hello
john wrote about improving the stability of the SX100 by soldering wires
beteen the tuning cap and the shield
are there more solutions to solve the problem ?
anyway I like the sx100 better than my SX 28A because the S X 28 drifts very
much . The sensitivity of the SX100 above 15 mc is also much better and with
the calibration it is more easy to find out where you are
I seldom use my SX 42 don 't like the tuning ,but great audio
hope someone has more advices for the SX100
hans

Thermal stability of the SX-28A can be improved. So, if you like it, except
for that problem, get an old Handbook out and read the section on
temperature compensation. A frequency counter, hair dryer with nozzle to
direct the heat, a calculator and a handful of temperature compensating caps
can become a pleasant evening project.

The mechanical stability issue of the SX-100 involves mechanical analysis of
the mechanical assemblies of that receiver. There is no simple mechanical
change that will fix the problem perfectly, rather the scientific approach
would be incremental. Stiffening up one assembly may simply transfer the
torque somewhere else. The simplest approach may be to isolate the entire
receiver from outside influence. If no outside stress is allowed to
influence the radio, then the inherent weakness of the chassis is
irrelevant.

An old friend complained that if he picked up the SX-100 and dropped it 2",
it would do a major jump in frequency, whereas other receivers would not.
The cure is to not pick up and drop the SX-100. It is not the ideal mobile
receiver, nor one to be used for narrow band cw during an earthquake.

73, Colin K7FM

Hallicrafters had some very competent engineers, and they solved the
mechanical problem of the SX-100. Their solution was the SX-101. It is
clear that they needed to add both depth and weight to solve the problem.

Consider the SX-100 as the Narrows Bridge (Galloping Gertie). The SX-101
was the replacement.

73, Colin K7FM

On Feb 9, 11:06 am, "COLIN LAMB" wrote:
Hallicrafters had some very competent engineers, and they solved the
mechanical problem of the SX-100. Their solution was the SX-101. It is
clear that they needed to add both depth and weight to solve the problem.

Consider the SX-100 as the Narrows Bridge (Galloping Gertie). The SX-101
was the replacement.

73, Colin K7FM

I have considered replacing the steel cables with regular dial cord. I
have not got around to it yet but I think the idea has merit. One can
only describe the mechanical instability/microphonics as "Guitar
String" like. Otherwise the tuning capacitor layout is similar to
other receivers of the era.

Tony

On Mar 14, 1:25*pm, WA6LZH wrote:
On Feb 9, 11:06 am, "COLIN LAMB" wrote:

Hallicrafters had some very competent engineers, and they solved the
mechanical problem of the SX-100. *Their solution was the SX-101. *It is
clear that they needed to add both depth and weight to solve the problem..

Consider the SX-100 as the Narrows Bridge (Galloping Gertie). *The SX-101
was the replacement.

73, *Colin *K7FM

I have considered replacing the steel cables with regular dial cord. I
have not got around to it yet but I think the idea has merit. One can
only describe the mechanical instability/microphonics as "Guitar
String" like. Otherwise the tuning capacitor layout is similar to
other receivers of the era.

Tony

I have my SX 100 mounted in a bookshelf and mounted a 117v muffin fan
to the bottom of the shelf above blowing air across the top to keep
the temp fairly stabile after warmup. It has cut down the drift. I
also found that by not setting the speaker directly on top of the rcvr
it cut the microphonic tendency. This also was also true of several
other Halli's. These solutions worked for me and I did not have to mod
the units in any way. I think I would keep the steel cables because
they will last forever over dial cord unless you really trace down
noise to them. 73 Mike KF6KXG