Hallicrafters SX-71
 

I received a Hallicrafters SX-71 receiver from a SK estate. It is intact
and I bought a manual for it. It appears that the former owner was in the
process of working on of the IF transformers, so I will have to figure out
what was going on there. I haven't seen much conversation on this model on
the reflector, so I would like to know everyone's opinions who know anything
about it.

"I haven't seen much conversation on this model on the reflector, so I
would like to know everyone's opinions who know anything about it."

I just recapped and aligned one, and I find it to have excellent
fidelity on AM, and also very useable for SSB using the BFO, although
you have to manually reset it for the upper or lower SB. With the two
tuning dials (main and bandspread), it is not as easy to be precise
for finding an "exact" frequency, but it is just fine for roaming the
waves. Being general coverage it is also a good SWL receiver, which is
surely what it was marketed for. I think this was Hallicrafters first
double conversion unit. The crystal filter is useful to reduce QRM,
but adds some sonic "hollow sounding" effects. I like this unit.

Dan

It was actually marketed as a communications receiver with a target to the
amateur market. It was new in the early fifties. I bought one used in 1965
for something like $50.00. Had it for years and used it as part of my first
station. I let it go to a rehabilitaion hospital that wanted it for use by
patients who were to be lifelong residents of the institution. I found
another one just a few years back but had to pay $75.00 this time. It is a
good receiver for its age. Most equipment of this era usually will work
better with a systematic replacemant of the old paper/wax capacitors with
moder equivalents. If the object is to keep it authetic, you can even put
modern capacitors in the original cardboard tubes. There are a couple sites
showing how to do this with very respectable results.

I also ran into an article on how to soup up the receiver by changing the
cathode bias and the screen resistor of the second IF so that it would be
the same as the first and third IF. I haven't tried it yet, but I will one
of these days. The author of the article, Phil Atchley, KO6BB claims that
AGC action, especially on the higher bands is improved.

Hope this is of value to somebody.

73,

Wayne Irwin, W1KI/4
Ocala, Florida

"geojunkie" wrote in message
om...
"I haven't seen much conversation on this model on the reflector, so I
would like to know everyone's opinions who know anything about it."

I just recapped and aligned one, and I find it to have excellent
fidelity on AM, and also very useable for SSB using the BFO, although
you have to manually reset it for the upper or lower SB. With the two
tuning dials (main and bandspread), it is not as easy to be precise
for finding an "exact" frequency, but it is just fine for roaming the
waves. Being general coverage it is also a good SWL receiver, which is
surely what it was marketed for. I think this was Hallicrafters first
double conversion unit. The crystal filter is useful to reduce QRM,
but adds some sonic "hollow sounding" effects. I like this unit.

Dan

Wayne and Louise wrote:

It was actually marketed as a communications receiver with a target to the
amateur market. It was new in the early fifties. I bought one used in 1965
for something like $50.00. Had it for years and used it as part of my first
station. I let it go to a rehabilitaion hospital that wanted it for use by
patients who were to be lifelong residents of the institution. I found
another one just a few years back but had to pay $75.00 this time. It is a
good receiver for its age. Most equipment of this era usually will work
better with a systematic replacemant of the old paper/wax capacitors with
moder equivalents. If the object is to keep it authetic, you can even put
modern capacitors in the original cardboard tubes. There are a couple sites
showing how to do this with very respectable results.

I also ran into an article on how to soup up the receiver by changing the
cathode bias and the screen resistor of the second IF so that it would be
the same as the first and third IF. I haven't tried it yet, but I will one
of these days. The author of the article, Phil Atchley, KO6BB claims that
AGC action, especially on the higher bands is improved.

Hope this is of value to somebody.

73,

Wayne Irwin, W1KI/4
Ocala, Florida

Hello, Wayne. I live a few miles away, near Belleview. I'm about a
mile from 441 and the Belleview Santos elementary school. I worked at
microdyne till they started to close it down in 2001. I collect and
restore old ham receivers, test equipment and other oddball electronics
and books. I am working on a National NC-183R, and a TS-382 signal
generator right now.


--
We now return you to our normally scheduled programming.

Michael A. Terrell
Central Florida

" I also ran into an article on how to soup up the receiver by
changing the
cathode bias and the screen resistor of the second IF so that it would be
the same as the first and third IF. I haven't tried it yet, but I will one
of these days. The author of the article, Phil Atchley, KO6BB claims that
AGC action, especially on the higher bands is improved."

I also ran into this article, but on my receiver, which is a later
model, I could not see clearly what he meant. Perhaps the design
changed in the later versions, because it seems to have plenty of gain
to me. If you happen to figure this out let us know.

Dan