Martin Belcher had drunk about six pints when he lost his temper and banged on the neighbour's door at the block of flats in Pontefract.
Leeds Crown Court heard that the 59-year-old had "significant problems" with the neighbour over the past two years.
Prosecuting, Daniel Ingham said that the 59-year-old went to the flat to complain about the noise at around 7pm on September 11, and took the kitchen knife with him.
When the man answered the door, he threatened the man before pulling out the knife.
The neighbour told him to come back when he was sober and closed the door on him.
A former serviceman and HGV driver, the court was told that he was not a well man, suffered from PTSD and has Chron's disease.
He has had three operations on his bowel, and suffered two strokes. He takes 47 medication tablets a day.
Belcher, of Camelot Court, Viking Road, Pontefract, was later arrested and co-operated with police.
He admitted a charge of having a bladed article and using threatening, abusive or insulting words or behaviour.
Mitigating Emily Jenkins said: "He has been frank with the probation service and the police. He told them 'Everything is true. I'm not here to waste your time. I'm being pushed too far'."
She said that Belcher said he had been kept up all night by the noise and went to tell his neighbour the next evening to be quiet, taking the knife.
She said: "He accepts there's no justification for it."
Wakefield Council was aware of the problems between the pair, but Belcher said he would struggle to move because his elderly mother lives next door and he assists her.
The judge, Recorder Anesh Pema said: "You went armed with a kitchen knife, you made threats to kill him and pulled out the knife to emphasise those threats.
"He was not particularly upset or concerned and told you to come back when you were no longer drunk, and closed the door on you.
"He must have taken it seriously enough, because he called the police.
"You took the law into your own hands.
"It was wholly unacceptable, the knife makes it much more serious."
He gave him four months' jail, but suspended it for 12 months.
He was also given a one-month electronic tag curfew order, meaning he must remain at home between 8pm and 6am each day.