
irate than face it.

ac6tk

http://tekstuff.freespaces.com

"Chuck Harris" wrote in message
...
gil wrote:
Are tube rigs more prone to giving RFI than newer solid state rigs?

An example, an older Heathkit SB 101 vs an Icom 735, both at 50 watts,
same antenna and ground, which one would be most likely to create more
problems with phone, TV etc ??

Gil


If the phone gets bothered, it is broken. If your CD player/record
player/cassette deck/stereo get bothered, they are also broken. Your VCR
was born broken, as its tape stores frequencies from DC thru the 80m.
Any of the above devices will be affected equally by either rig.

As to interferrence with devices that are intended to be receivers,
the Icom will likely be the worse offender. First, it is broadband
in its drivers and finals, so it will be producing lowel levels of
white noise over a significant bandwidth. Second, it is synthesized,
so it will be making a fair bit of phase noise. And third, it is
digital, so there will be some switching noise too. I find that it is
miserable to work on the same band with a modern SS transceiver in
the very near vicinity (same shack, next door, Field Day..). But the
new ones are much better than they once were.

The tube rig has very sharp tank circuits that resonate each stage
on the frequency being transmitted. It has a PI type loading network
that helps with antenna matching, and acts as an additional filter.
The tube rig will likely emit harmonics of the desired frequency, so
you can expect some interferrence that way. And the tube rig will
have some interesting frequencies that result from the internal
mixing schemes that will produce some hot spots.

All-in-all, it doesn't much matter. Big RF will crunch most
consumer electronics, thanks to the FCC sell out that allowed the
manufacturers to leave the RF filtering off, and only add it back
if the owner can figure out who to ask for it.

-Chuck